[Freeipa-devel] [PATCH] 142 Improve default user/group object class validation

[Martin Kosek]

On Tue, 2011-10-11 at 13:57 +0300, Alexander Bokovoy wrote:
> On Tue, 11 Oct 2011, Martin Kosek wrote:
> > This was done on purpose. When you combine 2 lists in Python using +
> > operator, a new list is created without modifying the old one. Check the
> > following example:
> > 
> > >>> a = [1,2,3]
> > >>> b = [4]
> > >>> c = a+b
> > >>> print c
> > [1, 2, 3, 4]
> > >>> print a
> > [1, 2, 3]
> > >>> print b
> > [4]
> > >>> c.append(5)
> > >>> print c
> > [1, 2, 3, 4, 5]
> > >>> print a
> > [1, 2, 3]
> > >>> print b
> > [4]
> Sorry, but this is not our case:
> >>> a = [1,2,3]
> >>> b = a
> >>> b += [4]
> >>> print a
> [1, 2, 3, 4]
> >>> print b
> [1, 2, 3, 4]
> 

You are right. This is an important Python lesson for me. c=c+a is NOT
equal to c+=a as it is in C. Behold:
>>> a=[1,2,3]
>>> b=a
>>> b = b + [4]
>>> a
[1, 2, 3]
>>> b
[1, 2, 3, 4]
>>> 
>>> 
>>> a=[1,2,3]
>>> b=a
>>> b+= [4]
>>> a
[1, 2, 3, 4]
>>> b
[1, 2, 3, 4]

Updated patch attached.

Martin


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