I think I would do it thusly: 
use strict;
use warnings;

eval {
 require Inline; Inline->import (C => Config =>
    BUILD_NOISY => 1);

 require Inline; Inline->import (C =><<' EOC');

 int foo() {
   warn("Using Inline\n");
   return 42;
 }

 EOC
};

# If Inline is unavailable, foo() simply calls
# the sub bar() pure perl implementation.
if($@) {
  *foo =\&bar; 
}

sub bar {
  warn("Using Pure Perl Implementation\n");
  return 42;
}

my $x = foo();
print "$x\n";

[download]
If Inline::C is not available, that uses the pure-perl implementation of foo() and outputs: 
Using Pure Perl Implementation
42

[download]
Otherwise, it uses the the Inline::C implementation of foo() and outputs: 
Using Inline
42

[download]
NOTE: Running that script with Inline support will also output the C compilation report - but only for the *first* running, of course.
Note also that those who have Inline::C can still access the pure-perl implementation of foo() if they wish, by directly calling bar().

Cheers,
Rob

In reply to Re: Best way to implement Inline::C/Pure Perl function in a module? by syphilis
in thread Best way to implement Inline::C/Pure Perl function in a module? by uG

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