How can I prevent repetition of a code block ending in return?

Question

I have a block of code which is used multiple times in multiple class methods. I would like to make it into a separate function, but the code block in question is an if statement with a return, e.g.

private void method() {

    //..

    if (condition) {

            //..

        return;
    }

    //..
}

The problem is that if I pull this out into a separate function, the return applies only to that function itself, and no longer to the class methods in question. What is the best way to deal with this situation?

Answer 1

A good solution is to extract the condition code to a new method that returns a bool and handle this in every method. The code might look a little like this:

private bool CheckCondition()
{
    if (!condition)  // Please recognize the NOT for this condition.
    {
        return true;
    }

    // .. your code from if statement
    return false;    
}

private void Method()
{
    if (!this.CheckCondition())
    {
        return;
    }

    // ...
}

For completeness - there is another way but I would not recommend that:

private void WithCondition(Action action)
{
    if (condition)
    {
        // ..

        return;
    }

    action();
}

private void Method()
{
    void Body()
    {
        // your old method body code after your condition here
    }

    this.WithCondition(Body);
}

But that looks weird. There are use cases for local functions like factory methods e.g. for non-blocking or some event handlers. But your case is not a common use case for that.