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GNU Info File | 1992-10-30 | 51KB | 900 lines

This is Info file ../info/emacs, produced by Makeinfo-1.49 from the input file emacs.texi. This file documents the GNU Emacs editor. Copyright (C) 1985, 1986, 1988, 1992 Richard M. Stallman. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled "The GNU Manifesto", "Distribution" and "GNU General Public License" are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the sections entitled "The GNU Manifesto", "Distribution" and "GNU General Public License" may be included in a translation approved by the author instead of in the original English. File: emacs, Node: Comments, Next: Macro Expansion, Prev: Matching, Up: Programs Manipulating Comments ===================== The comment commands insert, kill and align comments. `M-;' Insert or align comment (`indent-for-comment'). `C-x ;' Set comment column (`set-comment-column'). `C-u - C-x ;' Kill comment on current line (`kill-comment'). `M-LFD' Like RET followed by inserting and aligning a comment (`indent-new-comment-line'). The command that creates a comment is `Meta-;' (`indent-for-comment'). If there is no comment already on the line, a new comment is created, aligned at a specific column called the "comment column". The comment is created by inserting the string Emacs thinks comments should start with (the value of `comment-start'; see below). Point is left after that string. If the text of the line extends past the comment column, then the indentation is done to a suitable boundary (usually, at least one space is inserted). If the major mode has specified a string to terminate comments, that is inserted after point, to keep the syntax valid. `Meta-;' can also be used to align an existing comment. If a line already contains the string that starts comments, then `M-;' just moves point after it and re-indents it to the conventional place. Exception: comments starting in column 0 are not moved. Some major modes have special rules for indenting certain kinds of comments in certain contexts. For example, in Lisp code, comments which start with two semicolons are indented as if they were lines of code, instead of at the comment column. Comments which start with three semicolons are supposed to start at the left margin. Emacs understands these conventions by indenting a double-semicolon comment using TAB, and by not changing the indentation of a triple-semicolon comment at ;; This function is just an example ;;; Here either two or three semicolons are appropriate. (defun foo (x) ;;; And now, the first part of the function: ;; The following line adds one. (1+ x)) ; This line adds one. In C code, a comment preceded on its line by nothing but whitespace is indented like a line of code. Even when an existing comment is properly aligned, `M-;' is still useful for moving directly to the start of the comment. `C-u - C-x ;' (`kill-comment') kills the comment on the current line, if there is one. The indentation before the start of the comment is killed as well. If there does not appear to be a comment in the line, nothing is done. To reinsert the comment on another line, move to the end of that line, do `C-y', and then do `M-;' to realign it. Note that `C-u - C-x ;' is not a distinct key; it is `C-x ;' (`set-comment-column') with a negative argument. That command is programmed so that when it receives a negative argument it calls `kill-comment'. However, `kill-comment' is a valid command which you could bind directly to a key if you wanted to. Multiple Lines of Comments -------------------------- If you are typing a comment and find that you wish to continue it on another line, you can use the command `Meta-LFD' (`indent-new-comment-line'), which terminates the comment you are typing, creates a new blank line afterward, and begins a new comment indented under the old one. When Auto Fill mode is on, going past the fill column while typing a comment causes the comment to be continued in just this fashion. If point is not at the end of the line when `M-LFD' is typed, the text on the rest of the line becomes part of the new comment line. Options Controlling Comments ---------------------------- The comment column is stored in the variable `comment-column'. You can set it to a number explicitly. Alternatively, the command `C-x ;' (`set-comment-column') sets the comment column to the column point is at. `C-u C-x ;' sets the comment column to match the last comment before point in the buffer, and then does a `Meta-;' to align the current line's comment under the previous one. Note that `C-u - C-x ;' runs the function `kill-comment' as described above. `comment-column' is a per-buffer variable; altering the variable affects only the current buffer, but there is a default value which you can change as well. *Note Locals::. Many major modes initialize this variable for the current buffer. The comment commands recognize comments based on the regular expression that is the value of the variable `comment-start-skip'. This regexp should not match the null string. It may match more than the comment starting delimiter in the strictest sense of the word; for example, in C mode the value of the variable is `"/\\*+ *"', which matches extra stars and spaces after the `/*' itself. (Note that `\\' is needed in Lisp syntax to include a `\' in the string, which is needed to deny the first star its special meaning in regexp syntax. *Note Regexps::.) When a comment command makes a new comment, it inserts the value of `comment-start' to begin it. The value of `comment-end' is inserted after point, so that it will follow the text that you will insert into the comment. In C mode, `comment-start' has the value `"/* "' and `comment-end' has the value `" */"'. `comment-multi-line' controls how `M-LFD' (`indent-new-comment-line') behaves when used inside a comment. If `comment-multi-line' is `nil', as it normally is, then the comment on the starting line is terminated and a new comment is started on the new following line. If `comment-multi-line' is not `nil', then the