Re: Parameters, subs and the shift function

[Abigail-II]

Parameters to a function get flattened to a single list. If you call a sub as test (3, @a, @b), then inside test you can't distinguish what came from @a and what from @b. If you want to pass entire arrays, you will have to pass references, and deal with references in the function.

    sub test {
        my $number = shift;
        my @array1 = @{+shift};  # Shift off the reference, and derefe
+rence it
        my @array2 = @{+shift};
        # Do your stuff
    }
    test (2, \@a, \@b);

Abigail

[monktim]

Abagail-II, what is the signifigance of the + in the shift statements? Why is this a good thing to do?

my @array1 = @{+shift};
my @array2 = @{+shift};

Thanks,
Tim

[Abigail-II]

Run it under strict, and try it without the +. The error message you get will enlighten you.

Abigail

[monktim]

Ahh, thank you. I'm a little embarrassed. I never dereferenced a builtin like shift only user defined functions.

Global symbol "@shift" requires explicit package name at noname5.pl li
+ne 5.
Global symbol "@shift" requires explicit package name at noname5.pl li
+ne 6.
Execution of noname5.pl aborted due to compilation errors.