使用 Action 字典而不是 switch 语句

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问题描述

I'm just reviewing some of my old code (have some spare time), and I noticed a rather lengthy switch statement. Due to gaining new knowledge, I have since refactored it in the following form:

private Dictionary<string, Action> createView
    {
        get
        {
            return new Dictionary<string, Action>()
            {
                {"Standard", CreateStudySummaryView},
                {"By Group", CreateStudySummaryByGroupView},
                {"By Group/Time", CreateViewGroupByHour}
            };
        }
    }

Would you consider this good practise, or is this simply a case of being superflous and unneccessary? I'm keen to ensure new techniques that I learn, are not being clever just for the sake of it, and that they actually add benefit to the code.

Thanks.

解决方案

Long switch statements are a classic bad smell, and are always a target for refactoring.

The "standard" step to perform here is Replace Conditional with Polymorphism. This was one of the steps listed in Martin Fowler's book Refactoring (published 11 years ago in 1999).

Now that it's so easy to treat functions like objects (eg with Action) this might be just as good a solution.

And no, I don't think you're being clever for the sake of it. If I wanted to add another option in the future, I can easily see what needs to be done.

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使用 Action 字典而不是 switch 语句

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