home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Acorn User 10
/
AU_CD10.iso
/
Updates
/
Perl
/
RPC
/
Docs
/
perldelta
< prev
next >
Wrap
Text File
|
1999-04-17
|
39KB
|
1,022 lines
NAME
perldelta - what's new for perl5.005
DESCRIPTION
This document describes differences between the 5.004 release
and this one.
About the new versioning system
Perl is now developed on two tracks: a maintenance track that
makes small, safe updates to released production versions with
emphasis on compatibility; and a development track that pursues
more aggressive evolution. Maintenance releases (which should be
considered production quality) have subversion numbers that run
from `1' to `49', and development releases (which should be
considered "alpha" quality) run from `50' to `99'.
Perl 5.005 is the combined product of the new dual-track
development scheme.
Incompatible Changes
WARNING: This version is not binary compatible with Perl 5.004.
Starting with Perl 5.004_50 there were many deep and far-
reaching changes to the language internals. If you have
dynamically loaded extensions that you built under perl 5.003 or
5.004, you can continue to use them with 5.004, but you will
need to rebuild and reinstall those extensions to use them
5.005. See the INSTALL manpage for detailed instructions on how
to upgrade.
Default installation structure has changed
The new Configure defaults are designed to allow a smooth
upgrade from 5.004 to 5.005, but you should read the INSTALL
manpage for a detailed discussion of the changes in order to
adapt them to your system.
Perl Source Compatibility
When none of the experimental features are enabled, there should
be very few user-visible Perl source compatibility issues.
If threads are enabled, then some caveats apply. `@_' and `$_'
become lexical variables. The effect of this should be largely
transparent to the user, but there are some boundary conditions
under which user will need to be aware of the issues. For
example, `local(@_)' results in a "Can't localize lexical
variable @_ ..." message. This may be enabled in a future
version.
Some new keywords have been introduced. These are generally
expected to have very little impact on compatibility. See the
New `INIT' keyword manpage, the New `lock' keyword manpage, and
the "/' operator" entry in the New `qr manpage.
Certain barewords are now reserved. Use of these will provoke a
warning if you have asked for them with the `-w' switch. See the
`our' is now a reserved word manpage.
C Source Compatibility
There have been a large number of changes in the internals to
support the new features in this release.
Core sources now require ANSI C compiler
An ANSI C compiler is now required to build perl. See
INSTALL.
All Perl global variables must now be referenced with an explicit prefix
All Perl global variables that are visible for use by
extensions now have a `PL_' prefix. New extensions should
`not' refer to perl globals by their unqualified names. To
preserve sanity, we provide limited backward compatibility
for globals that are being widely used like `sv_undef' and
`na' (which should now be written as `PL_sv_undef', `PL_na'
etc.)
If you find that your XS extension does not compile anymore
because a perl global is not visible, try adding a `PL_'
prefix to the global and rebuild.
It is strongly recommended that all functions in the Perl
API that don't begin with `perl' be referenced with a
`Perl_' prefix. The bare function names without the `Perl_'
prefix are supported with macros, but this support may cease
in a future release.
See the section on "API LISTING" in the perlguts manpage.
Enabling threads has source compatibility issues
Perl built with threading enabled requires extensions to use
the new `dTHR' macro to initialize the handle to access per-
thread data. If you see a compiler error that talks about
the variable `thr' not being declared (when building a
module that has XS code), you need to add `dTHR;' at the
beginning of the block that elicited the error.
The API function `perl_get_sv("@",FALSE)' should be used
instead of directly accessing perl globals as `GvSV(errgv)'.
The API call is backward compatible with existing perls and
provides source compatibility with threading is enabled.
See the section on "C Source Compatibility" for more
information.
Binary Compatibility
This version is NOT binary compatible with older versions. All
extensions will need to be recompiled. Further binaries built
with threads enabled are incompatible with binaries built
without. This should largely be transparent to the user, as all
binary incompatible configurations have their own unique
architecture name, and extension binaries get installed at
unique locations. This allows coexistence of several
configurations in the same directory hierarchy. See INSTALL.
