add keyword argument to import-module to import submodules

[digikar99]

DO NOT MERGE YET!

In addition to this, there's one more change (not yet backported/committed) that adds import statements to the start of every function. So, if numpy were imported as np, and one were to call np:add after the process stops, one gets a numpy not defined error. To avoid this, the first statement of np:add becomes (python-exec "import numpy as np"). Should this be committed?

I don't think this breaks anyone's code; one may get a performance penalty though; but as it is, this project does not have much focus on speed.

DO NOT MERGE YET!

[bendudson]

Thanks for this! How does the code work out which imports to include? Is this just replaying any python-import calls the user has made, so they persist across python sessions? I agree that the performance penalty should not be a big issue: Python eliminates most of the cost of repeated imports, and py4cl calls in tight loops is likely to always be costly. I think my worry is more that other things in the python process (like variables, functions etc.) are not persistent across python process restarts, so this introduces a special handling for imports. It may also be that users want to restart a python session to get rid of an import.

[digikar99]

How does the code work out which imports to include?

This simply during the calls to import-function and import-module. In py4cl2, I have kept this as an optional :safety keyword parameter to defpyfun and defpymodule. Hmm, keeping the :safety nil instead of the default t in py4cl2 should avoid breaking any possible user code; the statements are only added if safety is t.

So, the source form of math:sqrt is

(LAMBDA (&OPTIONAL (MATH::X 'NIL))
      "Return the square root of x."
      (BLOCK MATH:SQRT
        NIL
        (PYEXEC "import math") ; <================================ the addition of this line
        (RAW-PYEVAL "math.sqrt" "(" (PYTHONIZE MATH::X) "," ")")))

instead of

(LAMBDA (&REST PY4CL::ARGS)
      "Return the square root of x."
      (BLOCK MATH:SQRT (APPLY #'PY4CL:PYTHON-CALL "math.sqrt" PY4CL::ARGS)))

(Ignore the other changes)

[digikar99]

Oh yes, should I proceed with the :safety?