reassign to builtin possible !?

[Chris Mellon]

On Jan 3, 2008 8:05 AM, Tim Chase <python.list at tim.thechases.com> wrote:
> >> But you can't alter the values for True/False globally with this.
> >
> > Are you sure ? what about the following example ?
> > Is this also shadowing ?
> >
> >>>> import __builtin__
> >>>> __builtin__.True = False
> >>>> __builtin__.True
> > False
>
> It doesn't seem to screw things up globally
>
>  >>> import __builtin__
>  >>> t = __builtin__.True
>  >>> __builtin__.True = False
>  >>> __builtin__.False = t
>  >>> True
> False
>  >>> False
> True
>  >>> 1 == 1
> True
>  >>> import os
>  >>> os.path.isdir('.')
> True
>  >>> #if they were globally redefined, this would be False
>  >>> #you'd have to actually reference __builtin__.True
>
> My thought would be if you do something as daft as
> redefining/shadowing True and False, you get the headaches that
> ensue.  Fortunately, since Python is explicit, you can trace back
> through the code and see where the inanity occurred.
> Additionally, any scoping rules mean that programmer stupidity
> can't leak too badly outside the scope of the block containing
> the stupidity.
>
> It's the old "DIHWIDT! WDDT!" ("Doctor, it hurts when I do
> this!", "well don't do that!") syndrome.
>

In Py3k this will be a syntax error, like assigning to None is now.
Possibly also in 2.6.