- KNOWN ISSUES
- SEE ALSO
- COPYRIGHT AND LICENSE
MooX::Const - Syntactic sugar for constant and write-once Moo attributes
use Moo; use MooX::Const; use Types::Standard -types; has thing => ( is => 'const', isa => ArrayRef[HashRef], );
use Types::Const -types; has thing => ( is => 'ro', isa => Const[ArrayRef[HashRef]], coerce => 1, );
It modifies the
has function to support "const" attributes. These are read-only ("ro") attributes for references, where the underlying data structure has been set as read-only.
This will return an error if there is no "isa", the "isa" is not a Type::Tiny type, if it is not a reference, or if it is blessed object.
Simple value types such as
Str are silently converted to read-only attributes.
As of v0.5.0, it also supports write-once ("once") attributes for references:
has setting => ( is => 'once', isa => HashRef, );
This allows you to set the attribute once. The value is coerced into a constant, and cannot be changed again.
Note that "wo" is a deprecated synonym for "once". It will be removed in the future, since "wo" is used for "write-only" in some Moose-like extensions.
As of v0.4.0, this now supports the
has thing => ( is => 'const', isa => ArrayRef[HashRef], strict => 0, );
When this is set to a false value, then the read-only constraint will only be applied when running in strict mode, see Devel::StrictMode.
strict is assumed to be true.
Accessing non-existent keys for hash references will throw an error. This is a feature, not a bug, of read-only hash references, and it can be used to catch mistakes in code that refer to non-existent keys.
Unfortunately, this behaviour is not replicated with array references.
See Types::Const for other known issues related to the
This module appears to work with Moose, and there is now a small test suite.
It does not work with Mouse. Pull requests are welcome.
Class::Accessor antlers/moose-like mode uses "wo" for write-only attributes, not write-once attributes.
As of v0.5.0, you should be using "once" instead of "wo".
Please report any bugs or feature requests on the bugtracker website https://github.com/robrwo/MooX-Const/issues
When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.
Robert Rothenberg <firstname.lastname@example.org>
This module was inspired by suggestions from Kang-min Liu 劉康民 <email@example.com> in a blog post.
Kang-min Liu 劉康民 <firstname.lastname@example.org>
This software is Copyright (c) 2018-2020 by Robert Rothenberg.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)