---
name: "Check::ISA"
section: "3pm"
platform: "linux"
package: "libcheck-isa-perl"
version: "0.09-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Check::ISA"
---

# Check::ISA(3pm)

DWIM, correct checking of an object's class.

## NAME

Check::ISA - DWIM, correct checking of an object's class.

## VERSION

Version 0.09

## SYNOPSIS

```
    use Check::ISA;
    if (obj($foo, "SomeClass")) {
        $foo->some_method;
    }
    # instead of one of these methods:
    UNIVERSAL::isa($foo, "SomeClass") # WRONG
    ref $obj eq "SomeClass"; # VERY WRONG
    $foo->isa("SomeClass") # May die
    local $@; eval { $foo->isa("SomeClass") } # too long
```

## DESCRIPTION

This module provides several functions to assist in testing whether a value is an object, and if so asking about its class.

## FUNCTIONS

- obj $thing, \[ $class \]

  This function tests if `$thing` is an object.

  If `$class` is provided, it also tests tests whether `"$thing->isa($class)"`.

  `$thing` is considered an object if it's blessed or a `"GLOB"` with a valid `"IO"` slot (the `"IO"` slot contains a FileHandle object which is the actual invocant). This corresponds directly to `"gv_fetchmethod"`.

- obj\_does $thing, \[ $class\_or\_role \]

  Just like `"obj"` but uses "DOES" in UNIVERSAL instead of "isa" in UNIVERSAL.

  "DOES" in UNIVERSAL is just like `"isa"` except it's use is encouraged to query about an interface, as opposed to the object structure. If `"DOES"` is not overridden by the ebject, calling it is semantically identical to calling `"isa"`.

  This is probably reccomended over `"obj"` for interoperability but can be slower on Perls before 5.10.

  Note that "DOES" in UNIVERSAL

- inv $thing, \[ $class\_or\_role \]

  Just like `"obj_does"`, but also returns true for classes.

  Note that this method is slower, but is supposed to return true for any value you can call methods on (class, object, filehandle, etc).

  Look into autobox if you would like to be able to call methods on all values.

- obj\_can $thing, $method

  - inv\_can $thing, $method

  Checks if `$thing` is an object or class, and calls `"can"` on `$thing` if appropriate.

## SEE ALSO

UNIVERSAL, Params::Util, autobox, Moose, asa

## REPOSITORY

\<https://github.com/manwar/Check-ISA\>

## BUGS

Please report any bugs or feature requests to `"bug-check-isa at rt.cpan.org"`,  or through the web interface at \<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Check-ISA\>. I will  be notified and then you'll automatically be notified of progress on your bug as I make changes.

## SUPPORT

You can find documentation for this module with the perldoc command.

```
    perldoc Check::ISA
```

You can also look for information at:

- •

  RT: CPAN's request tracker (report bugs here)

  \<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Check-ISA\>

- •

  AnnoCPAN: Annotated CPAN documentation

  \<http://annocpan.org/dist/Check-ISA\>

- •

  CPAN Ratings

  \<http://cpanratings.perl.org/d/Check-ISA\>

- •

  Search CPAN

  \<http://search.cpan.org/dist/Check-ISA/\>

## AUTHOR

Yuval Kogman \<nothingmuch@woobling.org\>

Currently maintained by Mohammad S Anwar (MANWAR), `"<mohammad.anwar at yahoo.com>"`

## LICENSE AND COPYRIGHT

Copyright (c) 2008 Yuval Kogman.

Copyright (c) 2016 Mohammad S Anwar.

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

Any  use,  modification, and distribution of the Standard or Modified Versions is governed  by  this License. By  using, modifying or distributing the Package, you accept this license. Do not use, modify, or distribute the Package, if you do not accept this license.

If your Modified Version has been derived from a Modified Version made by someone other than you,you are nevertheless required to ensure that your Modified Version\
  complies with the requirements of this license.

This  license  does  not grant you the right to use any trademark,  service mark, tradename, or logo of the Copyright Holder.

This license includes the non-exclusive, worldwide, free-of-charge patent license to make,  have made, use,  offer to sell, sell, import and otherwise transfer the Package with respect to any patent claims licensable by the Copyright Holder that are  necessarily  infringed  by  the  Package. If you institute patent litigation (including  a  cross-claim  or  counterclaim) against any party alleging that the Package constitutes direct or contributory patent infringement, then this License to you shall terminate on the date that such litigation is filed.

Disclaimer  of  Warranty:  THE  PACKAGE  IS  PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS  "AS IS'  AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES. THE IMPLIED WARRANTIES    OF   MERCHANTABILITY,   FITNESS   FOR   A   PARTICULAR  PURPOSE, OR NON-INFRINGEMENT ARE DISCLAIMED TO THE EXTENT PERMITTED BY YOUR LOCAL LAW. UNLESS REQUIRED BY LAW, NO COPYRIGHT HOLDER OR CONTRIBUTOR WILL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,  OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAY OUT OF THE USE OF THE PACKAGE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.