On 07/01/2011 12:47 PM, Janko Mivšek wrote:
> S, Julian Fitzell piše:
>> 2011/6/30 Janko Mivšek <[email protected]
>>
>> Whole point is that this is a non-blocking code, in contrast to
>> continuation based approach like in Seaside, where similar code would
>> block and wait until dialog component returns answer.
>>
>> Janko, what are you talking about? If it's not blocking, it's just a
>> callback. Of course Seaside can do the same thing: you just use
>> #show:onAnswer:.
>
> Isn't the whole point of Seaside and continuations to enable worklow
> like in below example from the HPI Seaside tutorial? This code is
> blocking until the call: returns, isn't that so?
>
> From HPI tutorial [1], chapter 5-Forms, figure 5-2 :
>
> (self call: self taskEditor)
> ifTrue: [aTask copyFrom: self taskEditor task]
>
> Text bellow: "Even better, Seaside remembers the position in your code
> and runs it from there again, after the called component finished. This
> means, #call: blocks your current component, that is your callback
> evaluation, waits for the called component to be finished, and
> afterwards goes on with your callback. "
Yes, but continuations don't block a Process. All they do is allow you
to write code that is more readable. Instead of
self call: self taskEditor [ :value |
value ifTrue: [
aTask copyFrom: self taskEditor task ] ]
you can write
(self call: self taskEditor)
ifTrue: [aTask copyFrom: self taskEditor task]
There is no Process in the background waiting or anything.
In this simple case the benefit may not be that obvious but look at the
case with only two steps.
first := self askForFirstObject.
second := self askForSecondObject.
(first aSelector: second)
ifTrue: [ self something ]
ifFalse: [ self somethingElse ]
Sure you could write that in CSP but would you really want to?
Cheers
Philippe