new following line is set up as part of the same comment that was found on the starting line. This is done by not inserting a terminator on the old line, and not inserting a starter on the new line. In languages where multi-line comments work, the choice of value for this variable is a matter of taste. The variable `comment-indent-hook' should contain a function that will be called to compute the indentation for a newly inserted comment or for aligning an existing comment. It is set differently by various major modes. The function is called with no arguments, but with point at the beginning of the comment, or at the end of a line if a new comment is to be inserted. It should return the column in which the comment ought to start. For example, in Lisp mode, the indent hook function bases its decision on how many semicolons begin an existing comment, and on the code in the preceding lines. File: emacs, Node: Macro Expansion, Next: Balanced Editing, Prev: Comments, Up: Programs Viewing How C Macros Expand =========================== When you are debugging C code that uses macros, sometimes it is hard to figure out precisely how the macros expand. The command `M-x c-macro-expand'. It runs the C preprocessor and shows you what expansion results from the region. The portion of the buffer before the region is also included in preprocessing, for the sake of macros defined there, but the output from this part isn't shown. File: emacs, Node: Balanced Editing, Next: Lisp Completion, Prev: Macro Expansion, Up: Programs Editing Without Unbalanced Parentheses ====================================== `M-(' Put parentheses around next sexp(s) (`insert-parentheses'). `M-)' Move past next close parenthesis and re-indent (`move-over-close-and-reindent'). The two commands, `M-(' (`insert-parentheses') and `M-)' (`move-over-close-and-reindent'), are designed to facilitate a style of editing which keeps parentheses balanced at all times. `M-(' inserts a pair of parentheses, either together as in `()', or, if given an argument, around the next several sexps, and leaves point after the open parenthesis. Instead of typing `( F O O )', you can type `M-( F O O', which has the same effect except for leaving the cursor before the close parenthesis. Then you would type `M-)', which moves past the close parenthesis, deleting any indentation preceding it (in this example there is none), and indenting with LFD after it. File: emacs, Node: Lisp Completion, Next: Documentation, Prev: Balanced Editing, Up: Programs Completion for Lisp Symbols =========================== Usually completion happens in the minibuffer. But one kind of completion is available in all buffers: completion for Lisp symbol names. The command `M-TAB' (`lisp-complete-symbol') takes the partial Lisp symbol before point to be an abbreviation, and compares it against all nontrivial Lisp symbols currently known to Emacs. Any additional characters that they all have in common are inserted at point. Nontrivial symbols are those that have function definitions, values or properties. If there is an open-parenthesis immediately before the beginning of the partial symbol, only symbols with function definitions are considered as completions. If the partial name in the buffer has more than one possible completion and they have no additional characters in common, a list of all possible completions is displayed in another window. File: emacs, Node: Documentation, Next: Change Log, Prev: Lisp Completion, Up: Programs Documentation Commands ====================== As you edit Lisp code to be run in Emacs, the commands `C-h f' (`describe-function') and `C-h v' (`describe-variable') can be used to print documentation of functions and variables that you want to call. These commands use the minibuffer to read the name of a function or variable to document, and display the documentation in a window. For extra convenience, these commands provide default arguments based on the code in the neighborhood of point. `C-h f' sets the default to the function called in the innermost list containing point. `C-h v' uses the symbol name around or adjacent to point as its default. Documentation on Unix commands, system calls and libraries can be obtained with the `M-x manual-entry' command. This reads a topic as an argument, and displays the text on that topic from the Unix manual. `manual-entry' always searches all 8 sections of the manual, and concatenates all the entries that are found. For example, the topic `termcap' finds the description of the termcap library from section 3, followed by the description of the termcap data base from section 5. File: emacs, Node: Change Log, Next: Tags, Prev: Documentation, Up: Programs Change Logs =========== The Emacs command `M-x add-change-log-entry' helps you keep a record of when and why you have changed a program. It assumes that you have a file in which you write a chronological sequence of entries describing individual changes. The default is to store the change entries in a file called `ChangeLog' in the same directory as the file you are editing. The same `ChangeLog' file therefore records changes for all the files in the directory. A change log entry starts with a header line that contains your name and the current date. Aside from these header lines, every line in the change log starts with a tab. One entry can describe several changes; each change starts with a line starting with a tab and a star. `M-x add-change-log-entry' visits the change log file and creates a new entry unless the most recent entry is for today's date and your name. In either case, it adds a new line to start the description of another change just after the header line of the entry. When `M-x add-change-log-entry' is finished, all is prepared for you to edit in the description of what you changed and how. You must then save the change log file yourself. The change log file is always visited in Indented Text mode, which means that LFD and auto-filling indent each new line like the previous line. This is convenient for entering the contents of an entry, which