Same is different?

[BooK]

In CGI will be with you, always, I used the content of CGI.pm to extract all four letter bits from it. I took care of line endings using chomp. Still, on different platforms, with the same version of CGI.pm, I get different results.

Why is it that the same version of CGI.pm is different on different platforms? For further checking:

$CGI::VERSION	Perl -v	arch	OS Platform/version	MD5 hash
2.42	5.005_02	aix	AIX/4.2.1	be77c9224712d83138b6f6d020ce8101
2.46	5.005_03	i386-freebsd	FreeBSD/4.1.1-RELEASE	342fae436d4d6a746a20bbbc1f2fceae
2.46	5.005_03	i386-linux	Linux/2.2.19	342fae436d4d6a746a20bbbc1f2fceae
2.46	5.005_03	MSWin32-x86-object (ActiveState 522)	MS-Windows/4.10.1998,P	903d4ad8e2d17990437c999eef9490c3
2.49	5.005_02	i386-freebsd	FreeBSD/2.2.7-RELEASE	557ca05ecd1f419f54b91018974adcff
2.56	5.6.0	i386-linux	Linux Mandrake/2.2.14-15mdk	94ecf90cf567e9435a3db89ef50a72b7
2.56	5.6.0	i386-openbsd	OpenBSD/2.7	19c66694aa19632c51c8802782076cb5
2.74	5.6.0	MSWin32-x86-multi-thread (ActiveState 620)	MS-Windows/4.10.1998,P	355fc673032bedeb3cc0cb042738af22

Naturally, this calculus has problems, since line endings do vary between Win32 and Unix... But still, there are differences. Why?

Update: So I am stupid. tye suggested to use diff, which showed me the differences: some hardcoded globals, like $TempFile::TMPDIRECTORY do change between OSes...

Tool used: perl -p0777MDigest::MD5=md5_hex -e '$_=md5_hex$_'

[DrZaius]

Does this mean that CGI isn't always with you if you are trying to build a portable system?

This is complete theory, but merlyn suggested in a previous node that in the worst case you can include the contents of CGI in a BEGIN block.

If there are platform specific variables, this means you have to change your code for different platforms.

Same deal with use lib.

[BooK]

I think this mostly means I am a stupid wheening moron... :-S

In my obfuscated code, I assumed that the same version of CGI.pm would be identical (except for line-endings) on every platform Perl runs on. This is false. But the differences are in fact very tiny (a few lines), and mostly regard configuration parameters, which actually and naturally change between platforms and installs.

I think the Perl core (and CGI is part of the standard distribution) is you best bet at portable code. This doesn't include Obfuscation, that's all... :-)