RE: Require / Use

Chris Devers <mailto:cdevers@xxxxxxxxx> wrote:

: : Ahem. It is most useful when I want to determine the module to load
: : dynamically, or when I want to load a module only if necessary to
: : save the time spent compiling it in the cases when it is not needed.
:
: :-)
:
: I think that counts as an esoteric-enough requirement that beginners
: can safely ignore the need for it unless & until they hit that wall.
:
: I'm assuming that most beginners won't be writing much or any code
: that needs to optimize loading a module multiple times...

Dynamic loading does not apply just to multiple loading of a single
module. It could also be used to check the existence of a module before
loading it.

An answer to the original question is incomplete without at least
a mention of the usefulness of 'require' under some intermediate to
advanced perl programming.


my $mail_module = load_mail_module();

warn q(No mail module) unless $mail_module;

sub load_mail_module {

eval { require mail_foo };
unless ( $@ ) {
mail_foo::import();
return 'mail_foo';
}

eval { require mail_bar };
unless ( $@ ) {
mail_bar::import();
return 'mail_bar';
}

eval { require mail_baz };
unless ( $@ ) {
mail_baz::import();
return 'mail_baz';
}

return;
}


... or to load modules only as needed.

print redirect( '/' );

sub user_data_form {

require Data::FormValidator;
Data::FormValidator::import();

# ...
}

sub redirect {
my $page = shift;

require CGI;
return CGI::redirect( $page );
}

__END__


HTH,

Charles K. Clarkson
--
Mobile Homes Specialist
254 968-8328






.

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