Thanks viktor
we will fix that. There was a dicussion on removing deepCopy and cleaning the
copy mess :)
Stef
On Jan 20, 2010, at 1:44 AM, Viktor Kerkez wrote:
> Hi,
>
> Since this is my first post on the list, first I want to thank you all for
> the great job you're doing on Pharo :) It was a real revelation when I
> discovered it :)
>
> Now to the question:
>
> I'm reading the Pharo by Example, and came to this part:
>
> The problem with deepCopy is that it will not terminate when applied to a
> mutually recursive structure:
> a1 := { 'harry' }.
> a2 := { a1 }.
> a1 at: 1 put: a2.
> a1 deepCopy −! ... does not terminate!
>
> (Pharo actually get stuck at the step: a1 at: 1 put: a2. but that's not the
> question :) )
>
> 1. Isn't this behaviour (the complete environment get stuck and there is no
> way to unfreeze it) considered a bug? I mean the environment shouldn't let
> you shoot yourself in the foot (at least not so easily). Actually the same
> behaviour can be created just doing: [true] whileTrue: []...
>
> 2. Shouldn't Pharo recognize recursive structures in some way?
>
>
> I'm asking because I'm coming from a Python world, which is very similar to
> smalltalk in some manners and I'm trying to make a big picture comparison in
> my head.
>
> 1. I know that this doesn't really compares to Pharo which is a graphical
> environment, but in python you can always hit Ctrl-C and break the statements
> that block...
>
> >>> while True:
> ... pass
> ...
> ^CTraceback (most recent call last):
> File "<stdin>", line 1, in <module>
> KeyboardInterrupt
> >>>
>
> Shouldn't the UI thread always be responsive?
>
> 2. And Python recognizes recursive structures:
>
> >>> a = []
> >>> a
> []
> >>> a.append(5
> ...
> KeyboardInterrupt
> >>> a = []
> >>> a
> []
> >>> a.append(5)
> >>> a
> [5]
> >>> a.append(a)
> >>> a
> [5, [...]]
> >>> a[0]
> 5
> >>> a[1]
> [5, [...]]
> >>> a[1][1][1][1][0]
> 5
> >>>
>
>
> Don't get me wrong, I'm not trying to start a language war :) I wouldn't got
> to page 171 if I'm not really interested in Smalltalk :-D I'm just trying to
> get a clearer vision if these are some things that are there for some reason
> (design decision), or they are just not yet implemented, or they cannot be
> implemented for some other reasons?
>
> Thank you in advance for your time :),
> Viktor
>
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