Simplify function call creation (pyccel#2020)

Add the magic method `__call__` to `FunctionDef`, `Interface` and
`PyccelFunctionDef` to create `FunctionCall` nodes. This makes the code
more readable as the verbose `FunctionCall(func, [arg1, arg2])` can now
be written as `func(arg1, arg2)`.

Author: EmilyBourne

CHANGELOG.md

@@ -46,6 +46,7 @@ All notable changes to this project will be documented in this file.
 -   Add a warning about containers in lists.
 -   \[INTERNALS\] Add abstract class `SetMethod` to handle calls to various set methods.
 -   \[INTERNALS\] Added `container_rank` property to `ast.datatypes.PyccelType` objects.
+-   \[INTERNALS\] Add a `__call__` method to `FunctionDef` to create `FunctionCall` instances.
 -   \[DEVELOPER\] Added an improved traceback to the developer-mode errors for errors in function calls.
 
 ### Fixed

pyccel/ast/core.py

@@ -2765,6 +2765,11 @@ def result_pointer_map(self):
         """
         return self._result_pointer_map
 
+    def __call__(self, *args, **kwargs):
+        arguments = [a if isinstance(a, FunctionCallArgument) else FunctionCallArgument(a) for a in args]
+        arguments += [FunctionCallArgument(a, keyword=key) for key, a in kwargs.items()]
+        return FunctionCall(self, arguments)
+
 class InlineFunctionDef(FunctionDef):
     """
     Represents a function definition for an inline function.
@@ -2955,6 +2960,9 @@ def __getnewargs__(self):
             'argument_description':self._argument_description}
         return args, kwargs
 
+    def __call__(self, *args, **kwargs):
+        return self._cls_name(*args, **kwargs)
+
 class Interface(PyccelAstNode):
     """
     Class representing an interface function.
@@ -3173,6 +3181,11 @@ def type_match(call_arg, func_arg):
                         severity='fatal')
         return  self._functions[j]
 
+    def __call__(self, *args, **kwargs):
+        arguments = [a if isinstance(a, FunctionCallArgument) else FunctionCallArgument(a) for a in args]
+        arguments += [FunctionCallArgument(a, keyword=key) for key, a in kwargs.items()]
+        return FunctionCall(self, arguments)
+
 class FunctionAddress(FunctionDef):
     """
     Represents a function address.

pyccel/codegen/printing/fcode.py

@@ -553,7 +553,7 @@ def _get_comparison_operator(self, element_type, imports_and_macros):
             compare_func = FunctionDef('complex_comparison',
                                        [FunctionDefArgument(tmpVar_x), FunctionDefArgument(tmpVar_y)],
                                        [FunctionDefResult(Variable(PythonNativeBool(), 'c'))], [])
-            lt_def = FunctionCall(compare_func, [tmpVar_x, tmpVar_y])
+            lt_def = compare_func(tmpVar_x, tmpVar_y)
         else:
             lt_def = PyccelAssociativeParenthesis(PyccelLt(tmpVar_x, tmpVar_y))