Mac-Source 1994 July/Mac-Source_July_1994.iso/HyperCard/USING APPS AS XCMDs/README

Text File | 1990-06-30 | 2KB | 35 lines

XXCMD (eXternal XCMD) is an XCMD which helps to overcome the limitations
of normal XCMDs.  Normal XCMDs cannot have global data and must be less
than 32K bytes long.  XXCMD gets around these limitations by acting as
an interface between HyperCard and specially written applications.
Instead of being launched by the Mac OS, the new XXCMDs are loaded into
HyperCards environment and given their own "a5 world".

The file xxcmd_shell.c takes care of most of the difficulties of
interfacing with HyperCard.  Most applications will just have to write
the two routines xxcmd_init() and xxcmd_dispatch() and then link with
xxcmd_shell.c.o.  xxcmd_init() is called only once when the XXCMD is
first loaded.  xxcmd_dispatch() is the routine that should do the real
processing.

There is no documentation at this point.  The best source of information
is the source code.  Please try to read it.  If you have questions you
can send me e-mail.  As I respond to more and more questions I will try
to collect the answers into a more structured document.  This code is
not yet meant to be used by the masses, only the few who absolutely need
to get around one of HyperCard's limitations.

The first thing to remember is that a5 != CurrentA5, so routines that
depend on a5 (mostly QuickDraw and HyperCard Callbacks) will not work
(unless you setup a5 correctly).  xxcmd_shell.c takes care of setting
the current directory to the directory of the current stack, so stdio
will read and write files from/to this directory.


Brad Pickering
[e-mail]

requires:
> HyperCard 1.1
>= enough memory to hold HyperCard + any XXCMD you call.
>= MPW 3.0