For the Visitor chapter it is in preparation... (first I should finish
the lecture schedule and after do another pass on the first book ) it
will be an extension of the Expression chapter
On Sat, Sep 16, 2017 at 1:53 PM, H. Hirzel <hannes.hir...@gmail.com> wrote:
> Stephane
>
> Thank you for the reminder in the chapter that classes are cheap!
> If I have a class hierarchy with 300 classes (for example builder
> classes) but they all implement just one method (#build) then that is
> not complex at all.
>
> Another thing:
>
> I assume you will have a chapter on visitors as well. Do you have an
> outline / draft for that?
>
> --Hannes
>
> On 9/11/17, Stephane Ducasse <stepharo.s...@gmail.com> wrote:
>> tx for the feedback!
>>
>>
>> On Mon, Sep 11, 2017 at 1:18 PM, H. Hirzel <hannes.hir...@gmail.com> wrote:
>>> Hello Stephane
>>>
>>> I like the emphasis of the chapter that implementing same selector
>>> several times at the proper place in a couple of classes is more
>>> important than to rely on inheritance.
>>>
>>> In particular the conclusion
>>>
>>> <citation>
>>> What is important to realise is that classes are cheap. It is better
>>> to write 5 little classes than a huge one. Some (even smart) people
>>> got confused by measuring complexity of a system using number of
>>> classes. Having many classes representing good abstractions with a
>>> single responsibility is much much better than having a single class
>>> exhibiting multiple responsibilities.
>>> </citation>
>>>
>>> Suggestion: put it into a 'Note' box.
>>>
>>>
>>>
>>>
>>>
>>> And replace
>>>
>>> 'got confused'
>>>
>>> with:
>>>
>>> 'get confused'
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Replace:
>>>
>>> Now the choices can be made over multiple tenth of classes.
>>>
>>> 'multiple tenth' is an uncommon expression
>>>
>>> Suggestion:
>>> Now the choices can be made over dozens of classes.
>>>
>>>
>>>
>>>
>>>
>>>
>>> However
>>> 'Sending a message is making a choice!'
>>> takes the view point of the mechanism which does the late binding.
>>>
>>> If I write
>>>
>>> aNode emitHTML: aStream
>>>
>>> I do not make the choice. There are different types of nodes and they
>>> all do the same in the sense that they produce HTML code.
>>>
>>> In any case to drive the point home more examples are needed.
>>>
>>> The Boolean example is the minimal example and as such is interesting.
>>> But it is a borderline case which just illustrates that Smalltalk goes
>>> a long way to implement the object and message pattern consistently.
>>>
>>> The Pillar example is fine but too terse.
>>> For people who already understand the issue just a reference is fine.
>>> But for people new to the concept of replacing a case statement with a
>>> class hierarchy it is too short.
>>>
>>> Elaborate!
>>>
>>>
>>> E.g. have a diagram for a subset of the hierarchy
>>>
>>> PRObject #(''properties'')
>>> PRDocumentItem #(''counter'')
>>> PRDocumentGroup #(''children'')
>>> PRDocument #()
>>> PRHeader #(''level'')
>>> PRList #()
>>> PROrderedList #()
>>> PRUnorderedList #()
>>> PRParagraph #()
>>> PRReference #(''reference''
>>> ''parameters'')
>>> PRFigure #()
>>> PRSlide #(''title'' ''label'')
>>> PRText #(''text'')'
>>>
>>> And show all the emitHTML: messages.
>>>
>>>
>>> And go for a third example, e.g. from Morphic or Bloc
>>>
>>>
>>> position:
>>> extent:
>>> color:
>>> owner:
>>> submorphs:
>>> drawOn: aCanvas
>>>
>>>
>>> Meaning of last sentence is not clear.
>>>
>>> <citation>
>>> Remember that when we execute a method (and also write it), one key
>>> information we get is that the receiver from this class or one of its
>>> subclasses as we will later.
>>> <citation>
>>>
>>>
>>> Regards
>>>
>>> Hannes
>>>
>>> On 9/11/17, Ricardo Pacheco <ricardo.pacheco.rol...@gmail.com> wrote:
>>>> Looks Great, congratulations!! I just read it and has a couple of
>>>> mistakes
>>>> in the first figures. The return value of the false (2.3, 2.4).
>>>>
>>>> Regards
>>>> Ricardo
>>>>
>>>> El sept. 11, 2017 12:12 AM, "Stephane Ducasse" <stepharo.s...@gmail.com>
>>>> escribió:
>>>>
>>>> Hi
>>>>
>>>> after this crazy esug I took a long bus and I wrote one missing
>>>> chapter for the forhtcoming bus.
>>>> I plan to have a first full version for 1 of October :)
>>>>
>>>> I reorganised and massively clean the book contents.
>>>>
>>>> Comments are welcome in any form.
>>>>
>>>> Stef
>>>>
>>>> https://github.com/SquareBracketAssociates/LearningOOPWithPharo
>>>>
>>>
>>
>>
>
