Referencing class data in an object method directly makes it hard to cleanly override the object method in a sub-class. How would you write an overridden wear_out_sole()? You'd have to access $num_holey, but can't because it's in a separate package scope. You solved this already in your class with incr_num_holey(), which is what the Fine Manual is trying to suggest.

All that aside, I think you'll find that it's pretty unusual to use class data in a real OO system. In cases where you've really got some kind of class-wide data I'd rather see that data modeled as an object of its own and give each object that needs it a reference to the object. This is a common pattern for configuration data, for example, which is also a common (poor) use of class data.

Another example: I've created in-memory caches in some of my modules using class data. These days I'd use something like CHI instead and give each object a cache handle, defaulting to a memory caching driver that behaves like a class data hash.

-sam

In reply to Re: Still not getting it: hashref OO class variables by samtregar
in thread Still not getting it: hashref OO class variables by bramble

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