Best way to implement two-dimensional array

> Also, you easily can inflate your image to ridiculous sizes with  
> class variables accidentally holding onto huge structures.  
> Maintaining an image requires a bit of discipline. It's an organic  
> thing, which quite literally has been nurtured for 30 years now  
> (with periods of hibernation of course).
>
> - Bert -
>
> On Sep 4, 2007, at 15:31 , John Almberg wrote:
>
>> Yes, that's clear, and I do intend to initialize this big table  
>> with code, mainly to make it easy for me to spot and fix typos.  
>> However, it's still cool to gain a sense of the concreteness of  
>> Smalltalk classes.
>>
>> And I find myself trying out code in a Workspace to see how things  
>> work, before encoding it in a method. I suspect interactively  
>> tweaking a class might help me figure things out before committing  
>> it to an initialize method.
>>
>> -- John
>>
>> On Sep 4, 2007, at 5:29 PM, nicolas cellier wrote:
>>
>>> However, Classes and methods are Objects which have well defined  
>>> tools to help them migrating from an image to another, even to  
>>> another Smalltalk dialect. This ease code sharing.
>>>
>>> This is less clear for arbitrary objects...
>>>
>>> That's why I restrict myself to initialize these class vars in an  
>>> initialize method in the class side, and loose some of the power  
>>> of the image...
>>>
>>> But there is a better reason:
>>> if you construct your object with some snippets of code, say in  
>>> an inspector or a debugger:
>>> MyTable at: 1 put: 30 degreesToRadians cos * 4
>>>
>>> Then your image will loose the history of construction.
>>> All it retains is 3.464101615137755 which is somehow less  
>>> expressive.
>>>
>>> Nicolas
>>>
>>> Bert Freudenberg a écrit :
>>>> Seems you've made the first step to truly understanding  
>>>> Smalltalk :)
>>>> Also you must realize that the browser is just a view into that  
>>>> live system of objects we call classes and is simply modifying  
>>>> those live objects. You could do that in an inspector as well,  
>>>> but the class browser is more specialized so it is easier to use  
>>>> for that purpose.
>>>> Welcome to Real Objects.
>>>> - Bert -
>>>> On Sep 4, 2007, at 12:19 , John Almberg wrote:
>>>>> Whoa... that worked, but the implications are a bit hard to  
>>>>> digest...
>>>>>
>>>>> So MyClass is an object in my Smalltalk image, and it can have  
>>>>> variables that I can set interactively, and the values  
>>>>> contained therein are now part of the class...
>>>>>
>>>>> I keep reading that classes are objects, but this is the first  
>>>>> time I've seen something that makes me realize that they are  
>>>>> fundamentally different than objects in other languages. I  
>>>>> guess because they are 'live', in some sense, in the Smalltalk  
>>>>> environment. That is, not just source code, but an instantiated  
>>>>> object.
>>>>>
>>>>> Talk about paradigm whiplash... I'm going to have to think  
>>>>> about this, a bit :-)
>>>>>
>>>>> Thanks!
>>>>>
>>>>> -- John
>>>>>
>>>>>> Type "MyClass", select it, press Cmd-i (or Alt-i). You get an  
>>>>>> inspector on a class - which of course is the instance of  
>>>>>> another class, as everything is an object (and hence an  
>>>>>> instance of a class) in Smalltalk. Anyway, you should see a  
>>>>>> reference to the superclass, a dictionary of all the methods,  
>>>>>> the list of instance variables and subclasses etc. Class  
>>>>>> variables are simply held in a Dictionary in the "classPool"  
>>>>>> instance variable of that class. So by inspecting that and  
>>>>>> drilling down into your class var you can modify it.
>>>>>>
>>>>>> A simpler way to get at the contents of your class var is just  
>>>>>> selecting its name in a browser showing any method of your  
>>>>>> class, and press Cmd-i there. That works because in the  
>>>>>> browser, code is evaluated in the context of the selected class.
>>>>>>
>>>>>> - Bert -
>
>
>
>
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>
> second:
> I have a few classes which I use as lookup tables, stored in
> classvars.
>
> For these I implement on the class side a fileIn/Out protocol to move
> the classVars between images like e.g.:
>
> TrainingsSamplesFehlerkategorien>>writeTrainingsSamples
>         "write the class var TrainingsSamples to a file using  
> ReferenceStreams"
>