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# http://stackoverflow.com/questions/963965/how-is-this-strategy-pattern
# -written-in-python-the-sample-in-wikipedia
"""
In most of other languages Strategy pattern is implemented via creating some
base strategy interface/abstract class and subclassing it with a number of
concrete strategies (as we can see at
http://en.wikipedia.org/wiki/Strategy_pattern), however Python supports
higher-order functions and allows us to have only one class and inject
functions into it's instances, as shown in this example.
"""
import types
class StrategyExample:
def __init__(self, func=None):
self.name = 'Strategy Example 0'
if func is not None:
self.execute = types.MethodType(func, self)
def execute(self):
print(self.name)
def execute_replacement1(self):
print(self.name + ' from execute 1')
def execute_replacement2(self):
print(self.name + ' from execute 2')
if __name__ == '__main__':
strat0 = StrategyExample()
strat1 = StrategyExample(execute_replacement1)
strat1.name = 'Strategy Example 1'
strat2 = StrategyExample(execute_replacement2)
strat2.name = 'Strategy Example 2'
strat0.execute()
strat1.execute()
strat2.execute()
### OUTPUT ###
# Strategy Example 0
# Strategy Example 1 from execute 1
# Strategy Example 2 from execute 2
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