This is the "correct" way to do this as use is a compile-time directive (is that the right term?). Perl will see the use inside the BEGIN { } or the eval { } and go search for that module.

Addmittedly, it is seems odd that 

BEGIN {
  if ($condition) {
    use Foo;
  }
}

[download]
does not do what you expect; but it makes more sense if you think of what it really does. Convert the above code into 
BEGIN {
  if ($condition) {
    BEGIN {
      require Foo;
      Foo::import();
    }
  }
}

[download]

Then remember that if you have this: 

print Bar::new();
print Bar::old();

package Bar;

sub new {
  sub old {
    return "I'm old";
  }
  return "I'm new";
}

1;

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you have created a real subroutine called "old" in package Bar that can be called. The same is true with the use inside the BEGIN { }; you created a real BEGIN { } block that will be executed at compile time in the order in which it was encountered. You will actually execute that code regardless of the if { } block that surrounds it.

Ivan Heffner
Sr. Software Engineer, DAS Lead
WhitePages.com, Inc.

In reply to Re^2: use depending on environment by Codon
in thread use depending on environment by Andre_br

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