must all be indented. *Note Text Mode::. An alternative convenient command for starting a change log entry is `C-x 4 a' (`add-change-log-entry-other-window'). It resembles `add-change-log-entry' except that it visits the change log in another window, and always uses the file `./ChangeLog'--it does not ask you for the file name. Here is an example of the formatting conventions used in the change log for Emacs: Wed Jun 26 19:29:32 1985 Richard M. Stallman (rms at mit-prep) * xdisp.c (try_window_id): If C-k is done at end of next-to-last line, this fn updates window_end_vpos and cannot leave window_end_pos nonnegative (it is zero, in fact). If display is preempted before lines are output, this is inconsistent. Fix by setting blank_end_of_window to nonzero. Tue Jun 25 05:25:33 1985 Richard M. Stallman (rms at mit-prep) * cmds.c (Fnewline): Call the auto fill hook if appropriate. * xdisp.c (try_window_id): If point is found by compute_motion after xp, record that permanently. If display_text_line sets point position wrong (case where line is killed, point is at eob and that line is not displayed), set it again in final compute_motion. File: emacs, Node: Tags, Next: Fortran, Prev: Change Log, Up: Programs Tag Tables ========== A "tag table" is a description of how a multi-file program is broken up into files. It lists the names of the component files and the names and positions of the functions in each file. Grouping the related files makes it possible to search or replace through all the files with one command. Recording the function names and positions makes possible the `Meta-.' command which you can use to find the definition of a function without having to know which of the files it is in. Tag tables are stored in files called "tag table files". The conventional name for a tag table file is `TAGS'. Each entry in the tag table records the name of one tag, the name of the file that the tag is defined in (implicitly), and the position in that file of the tag's definition. Just what names from the described files are recorded in the tag table depends on the programming language of the described file. They normally include all functions and subroutines, and may also include global variables, data types, and anything else convenient. In any case, each name recorded is called a "tag". * Menu: * Tag Syntax:: * Create Tag Table:: * Select Tag Table:: * Find Tag:: * Tags Search:: * Tags Stepping:: * List Tags:: File: emacs, Node: Tag Syntax, Next: Create Tag Table, Prev: Tags, Up: Tags Source File Tag Syntax ---------------------- In Lisp code, any function defined with `defun', any variable defined with `defvar' or `defconst', and in general the first argument of any expression that starts with `(def' in column zero, is a tag. In C code, any C function is a tag, and so is any typedef if `-t' is specified when the tag table is constructed. In Fortran code, functions and subroutines are tags. In LaTeX text, the argument of any of the commands `\chapter', `\section', `\subsection', `\subsubsection', `\eqno', `\label', `\ref', `\cite', `\bibitem' and `\typeout' is a tag. File: emacs, Node: Create Tag Table, Next: Select Tag Table, Prev: Tag Syntax, Up: Tags Creating Tag Tables ------------------- The `etags' program is used to create a tag table file. It knows the syntax of C, Fortran, LaTeX, Scheme and Emacs Lisp/Common Lisp. To use `etags', type etags INPUTFILES... as a shell command. It reads the specified files and writes a tag table named `TAGS' in the current working directory. `etags' recognizes the language used in an input file based on its file name and contents; there are no switches for specifying the language. The `-t' switch tells `etags' to record typedefs in C code as tags. If the tag table data become outdated due to changes in the files described in the table, the way to update the tag table is the same way it was made in the first place. It is not necessary to do this often. If the tag table fails to record a tag, or records it for the wrong file, then Emacs cannot possibly find its definition. However, if the position recorded in the tag table becomes a little bit wrong (due to some editing in the file that the tag definition is in), the only consequence is to slow down finding the tag slightly. Even if the stored position is very wrong, Emacs will still find the tag, but it must search the entire file for it. So you should update a tag table when you define new tags that you want to have listed, or when you move tag definitions from one file to another, or when changes become substantial. Normally there is no need to update the tag table after each edit, or even every day. File: emacs, Node: Select Tag Table, Next: Find Tag, Prev: Create Tag Table, Up: Tags Selecting a Tag Table --------------------- Emacs has at any time one "selected" tag table, and all the commands for working with tag tables use the selected one. To select a tag table, type `M-x visit-tags-table', which reads the tag table file name as an argument. The name `TAGS' in the default directory is used as the default file name. All this command does is store the file name in the variable `tags-file-name'. Emacs does not actually read in the tag table contents until you try to use them. Setting this variable yourself is just as good as using `visit-tags-table'. The variable's initial value is `nil'; this value tells all the commands for working with tag tables that they must ask for a tag table file name to use. File: emacs, Node: Find Tag, Next: Tags Search, Prev: Select Tag Table, Up: Tags Finding a Tag ------------- The most important thing that a tag table enables you to do is to find the definition of a specific tag. `M-. TAG' Find first definition of TAG (`find-tag'). `C-u M-.' Find next alternate definition of last tag specified. `C-x 4 . TAG' Find first definition of TAG, but display it in another window (`find-tag-other-window'). `M-.' (`find-tag') is the command to find the definition of a specified tag. It searches through the tag table for that tag, as a string, and then uses the tag table