[Python-Dev] For review: PEP 285: Adding a bool type (original) (raw)

Guido van Rossum guido@python.org
Fri, 08 Mar 2002 15:39:36 -0500

Question: what will happen with all the return 1 or return 0 etc in the std lib and in user code and in the inline doc and docs?

Ideally they would have to be changed into True and False, but there's no hurry -- 0 and 1 will continue to be valid as truth values too.

(I have found 167 return 1 in the std lib and 176 return 0, and also code like this

if os.name == 'mac': # The macintosh will select a listening socket for # write if you let it. What might this mean? def writable (self): return not self.accepting else: def writable (self): return 1 which unchanged will define a bool vs int function.)

A job for PyChecker! :-)

There are function in the std lib that return 1 on success, 0 on failure. Are there function that do the contrary like unix calls? Should these return True and False now. Maybe not?

I doubt there are any functions returning 0 for success and -1 for failure, but if there are, they should not be changed.

In distutil code I have seen at least one function documented as returning 'true' on success.

Another reason to introduce a Boolean type. :-)

Then there are really predicate function/methods, they should probably be changed?

Yes. I hope that most of the C code goes through some easy choke point that makes it simple to change a lot of these at once (e.g. using Py_True and Py_False).

but that means that the situation for the user will be ideally less muddy only when all the code uses True/False everytime it makes sense, and not 1/0.

Yes, it will take time before everything is converted. That's why we must be careful to decide if we really want this.

--Guido van Rossum (home page: http://www.python.org/~guido/)