Re^3: constants wont optimize

Actually, as you've found out, your way is the complicated one.

Simple:

use constant haveMod => eval { require mod; };
[download]

And for the non-trivial:

my $haveMod;
BEGIN {
   ...[ something complicated ]...
   $haveMod = ...;
}

use constant haveMod => $haveMod;
[download]

or even

BEGIN {
   ...[ something complicated ]...
   require constant;
   import constant haveMod => ...;
}
[download]

PS - require always returns true, so the "1" is redundant.

Comment on Re^3: constants wont optimize Select or Download Code

Replies are listed 'Best First'.
Re: [DUP] Re^3: constants wont optimize by patcat88 (Deacon) on Jul 10, 2011 at 20:58 UTC
I can't call "require". I am sniffing to see what PMs were loaded before the "use" that loads my PM. Its so my PM will integrate with other PMs loaded BEFORE my PM. Sort of like threads and threads::shared.	[reply]
Re^5: constants wont optimize by ikegami (Patriarch) on Jul 10, 2011 at 21:35 UTC
I can't call "require". You seem to have lost track of what you said because you're the one who used `require`. You said `use if eval { require mod; 1 }, qw' constant haveMod 1 ';` [download] is ugly because `constant` is being used. I pointed out that it's simply not true. Not only does that code not work, but it can be written as `use constant haveMod => eval { require mod; };` [download] I am sniffing to see what PMs were loaded before the "use" that loads my PM. Asked and answered. Or if you want to check for multiple modules, `use constant { map { no strict 'refs'; ( my $constant = $_ ) =~ s/:://g; "have$constant" => ${"${_}::VERSION"} } qw( Foo::Mod Bar::Mod ); };` [download]	[reply] [d/l] [select]