如何创建在调用中使用其他函数的通用函数。 [英] How do I create a generic function that uses other functions in the call.

问题描述

我正在尝试消除一堆遵循此模式的重复代码：

I am trying to eliminate a bunch of duplicated code that follows this pattern:

protected OdbcConnection Connection { get; set; }
protected  OdbcCommand Command { get; set;}
protected OdbcDataReader Reader { get; set; }

public string BuildQuery (string parm)
{
    string query = string.Empty;
    // build query
    return query;
}

public void ProcessDataFromReader()
{
    // do something with reader
}

public void GetData()
{
    Command.CommandText = BuildQuery("parms");

    using (Reader = Command.ExecuteReader())
    {
        while (Reader.Read())
        {
             ProcessDataFromReader();
        }
    }
}

我想创建一个处理上述方法的通用方法但允许这两个函数可以互换：

* ProcessDataFromReader（）

* BuildQuery（parms）



谢谢



我正在尝试构建一个类似的通用方法：

I want to create a generic method that handles the methodology above but allow the two functions to be interchangable:
* ProcessDataFromReader()
* BuildQuery("parms")

Thanks

I am trying to build a generic method something like:

public void GetData<T>(Func<object[], string> TQuery, Func<T> TRead)
{
    Command.CommandText = (string)TQuery();

    using (Reader = Command.ExecuteReader())
    {
	while (Reader.Read())
	{
	    TRead();
	}
    }
}

所以我可以有多个查询来执行并且能够读取查询的结果，而不必一遍又一遍地写相同的模式。

so I can have several queries to execute and be able to read the results of the queries without having to write the same pattern over and over.

推荐答案

我想我有解决方案：

I think I have the solution:

{
    public class Class1
    {

        protected OdbcConnection Connection { get; set; }
        protected OdbcCommand Command { get; set; }
        protected OdbcDataReader Reader { get; set; }

        public string BuildQuery1(string parm)
        {
            string query = string.Empty;
            // build query
            return query;
        }

        public string BuildQuery2(string parm1, double parm2)
        {
            string query = string.Empty;
            // build query
            return query;
        }

        public List<int> ProcessDataFromReader1()
        {
            // do something with reader
            return new List<int>();
        }

        public List<double> ProcessDataFromReader2()
        {
            // do something with reader
            return new List<double>();
        }

        public void GetGeneric()
        {
            Func<string> query = delegate { return this.BuildQuery1("parms"); };
            Func<List<int>> read = delegate { return this.ProcessDataFromReader1(); };
            GetData(query, read);
        }

        public void GetGeneric()
        {
            Func<string> query = delegate { return this.BuildQuery2("parms", 10d); };
            Func <List<double>> read = delegate { return this.ProcessDataFromReader2(); };
            GetData(query, read);
        }

        public void GetData<T>(Func<string> TQuery, Func<T> TRead)
        {
            Command.CommandText = TQuery();

            using (Reader = Command.ExecuteReader())
            {
                while (Reader.Read())
                {
                    TRead();
                }
            }
        }
    }
}

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