Attribute::Handlers::Prospective

Attribute::Handlers::Prospective is a Perl module that allows a package's class to define attribute handler subroutines for specific attributes. Once variables and subroutines are defined in that package, or in packages derived from that package, attributes with the same names as the attribute handler subroutines can be assigned. These assigned attributes will then be called in one of the compilation phases, namely BEGIN, CHECK, INIT, runtime, or END block.

The module's SYNOPSIS features various attribute handler subroutines such as Good, Bad, Ugly, Omni, AUTOATTR, PREATTR, and POSTATTR, each with its own unique functionality. The Good subroutine, for example, is invoked for any scalar variable with a :Good attribute, provided the variable was declared in MyClass or a derived class, or typed to MyClass. The subroutine can then be used to execute any desired action on $referent within the INIT phase.

AUTOATTR is particularly noteworthy since it is automagically invoked for any scalar, array, hash, or subroutine with an attribute for which no explicit handler is defined. This feature functions similarly to sub AUTOLOAD for method calls. Meanwhile, PREATTR and POSTATTR subroutines are automagically invoked before and after any other attribute handlers respectively.

Overall, Attribute::Handlers::Prospective provides a convenient and customizable solution for setting attribute handlers in Perl.