bagrow · August 3, 2023 16:21 · Dec 6, 2016 · Dec 6, 2016
diff --git a/method_chaining.py b/method_chaining.py
@@ -34,18 +34,16 @@ def train_prod(self, beta):
         return self
 
 
-if __name__ == "__main__":
-
-    # initialize the object:
-    jv = Jarvis([1,2,3,4])
-
-    # use its methods 
-    jv.train_sum(2)
-    jv.train_prod(10)
-    print(jv.data)
-
-
-    # the same thing with method chaining:
-    jv = Jarvis([1,2,3,4])
-
-    print(jv.train_sum(2).train_prod(10).data)
+# initialize the object:
+jv = Jarvis([1,2,3,4])
+
+# use its methods 
+jv.train_sum(2)
+jv.train_prod(10)
+print(jv.data)
+
+
+# the same thing with method chaining:
+jv = Jarvis([1,2,3,4])
+
+print(jv.train_sum(2).train_prod(10).data)
diff --git a/method_chaining.py b/method_chaining.py
@@ -0,0 +1,51 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# method_chaining.py
+# Jim Bagrow
+# Last Modified: 2016-12-05
+
+"""
+Method chaining (or cascading) is a technique for making many calls to an
+object with less code. Each method should return a reference to the object
+itself (in Python this reference is called `self`). Then, instead of writing:
+    A.method1()
+    A.method2()
+You can write:
+    A.method1().method2()
+This works because A.method1(), while it may perform some internal task,
+returns A itself. So, in a sense, A.method1() is equal to A.
+
+Below is a silly Python example.
+"""
+
+class Jarvis():
+
+    def __init__(self, data):
+        self.data = data
+
+    def train_sum(self, newX):
+        self.data = [x + newX for x in self.data]
+
+        return self # This is what allows chaining
+
+    def train_prod(self, beta):
+        self.data = [x*beta for x in self.data]
+        return self
+
+
+if __name__ == "__main__":
+
+    # initialize the object:
+    jv = Jarvis([1,2,3,4])
+
+    # use its methods 
+    jv.train_sum(2)
+    jv.train_prod(10)
+    print(jv.data)
+
+
+    # the same thing with method chaining:
+    jv = Jarvis([1,2,3,4])
+
+    print(jv.train_sum(2).train_prod(10).data)