They do different things, so none is recommended over the other.

According to the manual, use is the equivalent of BEGIN { require Module; import Module LIST; } except that Module must be a bareword.

It really comes down to if you wish to import names into your current namespace, so that you would be able to type bar(), and not Foo::bar(). Your project will dictate which is better at the time.

Hope this helped,
-v.

Update: Kudos to friedo for reminding me in his post that there is also the matter of whether you want your code loaded at compile-time vs. runtime.

It really comes down to if you wish to import names into your current namespace

Well, no. It also comes down to whether you want code loaded at compile-time or runtime. And you can always manually call import if you require a module.

Thanks! Yeah, forgot about that one.

-v.
"Perl. There is no substitute."

I find that fully qualified calls to imported subs makes it easier to decipher the code at some later date. Otherwise the reader has to look up the sub in their head, or perldoc, when it could be right there where they need it most.

An alternative is to explicitely state all the imported functions in the use statement. For example, instead of saying

use Module;
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use

use Module qw( func1 func2 );
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This is a FAQ. Please see perlfaq8 for "What's the difference between require and use?"

Please also remember to use Super Search. Difference between 'use' and 'require' and Difference between 'use' and 'require' (two threads, same title) contain many helpful responses to this question.

See the perlfunc documentation for a discussion of the differences.

/J\

Please check use and require.

and others with require (require "Simple.pl").

Files with no package should be included using do, not require or use.

Erm... why?

It seems to me that the main difference between require and do is that do FILE will always load and execute the code, while require will only load it once:

From require:


... "require" demands that a library file be included if it hasn’t already been included. The file is included via the do-FILE mechanism, which is essentially just a variety of "eval". ...

"What should it profit a man, if he should win a flame war, yet lose his cool?"

Exactly. require will mysteriously fail if two modules need to use the file. It's a good habit to use do instead. You never know what someone will do in the future.

There's another reason. Using do over require conveys more information to the reader. Since modules must not be loaded using do, it's safe to assume something loaded using do is not a module. Using require wouldn't be as clear.

 
$shell> perl
use Module; # Not installed in your machine 

$shell> perl
require Module; # Not installed in your machine
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