The "orthodox party line", as you call it, is the accumulated experiential knowledge of thousands of man-years. It encompasses every single phase of the code development cycle (which, by the way, is based on more of those thousands of man-years).

The complaints I have are from the phase I have the most experience in - maintenance. As a maintenance programmer, I am looking for the code to be as succinct, yet as informative as possible. The key here is that I'd prefer informative over succinct.

Why is that important? It reduces the time I am required to take in order to make the changes I'm told to do safely. The key there is "safely". A maintainer very often will not know the majority of the system. The more information the original developer gives me, the more confidence I have that I know what's going on.

What does all of that matter to the points I made?

  1. my $class = ref $class || $class; This, to me, says that this method can be used as either an instantiation method or a cloning method. (In other words, can be called either as Foo::new or $foo->new.)

    new(), by convention, is usually the instantiator. clone(), also by convention, is usually a cloner. new() is a class method, clone() an object method.

    They will both return you a new object, yes. But, the two methods are not the same internally. One creates a new object from values you give it (plus possibly some defaults) and the other creates an object from the object that clone() was called upon.

    This doesn't mean you can't have new() do both things. But, I've never seen a new() function that had the offending line and be a cloning method. If it doesn't do both things, you have a NO-OP that is potentially confusing to your maintainer.

    It's also confusing in that other developers using your class may treat the instantiation method as a cloning method. If that were to happen, that would make my head (as your maintainer) hurt really badly.

  2. Other responders have made the case for why Base classes shouldn't know about their children. I'll just say that dynamic loading of child classes is a maintenance nightmare.

Remember - maintenance programmers will never have the following:

And, just because your system isn't a large system doesn't mean you should code it poorly. Get the right habits now, when you can fix your mistakes. Don't get sloppy.

------
We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

In reply to Re3: Constructor/Factory Orthodoxy by dragonchild
in thread Constructor/Factory Orthodoxy by mojotoad

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