ch17: update from book draft

17-it-generator/tree/step4/test_tree.py

@@ -0,0 +1,76 @@
+from tree import tree
+
+
+def test_1_level():
+    class One: pass
+    expected = [('One', 0)]
+    result = list(tree(One))
+    assert expected == result 
+
+
+def test_2_levels_4_leaves():
+    class Branch: pass
+    class Leaf1(Branch): pass
+    class Leaf2(Branch): pass
+    class Leaf3(Branch): pass
+    class Leaf4(Branch): pass
+    expected = [
+        ('Branch', 0),
+            ('Leaf1', 1),
+            ('Leaf2', 1),
+            ('Leaf3', 1),
+            ('Leaf4', 1),
+    ]
+    result = list(tree(Branch))
+    assert expected == result 
+
+
+def test_3_levels_1_leaf():
+    class X: pass
+    class Y(X): pass
+    class Z(Y): pass
+    expected = [
+        ('X', 0),
+            ('Y', 1),
+                ('Z', 2),
+    ]
+    result = list(tree(X))
+    assert expected == result 
+
+
+def test_4_levels_1_leaf():
+    class Level0: pass
+    class Level1(Level0): pass
+    class Level2(Level1): pass
+    class Level3(Level2): pass
+    expected = [
+        ('Level0', 0),
+            ('Level1', 1),
+                ('Level2', 2),
+                    ('Level3', 3),
+    ]
+
+    result = list(tree(Level0))
+    assert expected == result 
+
+
+def test_4_levels_3_leaves():
+    class A: pass
+    class B1(A): pass
+    class C1(B1): pass
+    class D1(C1): pass
+    class B2(A): pass
+    class D2(C1): pass
+    class C2(B2): pass
+    expected = [
+        ('A', 0),
+            ('B1', 1),
+                ('C1', 2),
+                    ('D1', 3),
+                    ('D2', 3),
+            ('B2', 1),
+                ('C2', 2),
+    ]
+
+    result = list(tree(A))
+    assert expected == result 

17-it-generator/tree/step4/tree.py

@@ -0,0 +1,20 @@
+def tree(cls):
+    yield cls.__name__, 0
+    yield from sub_tree(cls)
+
+
+# tag::SUB_TREE[]
+def sub_tree(cls):
+    for sub_cls in cls.__subclasses__():
+        yield sub_cls.__name__, 1
+        for sub_sub_cls in sub_cls.__subclasses__():
+            yield sub_sub_cls.__name__, 2
+            for sub_sub_sub_cls in sub_sub_cls.__subclasses__():
+                yield sub_sub_sub_cls.__name__, 3
+# end::SUB_TREE[]
+
+
+if __name__ == '__main__':
+    for cls_name, level in tree(BaseException):
+        indent = ' ' * 4 * level
+        print(f'{indent}{cls_name}')