Re: Understanding use and require fully

in reply to Understanding use and require fully

use Module LIST is equivalent to:

BEGIN { require Module; import Module LIST; }
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So one _big_ difference is that use is executed at _compile_ time, whereas require is only executed at "run" time.

Generally I would always use use even if you don't export any symbols.

One place where require would be preferred over use is when you want to include a module only when it really is needed. So you'll see code like:

if ($type eq "Excel file") {
  require SpreadsheetReader::Excel;
  my $parser = SpreadsheetReader::Excel->new();
  ...
}
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Re^2: Understanding use and require fully by chromatic (Archbishop) on Aug 01, 2008 at 17:44 UTC
use Module LIST is equivalent to: `BEGIN { require Module; import Module LIST; }` Nit: it's actually equivalent to: `BEGIN { require Module; Module->import( LIST ); }` use always performs a method call, where the indirect invocation form you had sometimes does not perform a method call. (If you want to be very specific, it's probably closer to `Module::->import( LIST )`, but you have to read the code to `Perl_utilize()` in C to make sure of that.)	[reply] [d/l] [select]

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Re^2: Understanding use and require fully
by chromatic (Archbishop) on Aug 01, 2008 at 17:44 UTC

use Module LIST is equivalent to: BEGIN { require Module; import Module LIST; }

Nit: it's actually equivalent to:

BEGIN { require Module; Module->import( LIST ); }

use always performs a method call, where the indirect invocation form you had sometimes does not perform a method call. (If you want to be very specific, it's probably closer to Module::->import( LIST ), but you have to read the code to Perl_utilize() in C to make sure of that.)

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