对“Action"委托和 lambda 表达式的困惑
问题描述
我不明白为什么 TestDelegateStatement3
有效但 TestDelegateStatement1
失败.在这两种情况下,Action
都提供了一个采用零参数的方法.他们可能调用一个采用单个参数(aString
)的方法,但这应该是无关紧要的.他们不带参数.这只是不可能与 lamda 表达式有关,还是我做错了什么?
I don't understand why TestDelegateStatement3
works but TestDelegateStatement1
fails. In both cases, Action
is supplied with a method that takes zero parameters. They may call a method that takes a single parameter (aString
), but that should be irrelevant. They don't take a parameter. Is this just not possible to do with lamda expressions, or am I doing something wrong?
推荐答案
如你所说,Action 不带任何参数.如果你这样做:
As you said, Action doesn't take any parameters. If you do this:
这里是你实际执行的方法,所以那不是方法参数.
You actually execute the method here, so that is not a method parameter.
如果你这样做:
你告诉它你的方法有一个名为 param
的参数,而 Action 没有.
you tell it that your method takes a parameter called param
, which Action does not.
所以正确的做法是:
或更紧凑:
空括号用于表示 lambda 不带任何参数.
the empty brackets are used to indicate the lambda doesn't take any parameters.
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