perl file extenson question

perlfan99 has asked for the wisdom of the Perl Monks concerning the following question:

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Re: perl file extenson question by toolic (Bishop) on Jul 20, 2008 at 03:41 UTC
According to Perl Modules in perlmod: All Perl module files have the extension .pm. The use operator assumes this so you don't have to spell out "Module.pm" in quotes. This is at least one subtle difference.	[reply]
Re^2: perl file extenson question by perlfan99 (Sexton) on Jul 20, 2008 at 04:23 UTC
that make sense. thanks!	[reply]
Re: perl file extenson question by McDarren (Abbot) on Jul 20, 2008 at 03:11 UTC
Yes, correct. It's just a convention. .pm for modules, .pl for Perl programs/scripts. Both are just text files, and the perl interpreter (afaik) doesn't care about file extensions, so you can name them pretty much anything you like. Keeping with convention is usually a good idea, though :)	[reply]
Re: perl file extenson question by oko1 (Deacon) on Jul 20, 2008 at 15:38 UTC
Well, no - in fact, everything won't still work. ben@Tyr:/tmp$ echo -e 'sub greet { "Hello, world!\\n" }\n1;' > hello.p +l ben@Tyr:/tmp$ perl -Mhello.pl -we'print greet' syntax error at -e line 0, near "use hello." Execution of -e aborted due to compilation errors. ben@Tyr:/tmp$ perl -Mhello -we'print greet' Can't locate hello.pm in @INC (@INC contains: /etc/perl /usr/local/lib +/perl/5.8.8 /usr/local/share/perl/5.8.8 /usr/lib/perl5 /usr/share/per +l5 /usr/lib/perl/5.8 /usr/share/perl/5.8 /usr/local/lib/site_perl /us +r/local/lib/perl/5.8.7 /usr/local/share/perl/5.8.7 .). BEGIN failed--compilation aborted. [download] As toolic pointed out, you can't load a '.pl' file as a module; you'd have to use "require" (or "do") instead of "use". Which opens up a very large can of worms. Libraries are loaded at run-time; modules are loaded at compile time. This, in itself, is a huge difference that allows modules much, much more scope for action than libraries. "use Xyz" also imports the symbols and the semantics from package "Xyz" into the current one - not something that happens with "require Xyz.pl" (which just checks to see if Xyz.pl has already been loaded, updates %INC, and "wraps" a lexical scope block around the content of "Xyz.pl".) Last of all, libraries are pretty much deprecated. They're a Bad Idea - at least, they've come to be seen as one - for a number of reasons (namespace conflicts, among other reasons.) In general, the preferred thing is to "use" a module - and to create modules instead of libraries if you're building things. For more info, please see 'perldoc perlmodlib'. -- Human history becomes more and more a race between education and catastrophe. -- HG Wells	[reply] [d/l]