Can't pass func arguments within method

Question

I'm trying to pass a Func<TResponse, T1, T2> through to this method. I keep getting a syntax error for "method()" though. It says it needs two arguments which makes sense, but how do I pass it to the method? I've assigned them as T1 and T2.

How can I make this return the TResponse as well?

The way I'm calling it (the func I want to use to call the method).

_service.Count(fileDate (DateTime), cycle int));

What am I doing wrong here?

public TResponse ExecuteAndLog<T1, T2,TResponse>(Guid id, string Name, Func<T1, T2, TResponse> method) where TResponse : class
{
    try
    {
        Log(id, Name);
        TResponse x = method();
        Log(id, Name);
    }
    catch (Exception ex)
    {
        Log(id, Name);
        throw;
    }
}

Voting to close this as a typo because you're just trying to call a method without the required number of parameters. — DavidG, Jul 30 '18 at 23:56

score 3 · Accepted Answer · answered Jul 31 '18 at 00:10

I'm guessing you actually want this....

public TResponse ExecuteAndLog<TResponse>(Guid id, string Name, Func<TResponse> method) where TResponse : class
{
    try
    {
        Log(id, Name);
        TResponse x = method();
        Log(id, Name);
    }
    catch (Exception ex)
    {
        Log(id, Name);
        throw;
    }
}

And you'd call it with

var response = ExecuteAndLog(someGuid, someName, () => _service.Count(fileDate, cycle));

This way you only need one prototype of ExecuteAndLog. If you include the inputs in the Func (as you did in your example), you'd have to pass the arguments through, and you'd need a different version of ExecuteAndLog for each possible service call signature.

Note: Whenever you use a lambda expression this way, be careful of closures.

I don't know why I didn't think of this way from the beginning... I would just add a `return x;` so this compiles, though — Camilo Terevinto, Jul 31 '18 at 00:30

score 2 · Answer 2 · answered Jul 30 '18 at 23:55

2

If method should receive two parameters, you need to pass them:

public TResponse ExecuteAndLog<T1, T2,TResponse>(Guid id, string Name, Func<T1, T2, TResponse> method, T1 arg1, T2 arg2) where TResponse : class
{
    try
    {
        Log(id, Name);
        TResponse x = method(arg1, arg2);
        Log(id, Name);

        return x;
    }
    catch (Exception ex)
    {
        Log(id, Name);
        throw;
    }
}

answered Jul 30 '18 at 23:55

Camilo Terevinto

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That makes heaps of sense! I was getting the format for the method signature wrong and got confused. Thank you. – magna_nz Jul 30 '18 at 23:56
How would I call this function now using _service.Count(fileDate (DateTime), cycle int))? – magna_nz Jul 31 '18 at 00:08
@magna_nz You would call it using `ExecuteAndLog(someGuid, someString, _service.Count, fileDate, cycle)` – Camilo Terevinto Jul 31 '18 at 00:29

Can't pass func arguments within method

2 Answers2