'self' an unknown variable???

[Giorgi Lekishvili]

yes, you're right. I have done it as follows:
def write(self, filename, cols='all', format='asc'):
    if cols=='all' or cols>self.Npred:
        cols=self.Npred

Just the way you've written.

Grtz,
Giorgi

Robin Munn wrote:

> On Mon, 14 Jan 2002 10:40:22 -0800, Giorgi Lekishvili <gleki at gol.ge> wrote:
> >Hello all!
> >
> >I have written a class, with the function write. The latter is defined
> >as follows:
> >
> >def write(self, filename, matr, cols=self.Npred, format='asc'):
> >    blablabla
> >    return res
> >
> >This doesn't work. Then I changed cols=N, previously defined
> >N=self.Npred.
> >Now things ar ok.
> >
> >Why doesn't function self.some_attr in the function declaration?
>
> As Alex mentioned, the name "self" is not bound to anything at the time
> the def statement executes. The standard way to do what you're trying to
> do looks like:
>
> def write(self, filename, matr, cols=None, format='asc'):
>     if cols == None:
>         cols = self.Npred
>     blablabla
>     return res
>
> When you say "previously defined N=self.Npred", what does that mean? You
> defined N earlier as a global? In that case, what "self" variable is it
> picking up? Almost certainly not the one you intend. That way of doing
> things seems very dangerous to me; you'd be much better off using None
> as a default value and setting it inside your function. Or if you want
> to be able to pass None as a real value for cols, use some other value
> as a "default value" flag, e.g.:
>
> def write(self, filename, matr, cols=-1, format='asc'):
>     if cols == -1:
>         cols = self.Npred
>     blablabla
>     return res
>
> This is safe and is guaranteed to do what you intend. Doing it the other
> way is asking for trouble.
>
> --
> Robin Munn
> rmunn at pobox.com