Params::Validate, how to require one of two parameters? - perl

Question

If I have a method that takes either one or the other of two named parameters, exactly one of which must be present, is there a way to handle that with Params::Validate?
$store->put( content_ref => $stringref );
or
$store->put( path => $path_to_file );
I'm not seeing it in the docs, but it seems like an obvious use case, so I thought I should ask.

Answer 1

You can use callbacks to achieve something along those lines:
#!/usr/bin/env perl
use strict;
use warnings;
package My::Class;
use Params::Validate;
use YAML;
sub new { bless {} => shift }
sub _xor_param {
my $param = shift;
return sub { defined($_[0]) and not defined($_[1]->{$param}) }
}
my %validation_spec = (
content_ref => {
'default' => undef,
callbacks => {
"Provided only if no 'path' is given"
=> _xor_param('path')
},
},
path => {
'default' => undef,
callbacks => {
"Provided only if no 'content_ref' is given"
=> _xor_param('content_ref')
},
},
);
sub put {
my $self = shift;
validate(#_, \%validation_spec);
print Dump \#_;
}
package main;
my $x = My::Class->new;
$x->put(path => 'some path');
$x->put(content_ref => \'some content');
$x->put(path => 'another_path', content_ref => \'some other content');
Output:
---
- path
- some path
---
- content_ref
- !!perl/ref
=: some content
The 'content_ref' parameter ("SCALAR(0xab83cc)") to My::Class::put did not pass
the 'Provided only if no 'path' is given' callback
at C:\temp\v.pl line 37
My::Class::put(undef, 'path', 'another_path', 'content_ref',
'SCALAR(0xab83cc)') called at C:\temp\v.pl line 47