why am I not allowed to redefine a class ?

[Stef Mientki]

thanks guys.

cheers,
Stef

Terry Reedy wrote:
> Stef Mientki wrote:
>> hello,
>>
>> although this is not a real problem for me,
>> it was caused by a copying, instead of moving, a piece of code.
>> But I don't understand at all why the code below gives the error.
>> class derived_class, is defined twice,
>> the error is cuase by the second instance creation "test2="
>> for me even weirder, if I create test2 in another module, everything 
>> works perfect ???
>> Any explanation would be welcome.
>
> A different version of what Arnaud D. said:
>
>> ==== start of code ===
>> class base_class ( object ) :
>>  def __init__ ( self ) :
>>    pass
>>
>> class derived_class ( base_class ) :
>>  def __init__ ( self ) :
>>    base_class.__init__ ( self )
>>
>> class final_class_1 ( derived_class ) :
>
> In this line, 'derived_class' is evaluated when the class is defined
>
>>  def __init__ ( self ) :
>>    derived_class.__init__ ( self )
>
> In this line, 'devired_class' is evaluated when the class is 
> instantiated and __init__ is called.
>
>> test1 = final_class_1 ()
>
> Here, the object corresponding to 'derived_class in f_c_1.__init__is 
> the same as when f_c_1 was created.
>
>> class derived_class ( base_class ) :
>>  def __init__ ( self ) :
>>    base_class.__init__ ( self )
>>
>> test2 = final_class_1 ()
>
> Here, object corresponding to 'derived_class in f_c_1.__init__is no 
> longer the same as when f_c_1 was created.
>
>
>> ==== end of code =====
>>
>> ==== error meassage =====
>> Traceback (most recent call last):
>>  File "D:\Data_Python_25\PyLab_Works\module1.py", line 19, in <module>
>>    test2 = final_class_1 ()
>>  File "D:\Data_Python_25\PyLab_Works\module1.py", line 11, in __init__
>>    derived_class.__init__ ( self )
>> TypeError: unbound method __init__() must be called with derived_class 
>
> This refers to the second 'derived_class', and f_c_1 ia *not* a 
> subclass of *that* class object.
>
>> instance as first argument (got final_class_1 instance instead)
>
> tjr
>
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