Re: When and where to use Visitor Pattern?

<Nicholls.Mark@xxxxxxxxx> wrote in message
news:1114618156.808945.16930@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

>
> if 'instanceof' is some form of reflection,

It's dynamic type checking, querying for the existence of interfaces, I
don't think you would call that reflection.

> then there are plenty of
> people (well at least me) who prefer the type safety of visitors....in
> fact in some sense I view visitors as typesafe reflection.
>
As typesafe casting, perhaps? Without the runtime cost of an instanceof or
typeof? I do agree with this characterization, I think it's correct.

But there's not really a material difference between the two approaches,
apart from matters of clarity. In both cases you have to enumerate all the
types of interest, and using instanceof/typeof is type safe.

> less clutter? I don't think that the visit method is particularly
> prohibitive in terms of clutter, though I accept that visitors can
> fracture your code into tiny itty bitty bits.
>
Yeah, I guess my main issue is that I find code written to the visitor
pattern to be less clear than code written in alternative styles, and I have
to confess to having a distaste for "tiny itty bitty bits".

Regards,
Daniel Parker


.

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