Re: Writing portable code

[tobyink]

in reply to Writing portable code

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.

[rovf]

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

This is great!!!! I did not consider combining several HERE documents, but after re-reading the section in perlop, I understand that for my particular application, this might indeed one way to go!