From: Simon Marchi <simon.marchi@polymtl.ca>
The initial goal of this patch was to remove the usage of
VEC(xmethod_worker_ptr) and corresponding cleanups. I ended up having
to C++ify the xmethod_worker code, to be able to have xmethod_workers
free their data in destructors, and therefore be able to use vectors of
xmethod_worker unique_ptr.
The operations in extension_language_ops that act on one instance of
xmethod_worker (get result type, get args type, invoke) are transformed
to methods of xmethod_worker. xmethod_worker becomes an abstract base
class with virtual pure methods which python_xmethod_worker implements.
The only xmethod-related operation left in extension_language_ops is
get_matching_xmethod_workers, which returns a list of xmethod_workers.
The changes are relatively straightforward, but here are some notes on
things that may raise eyebrows:
- I was not really comfortable with the value_of_xmethod function.
At
first it looks like a simple getter, so I considered making it a
method of xmethod_worker. But actually it creates a value and
transfers the ownership of the xmethod_worker to it. It would be a
bit weird and error-prone if calling a method on an object silently
removed the ownership of the object from the caller. To reflect the
behavior more accurately, I renamed it to value_from_xmethod and made
it accept an rvalue-reference (so the caller knows it gives away the
ownership). I noticed the backlink from xmethod_worker to its owning
value was not used, so I removed it.
- Some code, like get_matching_xmethod_workers, made each callee fill
a new vector, which was then merged in the result vector. I think
it's safe if we always pass the same vector around, and each
implementation just appends to it.
- The clone operation does not seem particularly useful, it is
removed
in the following patch.