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encoders/base.py

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+# tag::importlib[]
+import importlib
+# end::importlib[]
+
+__all__ = [
+    'Encoder',
+    'get_encoder_by_name',
+]
+
+
+# tag::base_encoder[]
+class Encoder:
+    def name(self):  # <1>
+        raise NotImplementedError()
+
+    def encode(self, game_state):  # <2>
+        raise NotImplementedError()
+
+    def encode_point(self, point):  # <3>
+        raise NotImplementedError()
+
+    def decode_point_index(self, index):  # <4>
+        raise NotImplementedError()
+
+    def num_points(self):  # <5>
+        raise NotImplementedError()
+
+    def shape(self):  # <6>
+        raise NotImplementedError()
+
+# <1> Lets us support logging or saving the name of the encoder our model is using.
+# <2> Turn a Go board into a numeric data.
+# <3> Turn a Go board point into an integer index.
+# <4> Turn an integer index back into a Go board point.
+# <5> Number of points on the board, i.e. board width times board height.
+# <6> Shape of the encoded board structure.
+# end::base_encoder[]
+
+
+# tag::encoder_by_name[]
+def get_encoder_by_name(name, board_size):  # <1>
+    if isinstance(board_size, int):
+        board_size = (board_size, board_size)  # <2>
+    module = importlib.import_module('tugo.encoders.' + name)
+    constructor = getattr(module, 'create')  # <3>
+    return constructor(board_size)
+
+# <1> We can create encoder instances by referencing their name.
+# <2> If board_size is one integer, we create a square board from it.
+# <3> Each encoder implementation will have to provide a "create" function that provides an instance.
+# end::encoder_by_name[]