comment on

Here's another fun example...

use 5.010;
my $z = 0;

sub xxx () {
    $z = 1;
    return 2;
}

sub yyy () {
    my $zz = $z;
    $z = 0;
    return 2 + $zz;
}

if (xxx + yyy == yyy + xxx) {
    say "Addition is commutative";
}
else {
    say "The world has gone haywire!";
}
[download]

See addition; commutativity; etc.

Don't write functions with side-effects. And if you really must write functions with side-effects, be careful using them in expressions.

perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

In reply to Re^2: $1 not "freezing" in an addition by tobyink
in thread $1 not "freezing" in an addition by grondilu

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