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in reply to Re^3: Mutator chaining considered harmful
in thread Mutator chaining considered harmful

Your entire post is predicated on a simple straw man argument. You claim that Aristotle is against method chaining because he isn't "used to" it. Frankly, I think that's condescending and silly, but it's also wrong. The argument isn't that it's hard to "get used to," but that even if you are intimately familiar with it, it's hard to understand code that uses it. Take this code example:

$foo->bar(2)->baz(3)->qux;

Versus this one:

my $bar = $foo->bar(2); $bar->baz(3); $bar->qux;

The first requires a lot more effort to decipher than the 2nd. If you're not familiar with the methods and their return values in the 1st snippet, you'd have to look them up in the documentation. Even if you knew the method return values off the top of your head, you'd have to trace the chain carefully to make sure you understand what's going on.

In the 2nd, if you didn't know the return values, you could take a reasonable guess, and probably be right. And if you did know the return values, then it's obvious what's going on without any thought required at all. This is called self documenting code, and it's generally something we strive for.

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Re^5: Mutator chaining considered harmful
by eric256 (Parson) on Dec 30, 2004 at 19:44 UTC

    You missed one giant and important point. If you are familar with the style then its not more difficult to decipher.

    $foo->bar(2) ->baz(3) ->qux;

    Is no more difficult to read than:

    my $bar = $foo->bar(2); $bar->baz(3); $bar->qux;

    My point all along has been that it is only hard to read if you aren't used to the style. Map, grep and sort used to be nearly impossible for me to read because that wasn't a style I had encountered before. Now I understand and recognize those patterns. If I know that the mutators return the object in order to allow chaining then that code is easy to follow. If I don't know that then a quick check to the POD makes it clear in an instant.

    The first requires a lot more effort to decipher than the 2nd.

    That is only true for those who arn't used to it, or don't use it. It is not true for everyone, it is not an absolute that one is harder or easier to read. Like I said originaly, method chaining (mutators or otherwise) has always made perfect sense to me, maybe it's the way I think or experiences I've had. Either way, arguments that it's bad because it's hard to decipher, read, trace, etc, are all false because it is just a matter of the readers perception/experience.

    Frankly, I' amused you think that's condescending because I think it's condescending to assume that because some people can't read it that it should be considered harmfull by everyone.


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    Eric Hodges
      You missed one giant and important point. If you are familar with the style then its not more difficult to decipher.

      It is more difficult to decipher, because it's ambiguous. The ambiguity must be resolved somehow. In the first example, you have to follow the chain of methods and know what type of thing they return. In the 2nd example, the variable name and usage is a big clue that helps resolve the ambiguity.

      My point all along has been that it is only hard to read if you aren't used to the style.

      It's not more difficult to read, it's more difficult to understand.

      Frankly, I' amused you think that's condescending

      I say your view is condescending, because rather than accept the fact that someone understands a concept that they don't like, you instead decided they must not understand it fully.

      Understanding how method chaining works is easy. Reading code that uses method chaining is not any more difficult than other types of operator or function chaining. The difficulty comes in when you don't know whether a method is returning the object it's working on, or a sub object.

        The difficulty comes in when you don't know whether a method is returning the object it's working on, or a sub object.

        Finaly an objection that I can understand and agree on. Thank you for at least pointing that out to me. If it was implied in the other parts of this discussion then I somehow missed that.


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        Eric Hodges
        If you don't know what a method is returning, it doesn't help to store all those intermediate values in variables or throw them away or whatever. Whatever style you use, you need to read the documentation.

        The only valid argument I can see against method chaining (and this applies to all method chaining, not just mutator chaining) is that intermediate failures are hard to catch.

        The difficulty comes in when you don't know whether a method is returning the object it's working on, or a sub object.

        So, basically you are saying you don't think the method names are picked appropriately? Perhaps you'd prefer Hungarian notation for methods?