如何从另一个func返回func? [英] How to return in func FROM another func?

问题描述

我想在调用/退出子函数 apiResponse()

I want to end execution in parent func apiEndpoint() upon calling/exiting in a child func apiResponse()

func apiEndpoint() {
    if false {
        apiResponse("error")
        // I want apiResponse() call to return (end execution) in parent func
        // so next apiResponse("all good") wont be executed
    }

    apiResponse("all good")
}

func apiResponse(message string) {
    // returns message to user via JSON
}

推荐答案

一个函数或方法不能从它被调用的地方控制执行(控制流).您甚至不能保证它是从您的函数中调用的，例如可能会调用它来初始化一个全局变量.

A function or method cannot control the execution (control flow) from where it was called from. You don't even have guarantee it was called from your function, it may be called to initialize a global variable for example.

话虽如此，结束执行并返回是调用者的责任，明确地使用 return 语句.

That being said it is the responsibility of the caller to end the execution and return, explicitly with the return statement.

如果例子和你的一样简单，你可以使用 if-else 来避免 return 语句:

If the example is as simple as yours, you can avoid the return statement though by using if-else:

func apiEndpoint() {
    if someCondition {
        apiResponse("error")
    } else {
        apiResponse("all good")
    }
}

此外，如果函数具有返回值并且 apiResponse() 将返回一个值，该值将是调用者的返回值，您可以在一个中执行 return行，例如

Also if the functions have return values and the apiResponse() would return a value that would be the return value of the caller, you can do the return in one line, e.g.

func apiEndpoint() int {
    if someCondition {
        return apiResponse("error")
    }

    return apiResponse("all good")
}

func apiResponse(message string) int {
    return 1 // Return an int
}

注意:

只是为了完整性，但不是您的情况的解决方案:如果被调用函数将 panic()，则调用者函数中的执行将停止并且恐慌序列将在调用层次结构中上升(在运行 defer 函数之后，如果它们不调用 recover()).恐慌恢复是为其他目的而设计的，而不是作为被调用函数停止调用函数执行的手段.

Just for completeness but not as a solution in your case: if the callee function would panic(), the execution in the caller function would stop and the panicing sequence would go up in the call hierarchy (after running defer functions, and if they don't call recover()). Panic-recover is designed for something else and not as a mean for callee functions to stop executions in caller functions.

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