Adapter Patterns

Author: MilovanTomasevic

src/1_patterns/3_StructuralPatterns/1_Adapter/1_no_caching.py

@@ -0,0 +1,69 @@
+class Point:
+    def __init__(self, x, y):
+        self.y = y
+        self.x = x
+
+
+def draw_point(p):
+    print('.', end='')
+
+
+# ^^ you are given this
+
+# vv you are working with this
+class Line:
+    def __init__(self, start, end):
+        self.end = end
+        self.start = start
+
+
+class Rectangle(list):
+    """ Represented as a list of lines. """
+
+    def __init__(self, x, y, width, height):
+        super().__init__()
+        self.append(Line(Point(x, y), Point(x + width, y)))
+        self.append(Line(Point(x + width, y), Point(x + width, y + height)))
+        self.append(Line(Point(x, y), Point(x, y + height)))
+        self.append(Line(Point(x, y + height), Point(x + width, y + height)))
+
+
+class LineToPointAdapter(list):
+    count = 0
+
+    def __init__(self, line):
+        self.count += 1
+        print(f'{self.count}: Generating points for line '
+              f'[{line.start.x},{line.start.y}]→'
+              f'[{line.end.x},{line.end.y}]')
+
+        left = min(line.start.x, line.end.x)
+        right = max(line.start.x, line.end.x)
+        top = min(line.start.y, line.end.y)
+        bottom = min(line.start.y, line.end.y)
+
+        if right - left == 0:
+            for y in range(top, bottom):
+                self.append(Point(left, y))
+        elif line.end.y - line.start.y == 0:
+            for x in range(left, right):
+                self.append(Point(x, top))
+
+
+
+
+def draw(rcs):
+    print("\n\n--- Drawing some stuff ---\n")
+    for rc in rcs:
+        for line in rc:
+            adapter = LineToPointAdapter(line)
+            for p in adapter:
+                draw_point(p)
+
+if __name__ == '__main__':
+    rs = [
+        Rectangle(1, 1, 10, 10),
+        Rectangle(3, 3, 6, 6)
+    ]
+    draw(rs)
+    draw(rs)

src/1_patterns/3_StructuralPatterns/1_Adapter/2_with_caching.py

@@ -0,0 +1,84 @@
+class Point:
+    def __init__(self, x, y):
+        self.y = y
+        self.x = x
+
+
+def draw_point(p):
+    print('.', end='')
+
+
+# ^^ you are given this
+
+# vv you are working with this
+class Line:
+    def __init__(self, start, end):
+        self.end = end
+        self.start = start
+
+
+class Rectangle(list):
+    """ Represented as a list of lines. """
+
+    def __init__(self, x, y, width, height):
+        super().__init__()
+        self.append(Line(Point(x, y), Point(x + width, y)))
+        self.append(Line(Point(x + width, y), Point(x + width, y + height)))
+        self.append(Line(Point(x, y), Point(x, y + height)))
+        self.append(Line(Point(x, y + height), Point(x + width, y + height)))
+
+
+class LineToPointAdapter:
+    count = 0
+    cache = {}
+
+    def __init__(self, line):
+        self.h = hash(line)
+        if self.h in self.cache:
+            return
+
+        super().__init__()
+        self.count += 1
+        print(f'{self.count}: Generating points for line ' +
+              f'[{line.start.x},{line.start.y}]→[{line.end.x},{line.end.y}]')
+
+        left = min(line.start.x, line.end.x)
+        right = max(line.start.x, line.end.x)
+        top = min(line.start.y, line.end.y)
+        bottom = min(line.start.y, line.end.y)
+
+        points = []
+
+        if right - left == 0:
+            for y in range(top, bottom):
+                points.append(Point(left, y))
+        elif line.end.y - line.start.y == 0:
+            for x in range(left, right):
+                points.append(Point(x, top))
+
+        self.cache[self.h] = points
+
+    def __iter__(self):
+        return iter(self.cache[self.h])
+
+def draw(rcs):
+    print('Drawing some rectangles...')
+    for rc in rcs:
+        for line in rc:
+            adapter = LineToPointAdapter(line)
+            for p in adapter:
+                draw_point(p)
+    print('\n')
+
+
+if __name__ == '__main__':
+    rs = [
+        Rectangle(1, 1, 10, 10),
+        Rectangle(3, 3, 6, 6)
+    ]
+
+    draw(rs)
+    draw(rs)
+
+    # can define your own hashes or use the defaults
+    print(hash(Line(Point(1, 1), Point(10, 10))))