更换为大的开关？ [英] Replacement for big switch?

问题描述

我有一个名为ReportController.aspx，其目的是实例基于查询字符串参数的报表（班）页

I have a page named "ReportController.aspx" whose purpose is to instantiate a report (class) based on query string parameters

        switch (Request.QueryString["Report"])
        {                
            case "ReportA":
                CreateReportAReport("ReportA's Title");
                break;
            case "ReportB":
                CreateReportBReport("ReportB's Title");
                break;                
            case "ReportC":
                CreateReportCReport("ReportC's Title");
                break;
            case "ReportD":
                CreateReportDReport("ReportD's Title");
                break;
                ...

基本上，需要新的报告中的每个时间会有增加的情况下，加入的方法的此开销。这个switch语句可以得到非常非常长。我读的是可以用字典来一个报表映射到？如何使用字典这个样子（假设这是一个更好的方法）。

Basically, each time a new report is needed there will be this overhead of adding a case and adding a method. This switch statement could get very very long. I read that is is possible to use a Dictionary to map a Report to ?. How would this look using a Dictionary (assuming this is a better way).

此外， CreateReportXReport 方法主要通过一堆额外的查询字符串值报告类的构造函数（每一个报表类有不同的构造函数）。

Also, CreateReportXReport method basically passes a bunch of additional QueryString values to the report class's constructor (each report class has a different constructor).

推荐答案

假设所有报告落实的iReport ，您可以使用函数功能：LT做到这一点; iReport的＆GT; ，像这样的：

Assuming that all reports implement IReport, you can do it using Func<IReport>, like this:

IDictionary<string,Func<IReport>> dictToReport = new Dictionary {
    {"ReportA", () => CreateReportAReport("ReportA's Title") }
,   {"ReportB", () => CreateReportBReport("ReportB's Title") }
,   ...
};

您可以再与该code更换开关：

You can then replace the switch with this code:

var myReport = dictToReport[Request.QueryString["Report"]]();

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