Security fixes may affect compatibility
A few taint leaks and taint omissions have been corrected. This
may lead to "failure" of scripts that used to work with older
versions. Compiling with -DINCOMPLETE_TAINTS provides a perl
with minimal amounts of changes to the tainting behavior. But
note that the resulting perl will have known insecurities.
Oneliners with the `-e' switch do not create temporary files
anymore.
Relaxed new mandatory warnings introduced in 5.004
Many new warnings that were introduced in 5.004 have been made
optional. Some of these warnings are still present, but perl's
new features make them less often a problem. See the New
Diagnostics manpage.
Licensing
Perl has a new Social Contract for contributors. See
Porting/Contract.
The license included in much of the Perl documentation has
changed. Most of the Perl documentation was previously under the
implicit GNU General Public License or the Artistic License (at
the user's choice). Now much of the documentation unambigously
states the terms under which it may be distributed. Those terms
are in general much less restrictive than the GNU GPL. See the
perl manpage and the individual perl man pages listed therein.
Core Changes
Threads
WARNING: Threading is considered an experimental feature.
Details of the implementation may change without notice. There
are known limitations and some bugs. These are expected to be
fixed in future versions.
See the README.threads manpage.
Mach cthreads (NEXTSTEP, OPENSTEP, Rhapsody) are now supported
by the Thread extension.
Compiler
WARNING: The Compiler and related tools are considered
experimental. Features may change without notice, and there are
known limitations and bugs. Since the compiler is fully external
to perl, the default configuration will build and install it.
The Compiler produces three different types of transformations
of a perl program. The C backend generates C code that captures
perl's state just before execution begins. It eliminates the
compile-time overheads of the regular perl interpreter, but the
run-time performance remains comparatively the same. The CC
backend generates optimized C code equivalent to the code path
at run-time. The CC backend has greater potential for big
optimizations, but only a few optimizations are implemented
currently. The Bytecode backend generates a platform independent
bytecode representation of the interpreter's state just before
execution. Thus, the Bytecode back end also eliminates much of
the compilation overhead of the interpreter.
The compiler comes with several valuable utilities.
`B::Lint' is an experimental module to detect and warn about
suspicious code, especially the cases that the `-w' switch does
not detect.
`B::Deparse' can be used to demystify perl code, and understand
how perl optimizes certain constructs.
`B::Xref' generates cross reference reports of all definition
and use of variables, subroutines and formats in a program.
`B::Showlex' show the lexical variables used by a subroutine or
file at a glance.
`perlcc' is a simple frontend for compiling perl.
See `ext/B/README', the B manpage, and the respective compiler
modules.
Regular Expressions
Perl's regular expression engine has been seriously overhauled,
and many new constructs are supported. Several bugs have been
fixed.
Here is an itemized summary:
Many new and improved optimizations
Changes in the RE engine:
Unneeded nodes removed;
Substrings merged together;
New types of nodes to process (SUBEXPR)* and similar expressions
quickly, used if the SUBEXPR has no side effects and matches
strings of the same length;
Better optimizations by lookup for constant substrings;
Better search for constants substrings anchored by $ ;
Changes in Perl code using RE engine:
More optimizations to s/longer/short/;
study() was not working;
/blah/ may be optimized to an analogue of index() if $& $` $' not seen;
Unneeded copying of matched-against string removed;
Only matched part of the string is copying if $` $' were not seen;
Many bug fixes
Note that only the major bug fixes are listed here. See
Changes for others.
Backtracking might not restore start of $3.
