How to 'parse' input string and call target function?

Question

i'm developing a math/statistical software. I would like that my customer can write something like :

Function1(value)

Then, depending on the name of the function, call my internal software function. This seems a 'parser' right?

At the moment i'm thinking to solve it with a code like this:

    switch(my_parsed_function_string) {
       case "function1":
          result = function1(value);
       case "function2": 
          result = function2(value);
    ...
    ...
    }

Is there a more elegant way ? A way where a string contained the 'function' name can be lunched without extra developer work ?

Thank you in advance

Anton Gogolev · Accepted Answer · 2011-09-16 13:14:48Z

2

Yes, there is. It's called IDictionary. More specifically, in your case it will be more like IDictionary<string, Func<double>>. Thus, your code turns into

var functions = new Dictionary<string, Func<double>>();
var act = functions[my_parsed_function_string].Invoke(arg);

answered Sep 16, 2011 at 13:14

Anton Gogolev

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npclaudiu · Accepted Answer · 2011-09-19 13:10:49Z

1

You can use the Command Pattern. For example:

interface ICommand
{
    void Execute();    
}

class Function1Command : ICommand
{
    public void Execute()
    {
        // ...
    }
}

class Function2Command : ICommand
{
    public void Execute()
    {
        // ...
    }
}

// Bind commands
IDictionary<string, ICommand> commands = new Dictionary<string, ICommand>();
commands["Function1"] = new Function1Command(); // function 1
commands["Function2"] = new Function2Command(); // function 2
// ...

Then you can call your functions like this:

ICommand command = commands[parsedFunctionName] as ICommand;
if(command != null)
{
    command.Execute();
}

edited Sep 19, 2011 at 13:10

answered Sep 16, 2011 at 13:18

npclaudiu

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Comments

Thilak Nathen · Accepted Answer · 2011-09-16 13:13:04Z

-2

You could declare all the functions in a single object, then reflect on it to get the method names?

answered Sep 16, 2011 at 13:13

Thilak Nathen

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