Add and declare to Python functions
double_mat_cm() --- compute 2* a column-major matrix
double_mat_rm() --- compute 2* a row-major matrix
to 'eigen.cpp' tests / example.
Passing a non-contiguous one-dimensional numpy array gives incorrect
results, so three of these tests fail. The only one passing is the
simple case where the numpy array is contiguous and we are building a
column-major vector. Subsequent commit will fix the three failing
cases.
Sergey Lyskov pointed out that the trampoline mechanism used to override
virtual methods from within Python caused unnecessary overheads when
instantiating the original (i.e. non-extended) class.
This commit removes this inefficiency, but some syntax changes were
needed to achieve this. Projects using this features will need to make a
few changes:
In particular, the example below shows the old syntax to instantiate a
class with a trampoline:
class_<TrampolineClass>("MyClass")
.alias<MyClass>()
....
This is what should be used now:
class_<MyClass, std::unique_ptr<MyClass, TrampolineClass>("MyClass")
....
Importantly, the trampoline class is now specified as the *third*
argument to the class_ template, and the alias<..>() call is gone. The
second argument with the unique pointer is simply the default holder
type used by pybind11.
args was derived from list, but cpp_function::dispatcher sends a tuple to it->impl (line #346 and #392 in pybind11.h). As a result args::size() and args::operator[] don't work at all. On my mac args::size() returns -1. Making args a subclass of tuple fixes it.
This somewhat heavyweight solution will avoid size_t/long long/long/int
mismatches on various platforms once and for all. The previous template
overloads could e.g. not handle size_t on Darwin.
One gotcha: the 'format_descriptor<T>::value()' syntax changed to just
'format_descriptor<T>::value'
