[Pharo-project] Case of caseOf

Igor Stasenko siguctua at gmail.com
Mon Sep 22 13:03:31 EDT 2008


2008/9/22 Stefan Schmiedl <s at xss.de>:
> On Mon, 22 Sep 2008 17:25:16 +0300
> "Igor Stasenko" <siguctua at gmail.com> wrote:
>
>> I see no real usage of #caseOf: or #caseOf:otherwise: in Pharo - just
>> in single place (ProcessBrowser).
>> However, i see a multiple places in Croquet image where it is used in a form of:
>>
>> cmd := data at: 1.
>> cases := { .... }.
>> cmd caseOf: cases.
>>
>>
>> Which also proves that it not worth using it, because it can be simply
>> replaced by single line:
>
> Yes, it *can* be replaced, but *should* it be replaced?
> The three lines above are way more readable than the one line below.
>

You forgot, that there is more than just three lines , because between
curly braces you'll have something like:

caseA -> [ self dosomethingWithData ].
caseB -> [ self dosomethingElseWithData ].
...

It is completely different from smalltalk style, where we have many
methods but containing few lines of code.

and i doubt that such 'not-so-three' lines are more readable than line
, presented by me :)

>> self perform: (cmdSelectors at: (data at:1) ) withPossibleArguments:
>> (Array with: data).
>
> How about going after the creator of the data array first? It seems to
> be a primitive data structure wanting to become a MessageSend or
> something similar.

it is used  in places where code encoding/decoding data packets (my
guess), and its first byte indicating a packet type, or something like
that.
I suspecting that this code was ported to smalltalk from C, and
'caseOf:' used simply because it is easier to port things blindly, in
same manner as it was written in original, than doing hard work
rewriting code to accommodate in new language/environment.
Of course, i can't blame people doing this. Sometimes we need results
fast. And when things done & working, we need something else to do
(fast as well) :)

>
> Just making smalltalk,
> s.
>
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-- 
Best regards,
Igor Stasenko AKA sig.




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