"""http://ginstrom.com/scribbles/2007/10/08/design-patterns-python-style/

An example of the Template pattern in Python"""

ingredients = "spam eggs apple"

line = '-' * 10

# Skeletons

def iter_elements(getter, action):

"""Template skeleton that iterates items"""

for element in getter():

action(element)

print(line)

def rev_elements(getter, action):

"""Template skeleton that iterates items in reverse order"""

for element in getter()[::-1]:

action(element)

print(line)

# Getters

def get_list():

return ingredients.split()

def get_lists():

return [list(x) for x in ingredients.split()]

# Actions

def print_item(item):

print(item)

def reverse_item(item):

print(item[::-1])

# Makes templates

def make_template(skeleton, getter, action):

"""Instantiate a template method with getter and action"""

def template():

skeleton(getter, action)

return template

# Create our template functions

templates = [make_template(s, g, a)

for g in (get_list, get_lists)

for a in (print_item, reverse_item)

for s in (iter_elements, rev_elements)]

# Execute them

for template in templates:

template()

### OUTPUT ###

# spam

# ----------

# eggs

# ----------

# apple

# ----------

# apple

# ----------

# eggs

# ----------

# spam

# ----------

# maps

# ----------

# sgge

# ----------

# elppa

# ----------

# elppa

# ----------

# sgge

# ----------

# maps

# ----------

# ['s', 'p', 'a', 'm']

# ----------

# ['e', 'g', 'g', 's']

# ----------

# ['a', 'p', 'p', 'l', 'e']

# ----------

# ['a', 'p', 'p', 'l', 'e']

# ----------

# ['e', 'g', 'g', 's']

# ----------

# ['s', 'p', 'a', 'm']

# ----------

# ['m', 'a', 'p', 's']

# ----------

# ['s', 'g', 'g', 'e']

# ----------

# ['e', 'l', 'p', 'p', 'a']

# ----------

# ['e', 'l', 'p', 'p', 'a']

# ----------

# ['s', 'g', 'g', 'e']

# ----------

# ['m', 'a', 'p', 's']

# ----------