Fix/Simplify plugin_function

[tlambert03]

This PR simplifies and fixes some bugs in the heavily used plugin_function decorator.
It moves to the more modern inspect.Signature API, and takes advantage of the Signature.bind method to accomplish in a single line what most of the previous implementation was trying to do.

Importantly, this is fixing a big bug in the current implementation, which is that position or keyword arguments were not working. as an explanation:

def f(x):
    print(x)

# in python a positional argument can also be called as a keyword argument:
f('hi')  # prints "hi"
f(x='hi')  # also prints "hi"
# this is super important because it lets you call a function in many different
# and dynamic ways:
keyword = 'x'
f(**{keyword: 'hi'})  # also prints "hi"

the current plugin_function breaks this functionality, meaning that functions must be called in a very specific way, or they will break:

from pyclesperanto_prototype import absolute
import numpy as np
r = np.random.rand(10,10) - 0.5

absolute(r)  # works fine
absolute(source=r)  # raises TypeError

pyclesperanto_prototype/pyclesperanto_prototype/_tier0/_execute.py in execute(anchor, opencl_kernel_filename, kernel_name, global_size, parameters, prog, constants, image_size_independent_kernel_compilation)
    211             arguments.append(np.array([value], np.float32))
    212         else:
--> 213             raise TypeError(
    214                 f"other types than float and int aren`t supported yet for parameters {key} : {value} . \n"
    215                 f"function {kernel_name}"

TypeError: other types than float and int aren`t supported yet for parameters src : [[ 0.42569358  0.41798918  0.487596    0.21005139 -0.19382348 -0.40420797

this PR fixes that...

however, I'm still having a bit of an issue with tests, because there was one more thing I'm struggling to figure out here. The output_creator function may be one of many of the functions in _create.py, however each of those has a very different signature (some take *args, some do not) ... so there too, extra logic is required in plugin_function to call the output_creator in just the right way depending on the context. Can you help me understand the intent there? Should output_creator usually just receive the positional arguments provided to the function? something different?

[haesleinhuepf]

Awesome @tlambert03 , the new code is so short! ❤️

Closes #94

I'll send a PR to your repo for fixing the failing tests...

[codecov-io]

Codecov Report

Merging #95 (2333f21) into master (d9abb4f) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #95      +/-   ##
==========================================
- Coverage   91.33%   91.31%   -0.02%     
==========================================
  Files         474      474              
  Lines        7478     7462      -16     
==========================================
- Hits         6830     6814      -16     
  Misses        648      648              

Impacted Files	Coverage Δ
pyclesperanto_prototype/_tier0/_plugin_function.py	100.00% <100.00%> (ø)
...prototype/_tier2/_maximum_of_touching_neighbors.py	90.90% <100.00%> (ø)
...to_prototype/_tier2/_mean_of_touching_neighbors.py	90.90% <100.00%> (ø)
..._prototype/_tier2/_median_of_touching_neighbors.py	45.45% <100.00%> (ø)
...prototype/_tier2/_minimum_of_touching_neighbors.py	90.90% <100.00%> (ø)
...to_prototype/_tier2/_mode_of_touching_neighbors.py	90.90% <100.00%> (ø)
...tier2/_standard_deviation_of_touching_neighbors.py	90.90% <100.00%> (ø)

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[tlambert03]

thanks! This is mergeable now... I still think there's some room for improvement on the output_creator functions. Specifically I don't like that we have to call it like this output_creator(*bound.args[:len(args)]) (because len(args) there is dependent on how the outer function was called... and that's a little wonky). I think the fix would require modifying the create functions themselves to have a unified calling signature, but I'm not sure how widely those functions are used elsewhere, so not touching that here.

[haesleinhuepf]

I don't like that we have to call it like this output_creator(*bound.args[:len(args)]) (because len(args) there is dependent on how the outer function was called...

Yes! I also don't like that either. I struggled hard to make it work earlier and would love to come up with a better solution. You should see the solution on Java side.... It's sooo much worse ;-)

I will continue thinking about it.

Thanks for this PR!

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.31%. Comparing base (d9abb4f) to head (2333f21).
Report is 1047 commits behind head on master.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master      #95      +/-   ##
==========================================
- Coverage   91.33%   91.31%   -0.02%     
==========================================
  Files         474      474              
  Lines        7478     7462      -16     
==========================================
- Hits         6830     6814      -16     
  Misses        648      648              

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