No feedback if max count for * or + on "complex" subexpression
was reached, similarly (but at compile time) for {3,34567}
Primitive restrictions on max count introduced to decrease a
possibility of a segfault;
(ZERO-LENGTH)* could segfault;
(ZERO-LENGTH)* was prohibited;
Long REs were not allowed;
/RE/g could skip matches at the same position after a
zero-length match;
New regular expression constructs
The following new syntax elements are supported:
(?<=RE)
(?<!RE)
(?{ CODE })
(?i-x)
(?i:RE)
(?(COND)YES_RE|NO_RE)
(?>RE)
\z
New operator for precompiled regular expressions
See the "/' operator" entry in the New `qr manpage.
Other improvements
Better debugging output (possibly with colors),
even from non-debugging Perl;
RE engine code now looks like C, not like assembler;
Behaviour of RE modifiable by `use re' directive;
Improved documentation;
Test suite significantly extended;
Syntax [:^upper:] etc., reserved inside character classes;
Incompatible changes
(?i) localized inside enclosing group;
$( is not interpolated into RE any more;
/RE/g may match at the same position (with non-zero length)
after a zero-length match (bug fix).
See the perlre manpage and the perlop manpage.
Improved malloc()
See banner at the beginning of `malloc.c' for details.
Quicksort is internally implemented
Perl now contains its own highly optimized qsort() routine. The
new qsort() is resistant to inconsistent comparison functions,
so Perl's `sort()' will not provoke coredumps any more when
given poorly written sort subroutines. (Some C library
`qsort()'s that were being used before used to have this
problem.) In our testing, the new `qsort()' required the minimal
number of pair-wise compares on average, among all known
`qsort()' implementations.
See `perlfunc/sort'.
Reliable signals
Perl's signal handling is susceptible to random crashes, because
signals arrive asynchronously, and the Perl runtime is not
reentrant at arbitrary times.
However, one experimental implementation of reliable signals is
available when threads are enabled. See `Thread::Signal'. Also
see INSTALL for how to build a Perl capable of threads.
Reliable stack pointers
The internals now reallocate the perl stack only at predictable
times. In particular, magic calls never trigger reallocations of
the stack, because all reentrancy of the runtime is handled
using a "stack of stacks". This should improve reliability of
cached stack pointers in the internals and in XSUBs.
More generous treatment of carriage returns
Perl used to complain if it encountered literal carriage returns
in scripts. Now they are mostly treated like whitespace within
program text. Inside string literals and here documents, literal
carriage returns are ignored if they occur paired with
linefeeds, or get interpreted as whitespace if they stand alone.
This behavior means that literal carriage returns in files
should be avoided. You can get the older, more compatible (but
less generous) behavior by defining the preprocessor symbol
`PERL_STRICT_CR' when building perl. Of course, all this has
nothing whatever to do with how escapes like `\r' are handled
within strings.
Note that this doesn't somehow magically allow you to keep all
text files in DOS format. The generous treatment only applies to
files that perl itself parses. If your C compiler doesn't allow
carriage returns in files, you may still be unable to build
modules that need a C compiler.
Memory leaks
`substr', `pos' and `vec' don't leak memory anymore when used in
lvalue context. Many small leaks that impacted applications that
embed multiple interpreters have been fixed.
Better support for multiple interpreters
The build-time option `-DMULTIPLICITY' has had many of the
details reworked. Some previously global variables that should
have been per-interpreter now are. With care, this allows
interpreters to call each other. See the `PerlInterp' extension
on CPAN.
Behavior of local() on array and hash elements is now well-defined
See the section on "Temporary Values via local()" in the perlsub
manpage.
`%!' is transparently tied to the the Errno manpage module
See the perlvar manpage, and the Errno manpage.
Pseudo-hashes are supported
See the perlref manpage.
`EXPR foreach EXPR' is supported
See the perlsyn manpage.
Keywords can be globally overridden
See the perlsub manpage.
`$^E' is meaningful on Win32
See the perlvar manpage.
`foreach (1..1000000)' optimized
`foreach (1..1000000)' is now optimized into a counting loop. It
does not try to allocate a 1000000-size list anymore.
