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Re^3: Code Maintainability

by autarch (Hermit)
on Dec 06, 2008 at 16:32 UTC ( #728565=note: print w/replies, xml ) Need Help??

in reply to Re^2: Code Maintainability
in thread Code Maintainability

Actually, I think it's more than just cryptic vs verbose. One of those examples has a serious logical flaw, and the other doesn't.

my $circle = Circle->new(); # What is $circle now?! $circle->set_radius(4.5); # or now? $circle->set_origin(2.3, 2.2); $circle->set_visibility(1);

See those comment I added? When you first create a circle object without any parameters, what is it, logically speaking? It has no radius and no origin, so it's more like a theoretical circle, but not representative of any real-world circle.

After we set a radius, it starts to make sense, though maybe in our particular app circles always need an origin too.

This dovetails with one of my newer mantras, which is that mutable state is evil. In the "pass everything to the constructor" version, we might be able to avoid (or at least limit) our mutators. If we're lucky, there's no need to change the radius of a circle, we can just make new ones with different radii. Avoiding mutable state greatly simplifies code. It makes APIs smaller, and makes reasoning about an application much simpler.

Java, with it's regular pattern of "construct, set, and call", makes mutable state a given, and that's a terrible thing to do.

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