属性 getter 中的逻辑 [英] Logic in property getters

问题描述

对于属性 getter 来说，多少逻辑太多了?例如，我的代码如下所示:

How much logic is too much for a property getter? For example, I have code which looks like this:

        public double value
        {
            get
            {
                if (condition1
                    || condition2
                    || condition3
                    || condition4)
                {
                    _value = anotherValue;
                }
                return _value;
            }
        }

我读过各种帖子，说属性中的代码不应该很昂贵.但是昂贵"这个词对我来说有点含糊.

I have read various posts that say the code inside properties should not be expensive. But the term 'expensive' is a bit vague for me.

推荐答案

一般来说，在 OOP 中，getter(setter)应该是一个微不足道的操作.您在上面发布的内容是微不足道的，取决于实际情况.

Generally speaking, in OOP a getter (setters too) should be a trivial operation. What you've posted above is trivial, depending on what the conditions actually are.

您提到昂贵"对您来说是一个模糊的术语.一个计算成本高的操作意味着它需要很长时间才能完成(通常是因为它必须完成大量的计算——这过于简单化了，但这是一个不错的近似值).例如，考虑:

You mentioned that "expensive" is a vague term to you. An operation being computationally expensive means that it will take a long time to complete (usually because it has to complete a lot of computations -- that's an oversimplification, but a decent approximation). For instance, consider:

if (a == 5
    || b == true
    || c == "FOO!"
    || d == 3.14159)
{
    _value = anotherValue;
}
return _value;

在这个例子中，条件是微不足道的，你的程序将几乎瞬间处理这个块.另一方面:

In this example, the conditions are trivial, and your program will crunch through this block near-instantaneously. On the other hand:

if (some_slow_function())
{
    _value = anotherValue;
}
return _value;

假设 some_slow_function 实际上运行很慢，这个块将需要很长时间才能返回 _value，使其不再微不足道.如果这个 getter 被频繁调用，some_slow_function 也会被频繁调用，导致它成为你程序的瓶颈并导致它运行缓慢.

Assuming some_slow_function does actually run slowly, this block will take a long time to return _value, making it no longer trivial. If this getter is called often, some_slow_function will be called often as well, causing it to bottleneck your program and cause it to run slowly.

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