---
name: "Tie::Hash::Regex"
section: "3pm"
platform: "linux"
package: "libtie-hash-regex-perl"
version: "1.14-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Tie::Hash::Regex"
---

# Tie::Hash::Regex(3pm)

Match hash keys using Regular Expressions

## NAME

Tie::Hash::Regex - Match hash keys using Regular Expressions

## SYNOPSIS

```
  use Tie::Hash::Regex;
  my %h;
  tie %h, 'Tie::Hash::Regex';
  $h{key}   = 'value';
  $h{key2}  = 'another value';
  $h{stuff} = 'something else';
  print $h{key};  # prints 'value'
  print $h{2};    # prints 'another value'
  print $h{'^s'}; # prints 'something else'
  print tied(%h)->FETCH('k'); # prints 'value' and 'another value'
  delete $h{k};   # deletes $h{key} and $h{key2};
```

or (new! improved!)

```
  my %h : Regex;
```

## DESCRIPTION

Someone asked on Perlmonks if a hash could do fuzzy matches on keys - this is the result.

If there's no exact match on the key that you pass to the hash, then the key is treated as a regex and the first matching key is returned. You can force it to leap straight into the regex checking by passing a qr'ed regex into the hash like this:

```
  my $val = $h{qr/key/};
```

`"exists"` and `"delete"` also do regex matching. In the case of `"delete"` *all* values matching your regex key will be deleted from the hash.

One slightly strange thing. Obviously if you give a hash a regex key, then it's possible that more than one key will match (consider `$h{qw/./}`). It might be nice to be able to do stuff like:

```
  my @vals = $h{$pat};
```

to get *all* matching values back. Unfortuately, Perl knows that a given hash key can only ever return one value and so forces scalar context on the `"FETCH"` call when using the tied interface. You can get round this using the slightly less readable:

```
  my @vals = tied(%h)->FETCH($pat);
```

### ATTRIBUTE INTERFACE

From version 0.06, you can use attributes to define your hash as being tied to Tie::Hash::Regex. You'll need to install the module Attribute::Handlers. Simply declare your hash using the attribute syntax:

```
    my %hash :Regex;
```

## METHODS

### FETCH

Get a value from the hash. If there isn't an exact match try a regex match.

### EXISTS

See if a key exists in the hash. If there isn't an exact match try a regex match.

### DELETE

Delete a key from the hash. If there isn't an exact match try a regex match.

## AUTHOR

Dave Cross \<dave@mag-sol.com\>

Thanks to the Perlmonks \<http://www.perlmonks.org\> for the original idea and to Jeff "japhy" Pinyan for some useful code suggestions.

## COPYRIGHT

Copyright (C) 2001-8, Magnum Solutions Ltd.  All Rights Reserved.

## LICENSE

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

## SEE ALSO

[**perl**(1)](/perl/1.md).

[**perltie**(1)](/perltie/1.md).

**Tie::RegexpHash**(1)