Beefy Boxes and Bandwidth Generously Provided by pair Networks
XP is just a number

Re^5: What is true and false in Perl?

by jdporter (Canon)
on Oct 18, 2012 at 15:25 UTC ( #999756=note: print w/replies, xml ) Need Help??

in reply to Re^4: What is true and false in Perl?
in thread What is true and false in Perl?

The same thing tobyink and tye said, though more obtusely and snarkily.

Here's another example:

tie my $var, 'Some::BlackBox::Module'; $var = "45"; if ( $var ) { print "var is true\n" } # doesn't print! WTF?

The mere fact that an expression evaluates to a true value in scalar context doesn't mean it is true.

tie and overload are among the user-accessible features which can muddy the true/false waters.

An example like this should make the principle more obvious:

my $obj = ObjectWithLotsOfOpaqueStructure::AndLotsOfHiddenState->new( -use_overloading => 1, ); if ( $obj ) { print "obj is 'true'.\n"; # What does this even mean? # Maybe obj is an iterator with another available item? }

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://999756]
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others meditating upon the Monastery: (11)
As of 2016-10-28 09:51 GMT
Find Nodes?
    Voting Booth?
    How many different varieties (color, size, etc) of socks do you have in your sock drawer?

    Results (379 votes). Check out past polls.