July 2018 Archives

Exploring Type::Tiny Part 1: Using Type::Params for Validating Function Parameters

Type::Tiny is probably best known as a way of having Moose-like type constraints in Moo, but it can be used for so much more. This is the first in a series of posts showing other things you can use Type::Tiny for.

Let's imagine you have a function which takes three parameters, a colour, a string of text, and a filehandle. Something like this:

  sub htmlprint {
    my %arg = @_;
      '<span style="color:%s">%s</span>',

Nice little function. Simple enough. But if people call it like this:

  htmlprint( file => $fh, text => "Hello world", color => "red" );

... then they'll get weird and unexpected behaviour. Have you spotted the mistake?

About Toby Inkster

user-pic I'm tobyink on CPAN, IRC and PerlMonks.