Use class setter properties if present

[adrianomartinelli]

Objective

Add support of class properties when setting attributes. This pull request is based on this discussion with @rusty1s .

Problem

If Data is subclassed all attributes are set with __setattr__ method. This prevents users from implementing validation logic for attributes (like ensuring a certain dtype). In the example below, the developer would like to ensure that my_attr can only hold int values. This is currently not possible with the implemented __setattr__ method.

  class Graph(Data):
      def __init__(self):
          super().__init__()
          self.my_attr = 1.0
          self.my_attr2 = 2

      @property
      def my_attr(self):
          return self._my_attr

      @my_attr.setter
      def my_attr(self, value):
          self._my_attr = int(value)

Solution

The proposed solution checks if the class implements a setter method for the attribute or defaults to the standard behaviour

    def __setattr__(self, key: str, value: Any):
        propobj = getattr(self.__class__, key, None)
        if propobj is None or propobj.fset is None:
            setattr(self._store, key, value)
        else:
            propobj.fset(self, value)

This implementation is tested with test_data_subclass_setter in test/data/test_data.py. Coverage of data.py is 89%

Best,
Adriano

[codecov]

Codecov Report

Merging #4682 (3321a2e) into master (6cb12ea) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #4682   +/-   ##
=======================================
  Coverage   82.88%   82.88%           
=======================================
  Files         318      318           
  Lines       16817    16820    +3     
=======================================
+ Hits        13939    13942    +3     
  Misses       2878     2878           

Impacted Files	Coverage Δ
torch_geometric/data/data.py	90.78% <100.00%> (+0.07%)	⬆️

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[rusty1s]

Amazing. Thank you!