Data commit

Task/Call-a-function/Python/call-a-function.py

@@ -0,0 +1,70 @@
+def no_args():
+    pass
+# call
+no_args()
+
+def fixed_args(x, y):
+    print('x=%r, y=%r' % (x, y))
+# call
+fixed_args(1, 2)        # x=1, y=2
+
+## Can also called them using the parameter names, in either order:
+fixed_args(y=2, x=1)
+
+## Can also "apply" fixed_args() to a sequence:
+myargs=(1,2) # tuple
+fixed_args(*myargs)
+
+def opt_args(x=1):
+    print(x)
+# calls
+opt_args()              # 1
+opt_args(3.141)         # 3.141
+
+def var_args(*v):
+    print(v)
+# calls	
+var_args(1, 2, 3)       # (1, 2, 3)
+var_args(1, (2,3))      # (1, (2, 3))
+var_args()              # ()
+
+## Named arguments
+fixed_args(y=2, x=1)    # x=1, y=2
+
+## As a statement
+if 1:
+    no_args()
+
+## First-class within an expression
+assert no_args() is None
+
+def return_something():
+    return 1
+x = return_something()
+
+def is_builtin(x):
+	print(x.__name__ in dir(__builtins__))
+# calls
+is_builtin(pow)         # True
+is_builtin(is_builtin)  # False
+
+# Very liberal function definition
+
+def takes_anything(*args, **kwargs):
+    for each in args:
+        print(each)
+    for key, value in sorted(kwargs.items()):
+        print("%s:%s" % (key, value))
+    # Passing those to another, wrapped, function:
+    wrapped_fn(*args, **kwargs)
+    # (Function being wrapped can have any parameter list
+    # ... that doesn't have to match this prototype)
+
+## A subroutine is merely a function that has no explicit
+## return statement and will return None.
+
+## Python uses "Call by Object Reference".
+## See, for example, http://www.python-course.eu/passing_arguments.php
+
+## For partial function application see:
+##   http://rosettacode.org/wiki/Partial_function_application#Python