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lib/Acme/constant.pm  view on Meta::CPAN

    use Acme::constant TIMESTAMP => localtime; # WRONG!

Usually, when this happens, it's possible to use C<scalar> operator in
order to force interpretation of code in scalar context.

    use Acme::constant TIMESTAMP => scalar localtime;

Constants return lists, not arrays (you don't use C<@> syntax, do
you?), so in order to get single element, you will need to put a
constant in parenthesis.

    use Acme::constant NUMBERS => 1..6;
    print join(" ", (NUMBERS)[2..4]), "\n";

=head2 Assignments

The assignments are done using standard C<=> operator.

    use Acme::constant SOMETHING => 1;
    SOMETHING = 2;

lib/Acme/constant.pm  view on Meta::CPAN

a list or array. As inconstant constant is neither a list or array,
the argument on right side is ran in scalar context. For example,
following code will only save 2, as comma operator is ran in scalar
context.

    use Acme::constant SOMETHING => 0;
    SOMETHING = (1, 2); # WRONG!
    print "Something is ", join(", ", SOMETHING), ".\n";

In order to force list interpretation, you need to put constant in
the parenthesis.

    use Acme::constant SOMETHING => 0;
    (SOMETHING) = (1, 2);
    print "Something is ", join(", ", SOMETHING), ".\n";

Similarly, you cannot modify list constant in scalar context, as Perl
expects you put a list, not a single value.

    use Acme::constant SOMETHING => (1, 2);
    SOMETHING = 3; # WRONG!
    print "Something is ", SOMETHING, ".\n";

To fix that, you need to put constant in parenthesis. This is only
needed when constant has different number of elements than one, so
after such assignment, you can use normal assignment, without
parenthesis.

    use Acme::constant SOMETHING => (1, 2);
    (SOMETHING) = 3;
    print "Something is ", SOMETHING, ".\n";
    SOMETHING = 4;
    print "Something is now ", SOMETHING, ".\n";

Also, the localization of Acme constants is broken, and while it will
change the value, it won't change value back after leaving the block.
This is related to that you cannot localize lexicals and references in