info to determine the file that the definition is in and the approximate character position in the file of the definition. Then `find-tag' visits that file, moves point to the approximate character position, and starts searching ever-increasing distances away for the the text that should appear at the beginning of the definition. If an empty argument is given (just type RET), the sexp in the buffer before or around point is used as the name of the tag to find. *Note Lists::, for info on sexps. The argument to `find-tag' need not be the whole tag name; it can be a substring of a tag name. However, there can be many tag names containing the substring you specify. Since `find-tag' works by searching the text of the tag table, it finds the first tag in the table that the specified substring appears in. The way to find other tags that match the substring is to give `find-tag' a numeric argument, as in `C-u M-.'; this does not read a tag name, but continues searching the tag table's text for another tag containing the same substring last used. If you have a real META key, `M-0 M-.' is an easier alternative to `C-u M-.'. (That is a zero in `M-0'.) Like most commands that can switch buffers, `find-tag' has another similar command that displays the new buffer in another window. `C-x 4 .' invokes the function `find-tag-other-window'. (This key sequence ends with a period.) Emacs comes with a tag table file `TAGS', in the `src' subdirectory, which includes all the Lisp libraries and all the C sources of Emacs. By specifying this file with `visit-tags-table' and then using `M-.' you can quickly look at the source of any Emacs function. File: emacs, Node: Tags Search, Next: Tags Stepping, Prev: Find Tag, Up: Tags Searching and Replacing with Tag Tables --------------------------------------- The commands in this section visit and search all the files listed in the selected tag table, one by one. For these commands, the tag table serves only to specify a sequence of files to search. A related command is `M-x grep' (*note Compilation::.). `M-x tags-search' Search for the specified regexp through the files in the selected tag table. `M-x tags-query-replace' Perform a `query-replace' on each file in the selected tag table. `M-,' Restart one of the commands above, from the current location of point (`tags-loop-continue'). `M-x tags-search' reads a regexp using the minibuffer, then visits the files of the selected tag table one by one, and searches through each one for that regexp. It displays the name of the file being searched so you can follow its progress. As soon as an occurrence is found, `tags-search' returns. Having found one match, you probably want to find all the rest. To find one more match, type `M-,' (`tags-loop-continue') to resume the `tags-search'. This searches the rest of the current buffer, followed by the remaining files of the tag table. `M-x tags-query-replace' performs a single `query-replace' through all the files in the tag table. It reads a string to search for and a string to replace with, just like ordinary `M-x query-replace'. It searches much like `M-x tags-search' but repeatedly, processing matches according to your input. *Note Replace::, for more information on `query-replace'. It is possible to get through all the files in the tag table with a single invocation of `M-x tags-query-replace'. But since any unrecognized character causes the command to exit, you may need to continue where you left off. `M-,' can be used for this. It resumes the last tags search or replace command that you did. It may have struck you that `tags-search' is a lot like `grep'. You can also run `grep' itself as an inferior of Emacs and have Emacs show you the matching lines one by one. This works mostly the same as running a compilation and having Emacs show you where the errors were. *Note Compilation::. File: emacs, Node: Tags Stepping, Next: List Tags, Prev: Tags Search, Up: Tags Stepping Through a Tag Table ---------------------------- If you wish to process all the files in the selected tag table, but `M-x tags-search' and `M-x tags-query-replace' in particular are not what you want, you can use `M-x next-file'. `C-u M-x next-file' With a numeric argument, regardless of its value, visit the first file in the tag table, and prepare to advance sequentially by files. `M-x next-file' Visit the next file in the selected tag table. File: emacs, Node: List Tags, Prev: Tags Stepping, Up: Tags Tag Table Inquiries ------------------- `M-x list-tags' Display a list of the tags defined in a specific program file. `M-x tags-apropos' Display a list of all tags matching a specified regexp. `M-x list-tags' reads the name of one of the files described by the selected tag table, and displays a list of all the tags defined in that file. The "file name" argument is really just a string to compare against the names recorded in the tag table; it is read as a string rather than as a file name. Therefore, completion and defaulting are not available, and you must enter the string the same way it appears in the tag table. Do not include a directory as part of the file name unless the file name recorded in the tag table includes a directory. `M-x tags-apropos' is like `apropos' for tags. It reads a regexp, then finds all the tags in the selected tag table whose entries match that regexp, and displays the tag names found. File: emacs, Node: Fortran, Prev: Tags, Up: Programs Fortran Mode ============ Fortran mode provides special motion commands for Fortran statements and subprograms, and indentation commands that understand Fortran conventions of nesting, line numbers and continuation statements. Special commands for comments are provided because Fortran comments are unlike those of other languages. Built-in abbrevs optionally save typing when you insert Fortran keywords. Use `M-x fortran-mode' to switch to this major mode. Doing so calls the value of `fortran-mode-hook' as a function of no arguments if that variable has a value that is not `nil'. * Menu: * Motion: Fortran Motion. Moving point by statements