add closure.py to demo closure in python

smilejay · smilejay · commit 92c00a692e20 · 2014-08-26T23:19:20.000+08:00
diff --git a/py2014/closure.py b/py2014/closure.py
@@ -0,0 +1,64 @@
+#!/usr/bin/env python
+
+
+def closure1():
+    flist = []
+
+    for i in xrange(3):
+        def func(x):
+            return x * i
+        flist.append(func)
+
+    for f in flist:
+        print f(2)
+
+
+def closure2(msg):
+    def printer():
+        print msg
+    return printer
+
+
+def not_closure2(msg):
+    def printer(msg=msg):
+        print msg
+    return printer
+
+
+def generate_power_func(n):
+    def nth_power(x):
+        return x ** n
+    return nth_power
+
+
+def outer():
+    d = {'y': 0}
+
+    def inner():
+        d['y'] += 1
+        return d['y']
+    return inner
+
+
+def foo():
+    a = [1, ]
+
+    def bar():
+        a[0] = a[0] + 1
+        return a[0]
+    return bar
+
+
+if __name__ == '__main__':
+    closure1()
+    printer = closure2('Foo!')
+    printer()
+    printer = not_closure2('Foo!')
+    printer()
+    raised_to_4 = generate_power_func(4)
+    del generate_power_func
+    print raised_to_4(2)
+    outer = outer()
+    print outer()
+    foo = foo()
+    print foo()
