NAME

Exporter - module to control namespace manipulations

import - import functions into callers namespace

SYNOPSYS

package WhatEver; require Exporter; @ISA = (Exporter); @EXPORT = qw(func1, $foo, %tabs); @EXPORT_OK = qw(sin cos); ... use Whatever; use WhatEver 'sin';

DESCRIPTION

The Exporter module is used by well-behaved Perl modules to control what they will export into their user's namespace. The WhatEver module above has placed in its export list the function func1(), the scalar $foo, and the hash %tabs. When someone decides to use WhatEver, they get those identifier grafted onto their own namespace. That means the user of package whatever can use the function func1() instead of fully qualifying it as WhatEver::func1().

You should be careful of such namespace pollution. Of course, the user of the WhatEver module is free to use a require instead of a use, which will preserve the sanctity of their namespace.

In particular, you almost certainly shouldn't automatically export functions whose names are already used in the language. For this reason, the @EXPORT_OK list contains those function which may be selectively imported, as the sin() function was above. See Overriding builtin functions .

You can't import names that aren't in either the @EXPORT or the @EXPORT_OK list.

Remember that these two constructs are identical:

use WhatEver; BEGIN { require WhatEver; import Module; }

The import() function above is not predefined in the language. Rather, it's a method in the Exporter module. A sneaky library writer could conceivably have an import() method that behaved differently from the standard one, but that's not very friendly.