Simple logging with dynamic scoping
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sub log($msg) { &*log($msg); }
sub add-numbers($x, $y) {
log("Adding $x and $y");
$x + $y;
}
sub multiply-numbers($x, $y) {
log("Multiplying $x and $y");
$x * $y;
}
sub my-program($x, $y) {
say add-numbers($x, $y);
say multiply-numbers($x, $y);
}
sub MAIN() {
my &*log;
say "\n", 'No logging at all.';
&*log = -> $msg { };
my-program(1, 2);
say "\n", 'Log only additions (filtering).';
&*log = { .say if m/Adding/ };
my-program(1, 2);
say "\n", 'Log in all caps.';
&*log = { .uc.say };
my-program(1, 2);
say "\n", 'Log all messages.';
&*log = &say;
my-program(1, 2);
}
Raku
INFO