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1 | | -"""http://stackoverflow.com/questions/963965/how-is-this-strategy-pattern-written-in-python-the-sample-in-wikipedia |
2 | | -
|
3 | | -In most of other languages Strategy pattern is implemented via creating some base strategy interface/abstract class and |
4 | | -subclassing it with a number of concrete strategies (as we can see at http://en.wikipedia.org/wiki/Strategy_pattern), |
5 | | -however Python supports higher-order functions and allows us to have only one class and inject functions into it's |
6 | | -instances, as shown in this example. |
| 1 | +# http://stackoverflow.com/questions/963965/how-is-this-strategy-pattern |
| 2 | +# -written-in-python-the-sample-in-wikipedia |
| 3 | +""" |
| 4 | +In most of other languages Strategy pattern is implemented via creating some |
| 5 | +base strategy interface/abstract class and subclassing it with a number of |
| 6 | +concrete strategies (as we can see at |
| 7 | +http://en.wikipedia.org/wiki/Strategy_pattern), however Python supports |
| 8 | +higher-order functions and allows us to have only one class and inject |
| 9 | +functions into it's instances, as shown in this example. |
7 | 10 | """ |
8 | 11 | import types |
9 | 12 |
|
10 | 13 |
|
11 | 14 | class StrategyExample: |
12 | 15 | def __init__(self, func=None): |
13 | | - self.name = 'Strategy Example 0' |
| 16 | + self.name = 'Strategy Example 0' |
14 | 17 | if func is not None: |
15 | | - self.execute = types.MethodType(func, self) |
| 18 | + self.execute = types.MethodType(func, self) |
16 | 19 |
|
17 | | - def execute(self): |
18 | | - print(self.name) |
| 20 | + def execute(self): |
| 21 | + print(self.name) |
19 | 22 |
|
20 | 23 |
|
21 | 24 | def execute_replacement1(self): |
22 | | - print(self.name + ' from execute 1') |
| 25 | + print(self.name + ' from execute 1') |
23 | 26 |
|
24 | 27 |
|
25 | 28 | def execute_replacement2(self): |
26 | | - print(self.name + ' from execute 2') |
| 29 | + print(self.name + ' from execute 2') |
27 | 30 |
|
28 | 31 |
|
29 | 32 | if __name__ == '__main__': |
30 | | - strat0 = StrategyExample() |
| 33 | + strat0 = StrategyExample() |
31 | 34 |
|
32 | 35 | strat1 = StrategyExample(execute_replacement1) |
33 | | - strat1.name = 'Strategy Example 1' |
| 36 | + strat1.name = 'Strategy Example 1' |
34 | 37 |
|
35 | 38 | strat2 = StrategyExample(execute_replacement2) |
36 | 39 | strat2.name = 'Strategy Example 2' |
37 | 40 |
|
38 | 41 | strat0.execute() |
39 | | - strat1.execute() |
| 42 | + strat1.execute() |
40 | 43 | strat2.execute() |
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