or subprograms. * Indent: Fortran Indent. Indentation commands for Fortran. * Comments: Fortran Comments. Inserting and aligning comments. * Columns: Fortran Columns. Measuring columns for valid Fortran. * Abbrev: Fortran Abbrev. Built-in abbrevs for Fortran keywords. Fortran mode was contributed by Michael Prange. File: emacs, Node: Fortran Motion, Next: Fortran Indent, Prev: Fortran, Up: Fortran Motion Commands --------------- Fortran mode provides special commands to move by subprograms (functions and subroutines) and by statements. There is also a command to put the region around one subprogram, convenient for killing it or moving it. `C-M-a' Move to beginning of subprogram (`beginning-of-fortran-subprogram'). `C-M-e' Move to end of subprogram (`end-of-fortran-subprogram'). `C-M-h' Put point at beginning of subprogram and mark at end (`mark-fortran-subprogram'). `C-c C-n' Move to beginning of current or next statement (`fortran-next-statement'). `C-c C-p' Move to beginning of current or previous statement (`fortran-previous-statement'). File: emacs, Node: Fortran Indent, Next: Fortran Comments, Prev: Fortran Motion, Up: Fortran Fortran Indentation ------------------- Special commands and features are needed for indenting Fortran code in order to make sure various syntactic entities (line numbers, comment line indicators and continuation line flags) appear in the columns that are required for standard Fortran. * Menu: * Commands: ForIndent Commands. Commands for indenting Fortran. * Numbers: ForIndent Num. How line numbers auto-indent. * Conv: ForIndent Conv. Conventions you must obey to avoid trouble. * Vars: ForIndent Vars. Variables controlling Fortran indent style. File: emacs, Node: ForIndent Commands, Next: ForIndent Num, Prev: Fortran Indent, Up: Fortran Indent Fortran Indentation Commands ............................ `TAB' Indent the current line (`fortran-indent-line'). `M-LFD' Break the current line and set up a continuation line. `C-M-q' Indent all the lines of the subprogram point is in (`fortran-indent-subprogram'). TAB is redefined by Fortran mode to reindent the current line for Fortran (`fortran-indent-line'). Line numbers and continuation markers are indented to their required columns, and the body of the statement is independently indented based on its nesting in the program. The key `C-M-q' is redefined as `fortran-indent-subprogram', a command to reindent all the lines of the Fortran subprogram (function or subroutine) containing point. The key `M-LFD' is redefined as `fortran-split-line', a command to split a line in the appropriate fashion for Fortran. In a non-comment line, the second half becomes a continuation line and is indented accordingly. In a comment line, both halves become separate comment lines. File: emacs, Node: ForIndent Num, Next: ForIndent Conv, Prev: ForIndent Commands, Up: Fortran Indent Line Numbers and Continuation ............................. If a number is the first non-whitespace in the line, it is assumed to be a line number and is moved to columns 0 through 4. (Columns are always counted from 0 in GNU Emacs.) If the text on the line starts with the conventional Fortran continuation marker `$', it is moved to column 5. If the text begins with any non whitespace character in column 5, it is assumed to be an unconventional continuation marker and remains in column 5. Line numbers of four digits or less are normally indented one space. This amount is controlled by the variable `fortran-line-number-indent' which is the maximum indentation a line number can have. Line numbers are indented to right-justify them to end in column 4 unless that would require more than this maximum indentation. The default value of the variable is 1. Simply inserting a line number is enough to indent it according to these rules. As each digit is inserted, the indentation is recomputed. To turn off this feature, set the variable `fortran-electric-line-number' to `nil'. Then inserting line numbers is like inserting anything else. File: emacs, Node: ForIndent Conv, Next: ForIndent Vars, Prev: ForIndent Num, Up: Fortran Indent Syntactic Conventions ..................... Fortran mode assumes that you follow certain conventions that simplify the task of understanding a Fortran program well enough to indent it properly: * Two nested `do' loops never share a `continue' statement. * The same character appears in column 5 of all continuation lines, and this character is the value of the variable `fortran-continuation-char'. By default, this character is `$'. If you fail to follow these conventions, the indentation commands may indent some lines unaesthetically. However, a correct Fortran program will retain its meaning when reindented even if the conventions are not followed. File: emacs, Node: ForIndent Vars, Prev: ForIndent Conv, Up: Fortran Indent Variables for Fortran Indentation ................................. Several additional variables control how Fortran indentation works. `fortran-do-indent' Extra indentation within each level of `do' statement (default 3). `fortran-if-indent' Extra indentation within each level of `if' statement (default 3). `fortran-continuation-indent' Extra indentation for bodies of continuation lines (default 5). `fortran-check-all-num-for-matching-do' If this is `nil', indentation assumes that each `do' statement ends on a `continue' statement. Therefore, when computing indentation for a statement other than `continue', it can save time by not checking for a `do' statement ending there. If this is non-`nil', indenting any numbered statement must check for a `do' that ends there. The default is `nil'. `fortran-minimum-statement-indent' Minimum indentation for fortran statements. For standard Fortran, this is 6. Statement bodies will never be indented less than this much. File: emacs, Node: Fortran Comments, Next: Fortran Columns, Prev: Fortran Indent, Up: Fortran Comments -------- The usual Emacs comment commands assume that a comment can follow a line of code. In Fortran, the standard comment syntax requires an entire line to be