`Foo::' can be used as implicitly quoted package name
Barewords caused unintuitive behavior when a subroutine with the
same name as a package happened to be defined. Thus, `new Foo
@args', use the result of the call to `Foo()' instead of `Foo'
being treated as a literal. The recommended way to write
barewords in the indirect object slot is `new Foo:: @args'. Note
that the method `new()' is called with a first argument of
`Foo', not `Foo::' when you do that.
`exists $Foo::{Bar::}' tests existence of a package
It was impossible to test for the existence of a package without
actually creating it before. Now `exists $Foo::{Bar::}' can be
used to test if the `Foo::Bar' namespace has been created.
Better locale support
See the perllocale manpage.
Experimental support for 64-bit platforms
Perl5 has always had 64-bit support on systems with 64-bit
longs. Starting with 5.005, the beginnings of experimental
support for systems with 32-bit long and 64-bit 'long long'
integers has been added. If you add -DUSE_LONG_LONG to your
ccflags in config.sh (or manually define it in perl.h) then perl
will be built with 'long long' support. There will be many
compiler warnings, and the resultant perl may not work on all
systems. There are many other issues related to third-party
extensions and libraries. This option exists to allow people to
work on those issues.
prototype() returns useful results on builtins
See the "prototype" entry in the perlfunc manpage.
Extended support for exception handling
`die()' now accepts a reference value, and `$@' gets set to that
value in exception traps. This makes it possible to propagate
exception objects. This is an undocumented experimental feature.
Re-blessing in DESTROY() supported for chaining DESTROY() methods
See the "Destructors" entry in the perlobj manpage.
All `printf' format conversions are handled internally
See the "printf" entry in the perlfunc manpage.
New `INIT' keyword
`INIT' subs are like `BEGIN' and `END', but they get run just
before the perl runtime begins execution. e.g., the Perl
Compiler makes use of `INIT' blocks to initialize and resolve
pointers to XSUBs.
New `lock' keyword
The `lock' keyword is the fundamental synchronization primitive
in threaded perl. When threads are not enabled, it is currently
a noop.
To minimize impact on source compatibility this keyword is
"weak", i.e., any user-defined subroutine of the same name
overrides it, unless a `use Thread' has been seen.
New `qr//' operator
The `qr//' operator, which is syntactically similar to the other
quote-like operators, is used to create precompiled regular
expressions. This compiled form can now be explicitly passed
around in variables, and interpolated in other regular
expressions. See the perlop manpage.
`our' is now a reserved word
Calling a subroutine with the name `our' will now provoke a
warning when using the `-w' switch.
Tied arrays are now fully supported
See the Tie::Array manpage.
Tied handles support is better
Several missing hooks have been added. There is also a new base
class for TIEARRAY implementations. See the Tie::Array manpage.
4th argument to substr
substr() can now both return and replace in one operation. The
optional 4th argument is the replacement string. See the
"substr" entry in the perlfunc manpage.
Negative LENGTH argument to splice
splice() with a negative LENGTH argument now work similar to
what the LENGTH did for substr(). Previously a negative LENGTH
was treated as 0. See the "splice" entry in the perlfunc
manpage.
Magic lvalues are now more magical
When you say something like `substr($x, 5) = "hi"', the scalar
returned by substr() is special, in that any modifications to it
affect $x. (This is called a 'magic lvalue' because an 'lvalue'
is something on the left side of an assignment.) Normally, this
is exactly what you would expect to happen, but Perl uses the
same magic if you use substr(), pos(), or vec() in a context
where they might be modified, like taking a reference with `\'
or as an argument to a sub that modifies `@_'. In previous
versions, this 'magic' only went one way, but now changes to the
scalar the magic refers to ($x in the above example) affect the
magic lvalue too. For instance, this code now acts differently:
$x = "hello";
sub printit {
$x = "g'bye";
print $_[0], "\n";
}
printit(substr($x, 0, 5));
In previous versions, this would print "hello", but it now
prints "g'bye".
