c#速记，如果不为null，则赋值 [英] c# shorthand for if not null then assign value

问题描述

现在C#中是否有任何速记可以削减以下代码:

Is there any shorthand in c# now that will cutdown the following code:

var testVar1 = checkObject();
if (testVar1 != null)
{
      testVar2 = testVar1;
}

在这种情况下，如果CheckObject()结果中的testVar1不为null，则只想分配testVar2(testVar2具有将触发代码的setter).试图思考如何使用null合并的东西，但没有真正解决问题.

In this situation only want to assign testVar2 if testVar1 is not null from the CheckObject() result (testVar2 has a setter that will fire off code). Was trying to think how could use the null coalesce stuff but not really working out.

添加到此testVar2的代码将在其设置程序上触发，因此，如果值为null，则不要将testVar2设置为任何值.

Adding on to this testVar2 has code on it's setter to fire, so do not want testVar2 being set to anything if the value is null.

    public MyObj testVar2
    {
        get { return _testVar2; }
        set
        {
            _testVar2 = value;
            RunSomeCode();                
        }
    }

推荐答案

有几个！

三元运算符:

testvar2 = testVar1 != null ? testvar1 : testvar2;

逻辑将完全相同.

或者，正如您所评论的，您可以使用空合并运算符:

Or, as commented you can use the null coalescing operator:

testVar2 = testVar1 ?? testVar2

(尽管现在也有评论)

或第三个选项:编写一次方法，然后按自己的意愿使用它:

Or a third option: Write a method once and use it how you like:

public static class CheckIt
{
    public static void SetWhenNotNull(string mightBeNull,ref string notNullable)
    {
        if (mightBeNull != null)
        {
            notNullable = mightBeNull;
        }
    }
}  

并命名为:

CheckIt.SetWhenNotNull(test1, ref test2);

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