On 2/10/06, Guido van Rossum <[EMAIL PROTECTED]> wrote:
> OMG. Are we now adding 'const' modifiers to random places? I thought
> "const propagation hell" was a place we were happily avoiding by not
> falling for that meme. What changed?
I added some const to several API functions that take char* but
typically called by passing string literals. In C++, a string literal
is a const char* so you need to add a const_cast<> to every call site,
which is incredibly cumbersome. After some discussion on python-dev,
I made changes to a small set of API functions and chased the
const-ness the rest of the way, as you would expect. There was
nothing random about the places const was added.
I admit that I'm also puzzled by Jack's specific question. I don't
understand why an array passed to PyArg_ParseTupleAndKeywords() would
need to be declared as const. I observed the problem in my initial
changes but didn't think very hard about the cause of the problem.
Perhaps someone with better C/C++ standards chops can explain.
Jeremy
>
> --Guido
>
> On 2/10/06, Jack Jansen <[EMAIL PROTECTED]> wrote:
> > I keep running into problems with the "const" modifications to
> > PyArg_ParseTupleAndKeywords() (rev. 41638 by Jeremy).
> >
> > I have lots of code of the form
> > char *kw[] = {"itself", 0};
> >
> > if (PyArg_ParseTupleAndKeywords(_args, _kwds, "O&", kw,
> > CFTypeRefObj_Convert, &itself)) ...
> > which now no longer compiles, neither with C nor with C++ (gcc4, both
> > MacOSX and Linux). Changing the kw declaration to "const char *kw[]"
> > makes it compile again.
> >
> > I don't understand why it doesn't compile: even though the
> > PyArg_ParseTupleAndKeywords signature promises that it won't change
> > the "kw" argument I see no reason why I shouldn't be able to pass a
> > non-const argument.
> >
> > And to make matters worse adding the "const" of course makes the code
> > non-portable to previous versions of Python (where the C compiler
> > rightly complains that I'm passing a const object through a non-const
> > parameter).
> >
> > Can anyone enlighten me?
> > --
> > Jack Jansen, <[EMAIL PROTECTED]>, http://www.cwi.nl/~jack
> > If I can't dance I don't want to be part of your revolution -- Emma
> > Goldman
> >
> >
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> >
>
>
> --
> --Guido van Rossum (home page: http://www.python.org/~guido/)
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