just a comment. Therefore, Fortran mode replaces the standard Emacs comment commands and defines some new variables. Fortran mode can also handle a nonstandard comment syntax where comments start with `!' and can follow other text. Because only some Fortran compilers accept this syntax, Fortran mode will not insert such comments unless you have said in advance to do so. To do this, set the variable `comment-start' to `"!"' (*note Variables::.). `M-;' Align comment or insert new comment (`fortran-comment-indent'). `C-x ;' Applies to nonstandard `!' comments only. `C-c ;' Turn all lines of the region into comments, or (with arg) turn them back into real code (`fortran-comment-region'). `M-;' in Fortran mode is redefined as the command `fortran-comment-indent'. Like the usual `M-;' command, this recognizes any kind of existing comment and aligns its text appropriately; if there is no existing comment, a comment is inserted and aligned. But inserting and aligning comments are not the same in Fortran mode as in other modes. When a new comment must be inserted, if the current line is blank, a full-line comment is inserted. On a non-blank line, a nonstandard `!' comment is inserted if you have said you want to use them. Otherwise a full-line comment is inserted on a new line before the current line. Nonstandard `!' comments are aligned like comments in other languages, but full-line comments are different. In a standard full-line comment, the comment delimiter itself must always appear in column zero. What can be aligned is the text within the comment. You can choose from three styles of alignment by setting the variable `fortran-comment-indent-style' to one of these values: `fixed' The text is aligned at a fixed column, which is the value of `fortran-comment-line-column'. This is the default. `relative' The text is aligned as if it were a line of code, but with an additional `fortran-comment-line-column' columns of indentation. `nil' Text in full-line columns is not moved automatically. In addition, you can specify the character to be used to indent within full-line comments by setting the variable `fortran-comment-indent-char' to the character you want to use. Fortran mode introduces the two variables, `comment-line-start' and `comment-line-start-skip', which play for full-line comments the same roles played by `comment-start' and `comment-start-skip' for ordinary text-following comments. Normally these are set properly by Fortran mode so you do not need to change them. The normal Emacs comment command `C-x ;' has not been redefined. If you use `!' comments, this command can be used with them. Otherwise it is useless in Fortran mode. The command `C-c ;' (`fortran-comment-region') turns all the lines of the region into comments by inserting the string `C$$$' at the front of each one. With a numeric arg, the region is turned back into live code by deleting `C$$$' from the front of each line in it. The string used for these comments can be controlled by setting the variable `fortran-comment-region'. Note that here we have an example of a command and a variable with the same name; these two uses of the name never conflict because in Lisp and in Emacs it is always clear from the context which one is meant. File: emacs, Node: Fortran Columns, Next: Fortran Abbrev, Prev: Fortran Comments, Up: Fortran Columns ------- `C-c C-r' Displays a "column ruler" momentarily above the current line (`fortran-column-ruler'). `C-c C-w' Splits the current window horizontally so that it is 72 columns wide. This may help you avoid going over that limit (`fortran-window-create'). The command `C-c C-r' (`fortran-column-ruler') shows a column ruler momentarily above the current line. The comment ruler is two lines of text that show you the locations of columns with special significance in Fortran programs. Square brackets show the limits of the columns for line numbers, and curly brackets show the limits of the columns for the statement body. Column numbers appear above them. Note that the column numbers count from zero, as always in GNU Emacs. As a result, the numbers may not be those you are familiar with; but the actual positions in the line are standard Fortran. The text used to display the column ruler is the value of the variable `fortran-comment-ruler'. By changing this variable, you can change the display. For even more help, use `C-c C-w' (`fortran-window-create'), a command which splits the current window horizontally, making a window 72 columns wide. By editing in this window you can immediately see when you make a line too wide to be correct Fortran. File: emacs, Node: Fortran Abbrev, Prev: Fortran Columns, Up: Fortran Fortran Keyword Abbrevs ----------------------- Fortran mode provides many built-in abbrevs for common keywords and declarations. These are the same sort of abbrev that you can define yourself. To use them, you must turn on Abbrev mode (*note Abbrevs::.). The built-in abbrevs are unusual in one way: they all start with a semicolon. You cannot normally use semicolons in an abbrev, but Fortran mode makes this possible by changing the syntax of semicolon to "word constituent". For example, one built-in Fortran abbrev is `;c' for `continue'. If you insert `;c' and then insert a punctuation character such as a space or a newline, the `;c' will change automatically to `continue', provided Abbrev mode is enabled. Type `;?' or `;C-h' to display a list of all the built-in Fortran abbrevs and what they stand for. File: emacs, Node: Compiling/Testing, Next: Abbrevs, Prev: Programs, Up: Top Compiling and Testing Programs ****************************** The previous chapter discusses the Emacs commands that are useful for making changes in programs. This chapter deals with commands that assist in the larger process of developing and maintaining programs. * Menu: * Compilation:: Compiling programs in languages other than Lisp (C, Pascal, etc.) * Modes: Lisp Modes. Various modes for editing Lisp programs, with different facilities for running the Lisp programs. * Libraries: Lisp Libraries. Creating