minor refactorings

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

@@ -0,0 +1,75 @@
+#!/usr/bin/env python3
+
+from importlib import import_module
+import sys
+
+
+SP    = '\N{SPACE}'
+HLIN  = '\N{BOX DRAWINGS LIGHT HORIZONTAL}' * 2 + SP        # ──
+VLIN  = '\N{BOX DRAWINGS LIGHT VERTICAL}' + SP * 3          # │
+TEE   = '\N{BOX DRAWINGS LIGHT VERTICAL AND RIGHT}' + HLIN  # ├──
+ELBOW = '\N{BOX DRAWINGS LIGHT UP AND RIGHT}' + HLIN        # └──
+
+
+def subclasses(cls):
+    try:
+        return cls.__subclasses__()
+    except TypeError:  # handle the `type` type
+        return cls.__subclasses__(cls)
+
+
+def tree(cls, level=0, last_sibling=True):
+    yield cls, level, last_sibling
+    chidren = subclasses(cls)
+    if chidren:
+        last = chidren[-1]
+        for child in chidren:
+            yield from tree(child, level + 1, child is last)
+
+
+def render_lines(tree_generator):
+    cls, _, _ = next(tree_generator)
+    yield cls.__name__
+    prefix = ''
+    for cls, level, last in tree_generator:
+        prefix = prefix[: 4 * (level - 1)]
+        prefix = prefix.replace(TEE, VLIN).replace(ELBOW, SP * 4)
+        prefix += ELBOW if last else TEE
+        yield prefix + cls.__name__
+
+
+def draw(cls):
+    for line in render_lines(tree(cls)):
+        print(line)
+
+
+def parse(name):
+    if '.' in name:
+        return name.rsplit('.', 1)
+    else:
+        return 'builtins', name
+
+
+def main(name):
+    module_name, cls_name = parse(name)
+    try:
+        cls = getattr(import_module(module_name), cls_name)
+    except ModuleNotFoundError:
+        print(f'*** Could not import {module_name!r}.')
+    except AttributeError:
+        print(f'*** {cls_name!r} not found in {module_name!r}.')
+    else:
+        if isinstance(cls, type):
+            draw(cls)
+        else:
+            print(f'*** {cls_name!r} is not a class.')
+
+
+if __name__ == '__main__':
+    if len(sys.argv) == 2:
+        main(sys.argv[1])
+    else:
+        print('Usage:'
+            f'\t{sys.argv[0]} Class          # for builtin classes\n'
+            f'\t{sys.argv[0]} package.Class  # for other classes'
+        )