---
name: "HTML::Widget::Constraint::CallbackOnce"
section: "3pm"
platform: "linux"
package: "libhtml-widget-perl"
version: "1.11-7"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/HTML::Widget::Constraint::CallbackOnce"
---

# HTML::Widget::Constraint::CallbackOnce(3pm)

CallbackOnce Constraint

## NAME

HTML::Widget::Constraint::CallbackOnce - CallbackOnce Constraint

## SYNOPSIS

```
    my $c = $widget->constraint( 'CallbackOnce', 'foo', 'bar' )->callback(
      sub {
        my ($foo, $bar) = @_;
        return 1 if $foo == $bar * 2;
    });
```

## DESCRIPTION

A callback constraint which will only be run once for each call of  "process" in HTML::Widget.

## METHODS

### callback

### cb

Arguments: \\&callback

Requires a subroutine reference used for validation, which will be passed  a list of values corresponding to the constraint names.

"cb" is provided as an alias to "callback".

### process

Overrides "process" in HTML::Widget::Constraint to ensure "validate" is  only called once for each call of "validate".

### render\_errors

Arguments: `@names`

A list of element names for which an error should be displayed.

If this is not set, the default behaviour is for the error to be displayed  for all of the Constraint's named elements.

### validate

perform the actual validation.

## AUTHOR

Carl Franks `"cfranks@cpan.org"`

## LICENSE

This library is free software, you can redistribute it and/or modify it under the same terms as Perl itself.