Your code fails to import prototypes early enough (at compile time) to influence the proper parsing of the later code. For example, say a constant was defined in GD as: 
package GD;
sub BIGFONT () { 35 }

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Your code would cause this to be misparsed: 
my $result = BIGFONT + 3;

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because without the empty prototype, BIGFONT is a normal subroutine, and the +3 will be parsed as an argument to the subroutine. With the prototype, we get the proper behavior (and even compile-time constant folding). So, with compile-time importing, we get 38 for the answer, and without, we get 35.

So, to fix this, wrap my code in a BEGIN block, like so: 

my $have_GD = 0;
BEGIN {
  eval { require GD };
  unless ($@) {
    GD->import();
    $have_GD = 1;
  }
}

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Your code does OK without considering prototypes. You haven't been burned, but I'd add the word "yet" there.

-- Randal L. Schwartz, Perl hacker

update: Get rid of the "= 0" on the intialization. Sorry.

In reply to RE: RE: RE: RE: Checking to see if a particular Module is installed by merlyn
in thread Checking to see if a particular Module is installed by skazat

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