Use variable in place of function name

Question

I\'m using the following right now:

foreach (string file in files) {
    switch (filetype.Value) {
        case \"ReadFile\":
            ReadFile(file);
                


        

Answer 1

You can use a delegate:

Action<string> action;
switch (filetype.Value) {
  case "ReadFile":
    action = ReadFile;
    break;
  case "ReadMSOfficeWordFile":
    action = ReadMSOfficeWordFile;
    break;
  case "ReadMSOfficeExcelFile":
    action = ReadMSOfficeExcelFile;
    break;
  case "ReadPDFFile":
    action = ReadPDFFile;
    break;
  default: 
    throw new NotImplementedException("Unhandled file type '"+filetype.Value+"'.");
}
foreach (string file in files) {
  action(file);
}

Answer 2

If you're looking for a way to avoid the explicit mapping of method names to string values you could use reflection to do dynamic method invocation (this assumes filetype.Value is of type String)

String method_name = String.Empty;
foreach (string file in files) {
    method_name = filetype.Value;
    System.Reflection.MethodInfo method = this.GetType().GetMethod(method_name);
    method.Invoke(this, new object[]{file});
}

Answer 3

You can do it with some preparation using delegates, like this:

private static readonly IDictionary<string,Action<string>> actionByType =
    new Dictionary<string,Action<string>> {
        {"ReadFile", ReadFile}
    ,   {"ReadMSOfficeWordFile", ReadMSOfficeWordFile}
    ,   {"ReadMSOfficeExcelFile", ReadMSOfficeExcelFile}
    ,   {"ReadPDFFile", ReadPDFFile}
    };

When it is time to call your action, do it as follows:

actionByType[actionName](file);

Answer 4

You could also use reflection (if you're okay with the different overhead that can bring) Check this solution

Hope that helped

Answer 5

You could keep a Dictionary of delegates, as the simplest way:

Dictionary<string, Action<string>> fileReaders = new Dictionary<string, Action<string>>() {
    {"ReadFile", ReadFile},
    {"ReadOfficeWordFile", ReadOfficeWordFile},
    {"ReadOfficeExcelFile", ReadOfficeExcelFile},
    {"ReadPDFFile", ReadPDFFile}
};

Then call it like this:

fileReaders[fileType.Value](file);

Depending on what your methods return, you may have to change the type of the delegate (Action<string> means void something(string someparam) as a method signature, for example) as well.

Answer 6

I believe what you're looking for will need some refactoring of your code.

All of your "cases" (TextFile, MSOfficeWordFile, MSOfficeExcelFile, PdfFile) should be their own classes which implement a single interface.

Your interface should be named something like "IReadableFile" and specify a method named "ReadFile()".

Each class should have their own implementation of "ReadFile()"

Example:

public interface IReadableFile
{
    void ReadFile();
}

---

public class MSOfficeWordFile : IReadableFile
{
    public void ReadFile()
    {
        ReadMSOfficeWordFile(file);
    }
} 

---

foreach(IReadableFile file in files)
    file.ReadFile();

Code may contain some mistakes, but I hope you get the idea.