<> now reads in records
If `$/' is a referenence to an integer, or a scalar that holds
an integer, <> will read in records instead of lines. For more
info, see the "$/" entry in the perlvar manpage.
pack() format 'Z' supported
The new format type 'Z' is useful for packing and unpacking
null-terminated strings. See the section on "pack" in the
perlfunc manpage.
Significant bug fixes
<HANDLE> on empty files
With `$/' set to `undef', slurping an empty file returns a
string of zero length (instead of `undef', as it used to) for
the first time the HANDLE is read. Subsequent reads yield
`undef'.
This means that the following will append "foo" to an empty file
(it used to not do anything before):
perl -0777 -pi -e 's/^/foo/' empty_file
Note that the behavior of:
perl -pi -e 's/^/foo/' empty_file
is unchanged (it continues to leave the file empty).
Supported Platforms
Configure has many incremental improvements. Site-wide policy
for building perl can now be made persistent, via Policy.sh.
Configure also records the command-line arguments used in
config.sh.
New Platforms
BeOS is now supported. See the README.beos manpage.
DOS is now supported under the DJGPP tools. See the README.dos
manpage.
GNU/Hurd is now supported.
MiNT is now supported. See the README.mint manpage.
MPE/iX is now supported. See the README.mpeix manpage.
MVS (aka OS390, aka Open Edition) is now supported. See the
README.os390 manpage.
Stratus VOS is now supported. See the README.vos manpage.
Changes in existing support
Win32 support has been vastly enhanced. Support for Perl Object,
a C++ encapsulation of Perl. GCC and EGCS are now supported on
Win32. See README.win32, aka the perlwin32 manpage.
VMS configuration system has been rewritten. See the README.vms
manpage.
The hints files for most Unix platforms have seen incremental
improvements.
Modules and Pragmata
New Modules
B Perl compiler and tools. See the B manpage.
Data::Dumper
A module to pretty print Perl data. See the Data::Dumper
manpage.
Dumpvalue
A module to dump perl values to the screen. See the
Dumpvalue manpage.
Errno
A module to look up errors more conveniently. See the Errno
manpage.
File::Spec
A portable API for file operations.
ExtUtils::Installed
Query and manage installed modules.
ExtUtils::Packlist
Manipulate .packlist files.
Fatal
Make functions/builtins succeed or die.
IPC::SysV
Constants and other support infrastructure for System V IPC
operations in perl.
Test
A framework for writing testsuites.
Tie::Array
Base class for tied arrays.
Tie::Handle
Base class for tied handles.
Thread
Perl thread creation, manipulation, and support.
attrs
Set subroutine attributes.
fields
Compile-time class fields.
re Various pragmata to control behavior of regular expressions.
Changes in existing modules
Benchmark
You can now run tests for *n* seconds instead of guessing
the right number of tests to run: e.g. timethese(-5, ...)
will run each of the codes for at least 5 CPU seconds. Zero
as the "number of repetitions" means "for at least 3 CPU
seconds". The output format has also changed. For example:
use Benchmark;$x=3;timethese(-
5,{a=>sub{$x*$x},b=>sub{$x**2}})
will now output something like this:
Benchmark: running a, b, each for at least 5 CPU seconds...
a: 5 wallclock secs ( 5.77 usr + 0.00 sys = 5.77 CPU) @
200551.91/s (n=1156516) b: 4 wallclock secs ( 5.00 usr +
0.02 sys = 5.02 CPU) @ 159605.18/s (n=800686)
New features: "each for at least N CPU seconds...",
"wallclock secs", and the "@ operations/CPU second
(n=operations)".
Carp
Carp has a new function cluck(). cluck() warns, like carp(),
but also adds a stack backtrace to the error message, like
confess().
CGI CGI has been updated to version 2.42.
