Re: using constants to trigger debug code

[liz]

To further what the other monks already said.

When using constants with debugging, I'm usually using an environment variable to signal the level of debugging info required, with variations on the following code:

BEGIN {
    my $level = $ENV{'FOO_DEBUG'} || 0;
    eval "*Foo::DEBUG = sub () {$1}" if $level =~ m#^(\d+)$#s;
} #BEGIN

if (Foo::DEBUG) {
    print "We're debugging\n";
}

If this code is run with -MO=Deparse, you get:

sub BEGIN {
    my $level = $ENV{'FOO_DEBUG'} || 0;
    eval "*Foo::DEBUG = sub () {$1}" if $level =~ /^(\d+)$/s;
}
'???';

If you set the environment variable FOO_DEBUG to 1, you get:

sub BEGIN {
    my $level = $ENV{'FOO_DEBUG'} || 0;
    eval "*Foo::DEBUG = sub () {$1}" if $level =~ /^(\d+)$/s;
}
do {
    print "We're debugging\n"
};

Hope this helps.

Liz

[adrianh]

See Poor man's logging for a variant of the same sort of idiom.