[SciPy-user] scipy 0.4.4 problems with converters.blitz

[Stefan van der Walt]

On Sun, Jan 29, 2006 at 03:29:03PM +0100, Christian Kristukat wrote:
> Thanks! That works.
> Unfortunately the inline code that used to work before still doesn't compile. It
> seems to be related to the support code I'm using. In the error message below
> dist(double, double, int, double) is a function of the support code. Have there
> been changes to weave that I'm not aware of?
> 
> /home/ck/.python24_compiled/sc_9824b12a96792c10b5fdb725f9caa3c44.cpp: In
> function ‘PyObject* compiled_func(PyObject*, PyObject*)’:
> /home/ck/.python24_compiled/sc_9824b12a96792c10b5fdb725f9caa3c44.cpp:837: error:
> ISO C++ says that these are ambiguous, even though the worst conversion for the
> first is better than the worst conversion for the second:
> /usr/lib/python2.4/site-packages/scipy/weave/blitz/blitz/array-impl.h:1910:
> note: candidate 1: typename blitz::SliceInfo<P_numtype, T1, T2,
> blitz::nilArraySection, blitz::nilArraySection, blitz::nilArraySection,
> blitz::nilArraySection, blitz::nilArraySection, blitz::nilArraySection,
> blitz::nilArraySection, blitz::nilArraySection, blitz::nilArraySection>::T_slice
> blitz::Array<T, N>::operator()(T1, T2) const [with T1 = long int, T2 = int,
> P_numtype = double, int N_rank = 2]
> /usr/lib/python2.4/site-packages/scipy/weave/blitz/blitz/array-impl.h:1637:
> note: candidate 2: P_numtype& __restrict__ blitz::Array<T, N>::operator()(int,
> int) [with P_numtype = double, int N_rank = 2]
> /home/ck/.python24_compiled/sc_9824b12a96792c10b5fdb725f9caa3c44.cpp:837: error:
> cannot convert ‘blitz::Array<double, 0>’ to ‘double’ for argument ‘2’ to ‘double
> dist(double, double, int, double)’

Don't you just love C++'s clear and descriptive compiler error's?
This error also popped up in my code after a compiler upgrade (to
GCC4, IIRC).  Seems that GCC4 is a lot more pedantic than 3.2.  You
should be able to work around the problem by casting the value before
passing it to your function, i.e.

dist(static_cast<double>(whatever_you_had_here), ...)

I had the problem with a function being called like

dist(3, 4, 1, 1);

which would only compile if I did

dist(3.0, 4.0, 1, 1.0);

in order to explicitly make the parameters doubles.

Or maybe I'm totally off track, but it was worth a try!

Regards
Stéfan