Python可链接类方法 [英] Python chainable class methods

问题描述

我要执行以下操作:

pattern = cl().a().b("test").c()

其中 cl 是一个类，而 a，b，c 是类方法.

where cl is a class and a, b, c are class methods.

在那之后，我需要调用 pattern.to_string ，它应该输出一个已形成的字符串.每个方法都返回一个字符串.

After that I need to call pattern.to_string and it should output a string that was formed. Each method returns a string.

现在如何实现以上目标?将方法输出附加到列表?可链接函数呢?如果我以正常方式编写该类，则以上操作将无效.

Now how can I achieve the above? Append the method output to a list? What about the chainable function? If I wrote the class the normal way, the above won't work.

谢谢.

推荐答案

在每个方法的末尾返回类实例，并将中间结果存储在类变量中:

Return the class instance at the end of each method and store the intermediate results in a class variable:

class MyClass:
    result = None

    def a(self):
        # do things and store in self.result
        self.result = ...
        return self

    def b(self, value):
        # do things and store in self.result
        self.result = ...
        return self

这允许您根据需要链接方法: cl().a().b("test").c().

This allows you to chain the methods as desired: cl().a().b("test").c().

然后您可以通过查看 instance.result 的值来获得结果.

You can then obtain the result by looking at the value of instance.result.

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