[Python-Dev] Re: str does not default to repr if a base classhas str (original) (raw)

Terry Reedy tjreedy at udel.edu
Mon May 17 12:15:12 EDT 2004

"Edward C. Jones" <edcjones at erols.com> wrote in message news:40A8D37B.7030807 at erols.com...

# In the code below, "a.str()" does not default to "a.repr() as # might be expected. It finds the "str" in the base class X. The # Reference Manual, section 3.3.1, says: # If a class defines repr() but not str(), then repr() is # also used when an 'informal' string representation of instances of # that class is required. # If the reader is in lawyer mode, the documentation is correct.

I don't think one has to be in lawyer mode to think that 'attribute x is defined by class C' == 'C.x returns an object without exception', whether the production is by direct lookup, inheritance, or calculation. It is possible that 'defines' could be defined better.

The current behavior seems to be

try: f = i.str except AttributeError: try: f = i.repr except AttributeError f = <default stringifier that produces '<class instance at 0x####>' form > s = f(i)

Your implied and underdefined alternative would require special casing of str lookup to not use inheritance.

# Is the current behavior what was intended? What should the behavior be?

Since the current behavior is hard to see as a bug, I think it should stay as is, if it has been consistently so forever, even if something else might have been once preferred.

Terry J. Reedy

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