python设计模式第十七天【解释器模式】

1.应用场景

（1）解释预先定义的文法

2.代码实现

#!/usr/bin/env python
#!_*_ coding:UTF-8 _*_

from abc import ABCMeta, abstractmethod

class Context(object):

    def __init__(self, input):
        self.__input = input

    def getInput(self):
        return self.__input

    def setInput(self, input):
        self.__input = input

    def getOutput(self):
        return self.__output

    def setOutput(self, output):
        self.__output = output

class Expression(object):

    __metaclass__ = ABCMeta

    @abstractmethod
    def interpret(self, context):
        pass

class PlusExpression(Expression):

    def interpret(self, context):
        input = context.getInput()
        input = int(input)
        output = input + 1
        context.setOutput(output)

class SubExpression(Expression):

    def interpret(self, context):
        input = context.getInput()
        input  = int(input)
        output = input - 1
        context.setOutput(output)

if __name__ == "__main__":
    context = Context(")

    expression = PlusExpression()
    expression.interpret(context)
    print context.getOutput()

    expression = SubExpression()
    expression.interpret(context)
    print context.getOutput()

结果：

/Users/liudaoqiang/PycharmProjects/numpy/venv/bin/python /Users/liudaoqiang/Project/python_project/day17_interpret/interpret_test.py
6
4

Process finished with exit code 0