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Re: Why does changing a Moose attributes' properties remove the around modifierby stvn (Monsignor)
|on Jul 18, 2011 at 18:47 UTC||Need Help??|
Changing the properties of the base class' accessor removes the around modifier defined in the base class. When I simply inherit the base class without modifying it, however, the around modifier fires off properly.
Actually, it is not removing the 'around' modifier, you are simply creating a new accessor in your derived class, which itself is not around-ed. Allow me to explain ...
When you create an attribute, Moose compiles the accessor methods for you and installs them in the package in which they are defined. These accessor methods are nothing magical (in fact, nothing in Moose is very magical, complex yes, but magical no), and so they are inherited by subclasses just as any other method would be.
When you "around" a method (as you are doing here) Moose will extract the sub from the package, wrap it and replace the original with the wrapped version. This all happens in the local package only, the method modifiers do not know (or care) anything about inheritance.
When you change an attributes definition using the +attr form, Moose looks up the attribute meta-object in the superclass list and then clones that attribute meta-object, applying the changes you requested and then installs that attributes into the local class. The result is that all accessor methods are re-compiled into the local class, therefore overriding the ones defined in the superclass.