Lisp programs to run in Emacs. * Interaction: Lisp Interaction. Executing Lisp in an Emacs buffer. * Eval: Lisp Eval. Executing a single Lisp expression in Emacs. * Debug: Lisp Debug. Debugging Lisp programs running in Emacs. * External Lisp:: Communicating through Emacs with a separate Lisp. File: emacs, Node: Compilation, Next: Lisp Modes, Prev: Compiling/Testing, Up: Compiling/Testing Running `make', or Compilers Generally ====================================== Emacs can run compilers for noninteractive languages such as C and Fortran as inferior processes, feeding the error log into an Emacs buffer. It can also parse the error messages and visit the files in which errors are found, moving point right to the line where the error occurred. `M-x compile' Run a compiler asynchronously under Emacs, with error messages to `*compilation*' buffer. `M-x grep' Run `grep' asynchronously under Emacs, with matching lines listed in the buffer named `*compilation*'. `M-x kill-compilation' `M-x kill-grep' Kill the running compilation or `grep' subprocess. `C-x `' Visit the locus of the next compiler error message or `grep' match. To run `make' or another compiler, do `M-x compile'. This command reads a shell command line using the minibuffer, and then executes the specified command line in an inferior shell with output going to the buffer named `*compilation*'. The current buffer's default directory is used as the working directory for the execution of the command; normally, therefore, the makefile comes from this directory. When the shell command line is read, the minibuffer appears containing a default command line, which is the command you used the last time you did `M-x compile'. If you type just RET, the same command line is used again. The first `M-x compile' provides `make -k' as the default. The default is taken from the variable `compile-command'; if the appropriate compilation command for a file is something other than `make -k', it can be useful to have the file specify a local value for `compile-command' (*note File Variables::.). Starting a compilation causes the buffer `*compilation*' to be displayed in another window but not selected. Its mode line tells you whether compilation is finished, with the word `run' or `exit' inside the parentheses. You do not have to keep this buffer visible; compilation continues in any case. To kill the compilation process, do `M-x kill-compilation'. You will see that the mode line of the `*compilation*' buffer changes to say `signal' instead of `run'. Starting a new compilation also kills any running compilation, as only one can exist at any time. However, this requires confirmation before actually killing a compilation that is running. To parse the compiler error messages, type `C-x `' (`next-error'). The character following the `C-x' is the grave accent, not the single quote. This command displays the buffer `*compilation*' in one window and the buffer in which the next error occurred in another window. Point in that buffer is moved to the line where the error was found. The corresponding error message is scrolled to the top of the window in which `*compilation*' is displayed. The first time `C-x `' is used after the start of a compilation, it parses all the error messages, visits all the files that have error messages, and makes markers pointing at the lines that the error messages refer to. Then it moves to the first error message location. Subsequent uses of `C-x `' advance down the data set up by the first use. When the preparsed error messages are exhausted, the next `C-x `' checks for any more error messages that have come in; this is useful if you start editing the compiler errors while the compilation is still going on. If no more error messages have come in, `C-x `' reports an error. `C-u C-x `' discards the preparsed error message data and parses the `*compilation*' buffer over again, then displaying the first error. This way, you can process the same set of errors again. Instead of running a compiler, you can run `grep' and see the lines on which matches were found. To do this, type `M-x grep' with an argument line that contains the same arguments you would give `grep' when running it normally: a `grep'-style regexp (usually in singlequotes to quote the shell's special characters) followed by filenames which may use wildcards. The output from `grep' goes in the `*compilation*' buffer and the lines that matched can be found with `C-x `' as if they were compilation errors. Note: a shell is used to run the compile command, but the shell is told that it should be noninteractive. This means in particular that the shell starts up with no prompt. If you find your usual shell prompt making an unsightly appearance in the `*compilation*' buffer, it means you have made a mistake in your shell's init file (`.cshrc' or `.shrc' or ...) by setting the prompt unconditionally. The shell init file should set the prompt only if there already is a prompt. Here is how to do it in `csh': if ($?prompt) set prompt = ... Here is how to do it in the Bourne-Again shell: if [ ! "$PS1" ]; then PS1=... fi File: emacs, Node: Lisp Modes, Next: Lisp Libraries, Prev: Compilation, Up: Compiling/Testing Major Modes for Lisp ==================== Emacs has four different major modes for Lisp. They are the same in terms of editing commands, but differ in the commands for executing Lisp expressions. Emacs-Lisp mode The mode for editing source files of programs to run in Emacs Lisp. This mode defines `C-M-x' to evaluate the current defun. *Note Lisp Libraries::. Lisp Interaction mode The mode for an interactive session with Emacs Lisp. It defines LFD to evaluate the sexp before point and insert its value in the buffer. *Note Lisp Interaction::. Lisp mode The mode for editing source files of programs that run in Lisps other than Emacs Lisp. This mode defines `C-M-x' to send the current defun to an inferior Lisp process. *Note External Lisp::. Inferior Lisp mode The mode for an interactive session with an inferior Lisp process. This mode combines the special features