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Module::Implementation provides an easy way to load the "best" of multiple implementations of the same function. Its documentation mostly revolves around the situation where you have an XS implementation and a pure Perl implementation, and wish to load the XS if posssible, but fall back to pure Perl. But it works just as well to switch between OS-specific implementations, or Perl-version-specific implementations.

That said, Perl does have conditional compilation. It's just not very pretty...

BEGIN { $^O eq 'Win32' ? eval q[ sub f { ... } ] # Win32 implementation : eval q[ sub f { ... } ] # Linux implementation };

Update: For longer pieces of code, heredocs look quite nice...

BEGIN { eval($^O eq 'Win32' ? <<'WIN32' : <<'LINUX') }; sub f { print "f-w\n" } sub g { print "g-w\n" } WIN32 sub f { print "f-l\n" } sub g { print "g-l\n" } LINUX

Update II: Also, bear in mind that constants used in conditionals are optimized away by the compiler, so:

use constant RUNNING_IN_HELL => ($^O eq 'Win32'); sub f { if (RUNNING_IN_HELL) { ...; } else { ...; } }

... the conditional should be optimized away at compile time, so you don't get the overhead of a string comparison operation every time the function gets called.

package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name

In reply to Re: Writing portable code by tobyink
in thread Writing portable code by rovf

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