Fcntl
More Fcntl constants added: F_SETLK64, F_SETLKW64,
O_LARGEFILE for large (more than 4G) file access (the 64-bit
support is not yet working, though, so no need to get overly
excited), Free/Net/OpenBSD locking behaviour flags F_FLOCK,
F_POSIX, Linux F_SHLCK, and O_ACCMODE: the mask of O_RDONLY,
O_WRONLY, and O_RDWR.
Math::Complex
The accessor methods Re, Im, arg, abs, rho, and theta, can
now also act as mutators (accessor $z->Re(), mutator $z-
>Re(3)).
Math::Trig
A little bit of radial trigonometry (cylindrical and
spherical) added: radial coordinate conversions and the
great circle distance.
POSIX
POSIX now has its own platform-specific hints files.
DB_File
DB_File supports version 2.x of Berkeley DB. See
`ext/DB_File/Changes'.
MakeMaker
MakeMaker now supports writing empty makefiles, provides a
way to specify that site umask() policy should be honored.
There is also better support for manipulation of .packlist
files, and getting information about installed modules.
Extensions that have both architecture-dependent and
architecture-independent files are now always installed
completely in the architecture-dependent locations.
Previously, the shareable parts were shared both across
architectures and across perl versions and were therefore
liable to be overwritten with newer versions that might have
subtle incompatibilities.
CPAN
See <perlmodinstall> and the CPAN manpage.
Cwd Cwd::cwd is faster on most platforms.
Benchmark
Keeps better time.
Utility Changes
`h2ph' and related utilities have been vastly overhauled.
`perlcc', a new experimental front end for the compiler is
available.
The crude GNU `configure' emulator is now called `configure.gnu'
to avoid trampling on `Configure' under case-insensitive
filesystems.
`perldoc' used to be rather slow. The slower features are now
optional. In particular, case-insensitive searches need the `-i'
switch, and recursive searches need `-r'. You can set these
switches in the `PERLDOC' environment variable to get the old
behavior.
Documentation Changes
Config.pm now has a glossary of variables.
Porting/patching.pod has detailed instructions on how to create
and submit patches for perl.
the perlport manpage specifies guidelines on how to write
portably.
the perlmodinstall manpage describes how to fetch and install
modules from `CPAN' sites.
Some more Perl traps are documented now. See the perltrap
manpage.
the perlopentut manpage gives a tutorial on using open().
the perlreftut manpage gives a tutorial on references.
the perlthrtut manpage gives a tutorial on threads.
New Diagnostics
Ambiguous call resolved as CORE::%s(), qualify as such or use &
(W) A subroutine you have declared has the same name as a
Perl keyword, and you have used the name without
qualification for calling one or the other. Perl decided to
call the builtin because the subroutine is not imported.
To force interpretation as a subroutine call, either put an
ampersand before the subroutine name, or qualify the name
with its package. Alternatively, you can import the
subroutine (or pretend that it's imported with the `use
subs' pragma).
To silently interpret it as the Perl operator, use the
`CORE::' prefix on the operator (e.g. `CORE::log($x)') or by
declaring the subroutine to be an object method (see the
attrs manpage).
Bad index while coercing array into hash
(F) The index looked up in the hash found as the 0'th
element of a pseudo-hash is not legal. Index values must be
at 1 or greater. See the perlref manpage.
Bareword "%s" refers to nonexistent package
(W) You used a qualified bareword of the form `Foo::', but
the compiler saw no other uses of that namespace before that
point. Perhaps you need to predeclare a package?
Can't call method "%s" on an undefined value
(F) You used the syntax of a method call, but the slot
filled by the object reference or package name contains an
undefined value. Something like this will reproduce the
error:
$BADREF = 42;
process $BADREF 1,2,3;
$BADREF->process(1,2,3);
Can't check filesystem of script "%s" for nosuid
(P) For some reason you can't check the filesystem of the
script for nosuid.
Can't coerce array into hash
(F) You used an array where a hash was expected, but the
array has no information on how to map from keys to array
indices. You can do that only with arrays that have a hash
reference at index 0.
