Python interfaces

[EmilyBourne]

Describe the bug Interfaces in python assume that the code is the same in all languages and therefore print the body of the first FunctionDef with all the decorators. However the code generated by pyccel is not always the same (e.g. if the input can be either a boolean or a numeric type)

To Reproduce Provide code to reproduce the behavior:

@types('float')
@types('complex')
def get_imag(a):
    import numpy as np
    return np.imag(a)

Provide the generated code, or the error message:

from pyccel.decorators import types

@types('float')
@types('complex')
def get_imag(a):

    from numpy import imag
    return 0.0

Expected behavior There are multiple possible solutions:

• We could raise an error, complaining about incompatible types
• We could ensure all code is preserved so it is identical at printing (I don't like this solution as the value of np.imag(a) for all types other than complex would have to be corrected manually for every language

• We could print all function def bodies, and collect versions giving the same code:

  from pyccel.decorators import types
  
  @types('float')
  @types('complex')
  def get_imag(a):
      if isinstance(a, float):
          from numpy import imag
          return 0.0
      else:
          from numpy import imag
          return (a).imag

  but this code is not understood by pyccel

• We could generate multiple translatable functions and a wrapper:

  from pyccel.decorators import types
  
  @types('float')
  def get_imag_00(a):
      from numpy import imag
      return 0.0
  
  @types('complex')
  def get_imag_01(a):
      from numpy import imag
      return (a).imag
  
  def get_imag(a):
      if isinstance(a, float):
           return get_imag_00(a)
      elif isinstance(a, complex):
           return get_imag_01(a)
      else:
           raise TypeError("Unexpected type")

Language python

Additional context This is causing some of our tests to be incomplete, but the tests could also be fixed by avoiding interfaces. In an ideal world, the dtype should be a pytest parameter

[ratnania]

What if we have a python decorator that will concatenate the function name with the associated type, in order to avoid the last defined function get_imag?

[EmilyBourne]

What if we have a python decorator that will concatenate the function name with the associated type, in order to avoid the last defined function get_imag?

I'm not sure that we can avoid the last function no matter the name of the functions as in pyccel we always aim to have a result that can be called in the same way as the original code

[EmilyBourne]

Duplicate of #885