Programming Perl, 4th Edition

wantarray

wantarray

This function returns true if the context of the currently executing subroutine is looking for a list value, and false otherwise. The function returns a defined false value ("") if the calling context is looking for a scalar, and the undefined false value (undef) if the calling context isn’t looking for anything; that is, if it’s in void context.

Here are examples of typical usage:

return unless defined wantarray;    # don't bother doing more
my @a = complex_calculation();
return wantarray ? @a : \@a;

See also caller. This function should really have been named “wantlist”, but we named it back when list contexts were still called array contexts.