Re: Is SmallInteger a really too dangerous class?

Hi folks. Sorry for the cross-post, I am not sure if it is image or vm problem.

If I implement this:

SmallInteger >> initialize
    self addInstVarName: 'Zaraza'.

I have the error: 'SmallInteger cannot be changed'

This is because SmallInteger is in the ClassBuilder >> tooDangerousClasses
and the error is in ClassBuilder >> name: className inEnvironment: env subclassOf: newSuper type: type instanceVariableNames: instVarString classVariableNames: classVarString poolDictionaries: poolString category: category unsafe: unsafe

Now....since this is Smalltalk, I can just comment something, continue, or any other kind of hack so that I can add class variables to SmallInetger.
For my CompiledMethod proxies stuff, I am using SmallIntegers and I have some crashes (one is due to a corrupt heap and Eliot said something about sizes)...I wonder if this is related to this...So the question is:  is really SMallInteger a too dangerous class so that it cannot be changed? not even adding a class variable???  does the VM assume that the class SmallInetger has a fixed size?  if true, where?

Thanks in advance

Mariano

On 12/14/2010 1:09 AM, Igor Stasenko wrote:

Notice I want to add a class variable to SmallIneteger, not instVar.

This is not really a VM question. Class variables are held in a
dictionary. The VM knows nothing about this.

And of course class vars are added by using #addClassVarName: not
#addInstVarName:.

class inst var should be ok too. Not sure what the correct message for
adding it programmatically.

Obviously that would be "self ->class<- addInstVarName: 'classInstVarName'".

BTW, you do realize that you can try all of this right in the browser, no? All you need is to go to class SmallInteger and edit the class definition. Then you can see whether it is possible to add instance variables (it's not), class variables (works fine), or class instance variables (works fine, too). And once you've tried this it should be pretty obvious that your code is broken and not the VM and/or ClassBuilder.

Cheers,
 - Andreas

 

On 13.12.2010, at 13:06, Mariano Martinez Peck wrote:

sorry, it should be

SmallInteger class >> initialize
    self addInstVarName: 'Zaraza'.

Notice I want to add a class variable to SmallIneteger, not instVar.

This is not really a VM question. Class variables are held in a dictionary. The VM knows nothing about this.

You add class variables simply by adding them to the class pool:

SmallInteger ensureClassPool.

SmallInteger classPool at: #Zaraza put: 42.

- Bert -