[C++-sig] working around the non-const Python C API (original) (raw)

David Abrahams dave at boost-consulting.com
Sat Dec 3 00:35:29 CET 2005

Jeremy Hylton <jeremy at alum.mit.edu> writes:

I was curious if anyone had advice on how to work around the fact that much of the Python C API asks for char* when it really intends to treat it as a const char*. An example of this behavior is the PyMethodDef struct, which has char* mlname and char* mldoc parameters. If you use a string literal, you get a warning about casting a const char* to a char*.

In C++, anyway, these are really supposed to be hard errors. The type of a string literal is char const(&)[N].

I can add a cast around each literal, but that's really ugly.

Is there a good way to avoid the warnings?

Fix Python :)

Secondarily, I know that python-dev is a bit hesitant about const correctness, but we did get some const char* types added with the new bytecode compiler. Perhaps it's worthwhile to try changing a few of the most egregious cases to use const char*.

If you can't do that, the next most good approach is to use const_cast instead of a C-style cast. Just to drive the point home :)

-- Dave Abrahams Boost Consulting www.boost-consulting.com

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