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Re^3: Global symbol requires explicit package name

by greengaroo (Hermit)
on Nov 28, 2012 at 16:01 UTC ( #1006060=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Global symbol requires explicit package name
in thread Global symbol requires explicit package name

Exactly! If you know you will pass a large structure to a subroutine, better pass it as a reference! Like this:

# Calling routine routine ( $v1, $v2, \@array ); sub routine { my ( $fh, $h, $keys ) = @_; ... # Dereference the array in a loop: foreach my $key ( @{$keys} ) {

Testing never proves the absence of faults, it only shows their presence.


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Re^4: Global symbol requires explicit package name
by ColonelPanic (Friar) on Nov 28, 2012 at 16:43 UTC
    Yeah, but if you are only passing a couple of scalars, along with a single array (as in the original sub design), then passing by reference is not necessarily superior. It depends on what you are doing. Not passing by reference allows for more flexible calls to the sub:
    scalar_and_array_sub($foo, $bar, @values[1..5]); scalar_and_array_sub($foo, $bar, $value1, $value2, $value3); scalar_and_array_sub($foo, $bar, split(/\s/, $string));

    With pass by reference, these would have messier syntax.



    When's the last time you used duct tape on a duct? --Larry Wall

      Yes, but you can still use an ArrayRef, with the square brackets:

      scalar_and_array_sub($foo, $bar, [@values[1..5]]); scalar_and_array_sub($foo, $bar, [$value1, $value2, $value3]); scalar_and_array_sub($foo, $bar, [split(/\s/, $string)]);
      But I agree with you, if you don't pass too many arguments, you should use an Array instead of an ArrayRef.

      Testing never proves the absence of faults, it only shows their presence.
        The first example doesn't provide equivalent functionality, however. When an array slice is passed normally, modifying @_ will modify the original array. But this makes an anonymous copy of the array slice, which is discarded after the function call.


        When's the last time you used duct tape on a duct? --Larry Wall

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