[Python-Dev] [Python-3000] Removing 'self' from method definitions

Jim Jewett jimjjewett at gmail.com
Thu Apr 13 20:54:11 CEST 2006

(Cc to python dev, as my question is really about 2.x)

On 4/13/06, Ian Bicking <ianb at colorstudy.com> wrote:

> ...  the self in the signature (and the miscount of arguments
> in TypeError exceptions)  ...

Even in the 2.x line, the TypeError messages should be improved.

    >>> # No syntax errors when creating m()
    >>> class C:
        def m(): pass

but the method can't actually be called, and won't quite say why.

    >>> # This message is good
    >>> C.m()

    Traceback (most recent call last):
      File "<pyshell#101>", line 1, in -toplevel-
    TypeError: unbound method m() must be called with C instance as
first argument (got nothing instead)

but the obvious fix of using an instance is just confusing

    >>> C().m()

    Traceback (most recent call last):
      File "<pyshell#102>", line 1, in -toplevel-
    TypeError: m() takes no arguments (1 given)

Could it at least say something like "(1 given, including self)"?  I
suppose the argument might be named something other than self,
particularly in C code, but ... that strikes me as a smaller problem
than the mysteriously appearing invisible argument.


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