dynamic loading modules

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

Replies are listed 'Best First'.
Re: dynamic loading modules by daxim (Curate) on Sep 03, 2012 at 14:37 UTC
The symbol `GetOSName` is not defined at compile time, so move the conditional module loading into a BEGIN block.	[reply]
Re^2: dynamic loading modules by sdetweil (Sexton) on Sep 03, 2012 at 15:19 UTC
thx.. I added this to my begin block `if ($^O eq "MSWin32") { print ("begin\n"); my $win32 ="Win32.pm"; require $win32; import $win32 qw(GetOSName); }` [download] I get the print message fom my begin block code. and still call it `my $os = GetOSName();` [download] and it still fails Undefined subroutine &main::GetOSName	[reply] [d/l] [select]
Re^3: dynamic loading modules by chromatic (Archbishop) on Sep 03, 2012 at 18:07 UTC
This is never going to work: `my $win32 ="Win32.pm"; import $win32 qw(GetOSName);` [download] If there isn't already an `import()` in your current package, this will effectively become: `'Win32.pm'->import( 'GetOSName' );` Because there's no package called `Win32.pm`, nothing will get imported. You're better off writing: `Win32->import( 'GetOSName' );` ... or even: `'Win32'->import( 'GetOSName' );`	[reply] [d/l] [select]
Re^3: dynamic loading modules by choroba (Cardinal) on Sep 03, 2012 at 19:39 UTC
The line calling GetOSName() should never be called on any system other than Windows. Fix the logic of your program. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply]
Re: dynamic loading modules by choroba (Cardinal) on Sep 03, 2012 at 14:42 UTC
See if: `use if 'MSWin32' eq $^O, Win32; if ('MSWin32' eq $^O) { my $osname = MSWin::GetOSName(); }` [download] لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re^2: dynamic loading modules by sdetweil (Sexton) on Sep 03, 2012 at 15:23 UTC
I am already inside an If on the Os 'MSWin32', and do NOT have any 'use Win32' coded anywhere in my application. the code works fine, and requires these missing win32 modules when compiled on the unix platforms. I don't know what makes it work as is	[reply]
Re^3: dynamic loading modules by choroba (Cardinal) on Sep 03, 2012 at 15:41 UTC
`use if` is not an `if`. It moves the decision whether to use the module or not into the compilation phase (as BEGIN does). لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l] [select]
Re: dynamic loading modules by BrowserUk (Patriarch) on Sep 03, 2012 at 15:55 UTC
How about this? `>perl -MWin32 -wE"if(exists $::{'Win32::'} and exists $Win32::{'GetOSN +ame'} ) { say &{'Win32::GetOSName'}; }" WinVistaService Pack 1 >perl -wE"if(exists $::{'Win32::'} and exists $Win32::{'GetOSName'} ) +{ say &{'Win32::GetOSName'}; }" >` [download] With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. RIP Neil Armstrong	[reply] [d/l]
Re: dynamic loading modules by bulk88 (Priest) on Sep 03, 2012 at 21:02 UTC
Yall should know that the Win32:: subs are special. They are compiled into all Win32 perls, just like UNIVERSAL:: and version:: and are always around, see ext/Win32CORE/Win32CORE.pm in perl.git and ext/Win32CORE/Win32CORE.c in perl.git. But what is compiled into Perl is just a stub that does a require on Win32 for you.	[reply]
Re: dynamic loading modules by nikosv (Deacon) on Sep 03, 2012 at 15:23 UTC
it's much better to use Devel-CheckOS	[reply]
Re^2: dynamic loading modules by sdetweil (Sexton) on Sep 03, 2012 at 15:27 UTC
thanks.. I'll go look at this, but.. this is not the problem.. dynamically loading the module is my issue. this module will not install on an *ix based platform as it is windows only.. I have a workaround, but its manual, and someone else following after me will be stuck with my manual mode.	[reply]
Re^3: dynamic loading modules by nikosv (Deacon) on Sep 03, 2012 at 15:40 UTC
I see.what you are after can't happen.You can only save the user the trouble of trying to install your module in an incompatible OS by using Devel-CheckOS	[reply]
Re: dynamic loading modules by fishmonger (Chaplain) on Sep 03, 2012 at 15:36 UTC
Have you taken a look at using Module::Load::Conditional? http://search.cpan.org/~bingos/Module-Load-Conditional-0.54/lib/Module/Load/Conditional.pm	[reply]
Re^2: dynamic loading modules by sdetweil (Sexton) on Sep 03, 2012 at 15:44 UTC
sorry, thats again off the mark.. how do I code the source statement calling the function in the module AFTER I change from hard coded to dynamic loading? this part seems to be missing in any text I read.. my app today uses my $os = Win32::GetOSName(); there is NOT a 'use win32' anywhere.. I know, I coded it all. I don't know if there is some OTHER method loading this module. regardless.. coding explicitly Win32::GetOSName() gets me into trouble, so I ASSUME I have to change the code.. to WHAT? just my $os=GetOSName() fails. how is the compiler supposed to set this up for dynamic resolution vs static? thats what I'm asking for.	[reply]
Re^3: dynamic loading modules by fishmonger (Chaplain) on Sep 03, 2012 at 16:23 UTC
Unless I'm misunderstanding your goal, I don't see any reason why you can't use Module::Load or Module::Load::Conditional or a combination of both. Here's a simple test script which works for me. `#!/usr/bin/perl use strict; use warnings; use Module::Load; my $os = 'Yet Unknown'; if ( $^O =~ /MSWin/ ) { load 'Win32'; $os = Win32::GetOSName(); } print $os;` [download] Output of my test: D:\perl>test.pl Win7	[reply] [d/l]
Re^4: dynamic loading modules by sdetweil (Sexton) on Sep 03, 2012 at 16:58 UTC
Re^5: dynamic loading modules by Anonymous Monk on Sep 03, 2012 at 17:04 UTC
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