Can't goto subroutine from an eval-string
(F) The "goto subroutine" call can't be used to jump out of
an eval "string". (You can use it to jump out of an eval
{BLOCK}, but you probably don't want to.)
Can't localize pseudo-hash element
(F) You said something like `local $ar->{'key'}', where $ar
is a reference to a pseudo-hash. That hasn't been
implemented yet, but you can get a similar effect by
localizing the corresponding array element directly --
`local $ar->[$ar->[0]{'key'}]'.
Can't use %%! because Errno.pm is not available
(F) The first time the %! hash is used, perl automatically
loads the Errno.pm module. The Errno module is expected to
tie the %! hash to provide symbolic names for `$!' errno
values.
Cannot find an opnumber for "%s"
(F) A string of a form `CORE::word' was given to
prototype(), but there is no builtin with the name `word'.
Character class syntax [. .] is reserved for future extensions
(W) Within regular expression character classes ([]) the
syntax beginning with "[." and ending with ".]" is reserved
for future extensions. If you need to represent those
character sequences inside a regular expression character
class, just quote the square brackets with the backslash:
"\[." and ".\]".
Character class syntax [: :] is reserved for future extensions
(W) Within regular expression character classes ([]) the
syntax beginning with "[:" and ending with ":]" is reserved
for future extensions. If you need to represent those
character sequences inside a regular expression character
class, just quote the square brackets with the backslash:
"\[:" and ":\]".
Character class syntax [= =] is reserved for future extensions
(W) Within regular expression character classes ([]) the
syntax beginning with "[=" and ending with "=]" is reserved
for future extensions. If you need to represent those
character sequences inside a regular expression character
class, just quote the square brackets with the backslash:
"\[=" and "=\]".
%s: Eval-group in insecure regular expression
(F) Perl detected tainted data when trying to compile a
regular expression that contains the `(?{ ... })' zero-width
assertion, which is unsafe. See the "(?{ code })" entry in
the perlre manpage, and the perlsec manpage.
%s: Eval-group not allowed, use re 'eval'
(F) A regular expression contained the `(?{ ... })' zero-
width assertion, but that construct is only allowed when the
`use re 'eval'' pragma is in effect. See the "(?{ code })"
entry in the perlre manpage.
%s: Eval-group not allowed at run time
(F) Perl tried to compile a regular expression containing
the `(?{ ... })' zero-width assertion at run time, as it
would when the pattern contains interpolated values. Since
that is a security risk, it is not allowed. If you insist,
you may still do this by explicitly building the pattern
from an interpolated string at run time and using that in an
eval(). See the "(?{ code })" entry in the perlre manpage.
Explicit blessing to '' (assuming package main)
(W) You are blessing a reference to a zero length string.
This has the effect of blessing the reference into the
package main. This is usually not what you want. Consider
providing a default target package, e.g. bless($ref, $p ||
'MyPackage');
Illegal hex digit ignored
(W) You may have tried to use a character other than 0 - 9
or A - F in a hexadecimal number. Interpretation of the
hexadecimal number stopped before the illegal character.
No such array field
(F) You tried to access an array as a hash, but the field
name used is not defined. The hash at index 0 should map all
valid field names to array indices for that to work.
No such field "%s" in variable %s of type %s
(F) You tried to access a field of a typed variable where
the type does not know about the field name. The field names
are looked up in the %FIELDS hash in the type package at
compile time. The %FIELDS hash is usually set up with the
'fields' pragma.
Out of memory during ridiculously large request
(F) You can't allocate more than 2^31+"small amount" bytes.
This error is most likely to be caused by a typo in the Perl
program. e.g., `$arr[time]' instead of `$arr[$time]'.
Range iterator outside integer range
(F) One (or both) of the numeric arguments to the range
operator ".." are outside the range which can be represented
by integers internally. One possible workaround is to force
Perl to use magical string increment by prepending "0" to
your numbers.