of Lisp mode and Shell mode (*note Shell Mode::.). Scheme mode Like Lisp mode but for Scheme programs. Inferior Scheme mode The mode for an interactive session with an inferior Scheme process. File: emacs, Node: Lisp Libraries, Next: Lisp Eval, Prev: Lisp Modes, Up: Compiling/Testing Libraries of Lisp Code for Emacs ================================ Lisp code for Emacs editing commands is stored in files whose names conventionally end in `.el'. This ending tells Emacs to edit them in Emacs-Lisp mode (*note Lisp Modes::.). * Menu: * Loading:: Loading libraries of Lisp code into Emacs for use. * Compiling Libraries:: Compiling a library makes it load and run faster. * Mocklisp:: Converting Mocklisp to Lisp so GNU Emacs can run it. File: emacs, Node: Loading, Next: Compiling Libraries, Prev: Lisp Libraries, Up: Lisp Libraries Loading Libraries ----------------- To execute a file of Emacs Lisp, use `M-x load-file'. This command reads a file name using the minibuffer and then executes the contents of that file as Lisp code. It is not necessary to visit the file first; in any case, this command reads the file as found on disk, not text in an Emacs buffer. Once a file of Lisp code is installed in the Emacs Lisp library directories, users can load it using `M-x load-library'. Programs can load it by calling `load-library', or with `load', a more primitive function that is similar but accepts some additional arguments. `M-x load-library' differs from `M-x load-file' in that it searches a sequence of directories and tries three file names in each directory. The three names are, first, the specified name with `.elc' appended; second, with `.el' appended; third, the specified name alone. A `.elc' file would be the result of compiling the Lisp file into byte code; it is loaded if possible in preference to the Lisp file itself because the compiled file will load and run faster. Because the argument to `load-library' is usually not in itself a valid file name, file name completion is not available. Indeed, when using this command, you usually do not know exactly what file name will be used. The sequence of directories searched by `M-x load-library' is specified by the variable `load-path', a list of strings that are directory names. The default value of the list contains the directory where the Lisp code for Emacs itself is stored. If you have libraries of your own, put them in a single directory and add that directory to `load-path'. `nil' in this list stands for the current default directory, but it is probably not a good idea to put `nil' in the list. If you find yourself wishing that `nil' were in the list, most likely what you really want to do is use `M-x load-file' this once. Often you do not have to give any command to load a library, because the commands defined in the library are set up to "autoload" that library. Running any of those commands causes `load' to be called to load the library; this replaces the autoload definitions with the real ones from the library. If autoloading a file does not finish, either because of an error or because of a `C-g' quit, all function definitions made by the file are undone automatically. So are any calls to `provide'. As a consequence, if you use one of the autoloadable commands again, the entire file will be loaded a second time. This prevents problems where the command is no longer autoloading but it works wrong because not all the file was loaded. Function definitions are undone only for autoloading; explicit calls to `load' do not undo anything if loading is not completed. File: emacs, Node: Compiling Libraries, Next: Mocklisp, Prev: Loading, Up: Lisp Libraries Compiling Libraries ------------------- Emacs Lisp code can be compiled into byte-code which loads faster, takes up less space when loaded, and executes faster. The way to make a byte-code compiled file from an Emacs-Lisp source file is with `M-x byte-compile-file'. The default argument for this function is the file visited in the current buffer. It reads the specified file, compiles it into byte code, and writes an output file whose name is made by appending `c' to the input file name. Thus, the file `rmail.el' would be compiled into `rmail.elc'. To recompile the changed Lisp files in a directory, use `M-x byte-recompile-directory'. Specify just the directory name as an argument. Each `.el' file that has been byte-compiled before is byte-compiled again if it has changed since the previous compilation. A numeric argument to this command tells it to offer to compile each `.el' file that has not already been compiled. You must answer `y' or `n' to each offer. Emacs can be invoked noninteractively from the shell to do byte compilation with the aid of the function `batch-byte-compile'. In this case, the files to be compiled are specified with command-line arguments. Use a shell command of the form emacs -batch -f batch-byte-compile FILES... Directory names may also be given as arguments; `byte-recompile-directory' is invoked (in effect) on each such directory. `batch-byte-compile' uses all the remaining command-line arguments as file or directory names, then kills the Emacs process. `M-x disassemble' explains the result of byte compilation. Its argument is a function name. It displays the byte-compiled code in a help window in symbolic form, one instruction per line. If the instruction refers to a variable or constant, that is shown too. File: emacs, Node: Mocklisp, Prev: Compiling Libraries, Up: Lisp Libraries Converting Mocklisp to Lisp --------------------------- GNU Emacs can run Mocklisp files by converting them to Emacs Lisp first. To convert a Mocklisp file, visit it and then type `M-x convert-mocklisp-buffer'. Then save the resulting buffer of Lisp file in a file whose name ends in `.el' and use the new file as a Lisp library. It does not currently work to byte-compile converted Mocklisp code. This is because converted Mocklisp code uses some special Lisp features to deal with Mocklisp's incompatible ideas of how arguments are evaluated and which values signify "true" or "false".