Recursive inheritance detected while looking for method '%s' in package '%s'
(F) More than 100 levels of inheritance were encountered
while invoking a method. Probably indicates an unintended
loop in your inheritance hierarchy.
Reference found where even-sized list expected
(W) You gave a single reference where Perl was expecting a
list with an even number of elements (for assignment to a
hash). This usually means that you used the anon hash
constructor when you meant to use parens. In any case, a
hash requires key/value pairs.
%hash = { one => 1, two => 2, }; # WRONG
%hash = [ qw/ an anon array / ]; # WRONG
%hash = ( one => 1, two => 2, ); # right
%hash = qw( one 1 two 2 ); # also fine
Undefined value assigned to typeglob
(W) An undefined value was assigned to a typeglob, a la
`*foo = undef'. This does nothing. It's possible that you
really mean `undef *foo'.
Use of reserved word "%s" is deprecated
(D) The indicated bareword is a reserved word. Future
versions of perl may use it as a keyword, so you're better
off either explicitly quoting the word in a manner
appropriate for its context of use, or using a different
name altogether. The warning can be suppressed for
subroutine names by either adding a `&' prefix, or using a
package qualifier, e.g. `&our()', or `Foo::our()'.
perl: warning: Setting locale failed.
(S) The whole warning message will look something like:
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LC_ALL = "En_US",
LANG = (unset)
are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
Exactly what were the failed locale settings varies. In the
above the settings were that the LC_ALL was "En_US" and the
LANG had no value. This error means that Perl detected that
you and/or your system administrator have set up the so-
called variable system but Perl could not use those
settings. This was not dead serious, fortunately: there is a
"default locale" called "C" that Perl can and will use, the
script will be run. Before you really fix the problem,
however, you will get the same error message each time you
run Perl. How to really fix the problem can be found in the
section on "LOCALE PROBLEMS" in the perllocale manpage.
Obsolete Diagnostics
Can't mktemp()
(F) The mktemp() routine failed for some reason while trying
to process a -e switch. Maybe your /tmp partition is full,
or clobbered.
Removed because -e doesn't use temporary files any more.
Can't write to temp file for -e: %s
(F) The write routine failed for some reason while trying to
process a -e switch. Maybe your /tmp partition is full, or
clobbered.
Removed because -e doesn't use temporary files any more.
Cannot open temporary file
(F) The create routine failed for some reason while trying
to process a -e switch. Maybe your /tmp partition is full,
or clobbered.
Removed because -e doesn't use temporary files any more.
regexp too big
(F) The current implementation of regular expressions uses
shorts as address offsets within a string. Unfortunately
this means that if the regular expression compiles to longer
than 32767, it'll blow up. Usually when you want a regular
expression this big, there is a better way to do it with
multiple statements. See the perlre manpage.
Configuration Changes
You can use "Configure -Uinstallusrbinperl" which causes
installperl to skip installing perl also as /usr/bin/perl. This
is useful if you prefer not to modify /usr/bin for some reason
or another but harmful because many scripts assume to find Perl
in /usr/bin/perl.
BUGS
If you find what you think is a bug, you might check the headers
of recently posted articles in the comp.lang.perl.misc
newsgroup. There may also be information at
http://www.perl.com/perl/, the Perl Home Page.
If you believe you have an unreported bug, please run the
perlbug program included with your release. Make sure you trim
your bug down to a tiny but sufficient test case. Your bug
report, along with the output of `perl -V', will be sent off to
<perlbug@perl.com> to be analysed by the Perl porting team.
SEE ALSO
The Changes file for exhaustive details on what changed.
The INSTALL file for how to build Perl.
The README file for general stuff.
The Artistic and Copying files for copyright information.
HISTORY
Written by Gurusamy Sarathy <gsar@umich.edu>, with many
contributions from The Perl Porters.
Send omissions or corrections to <perlbug@perl.com>.