C# delegate with pre-set parameters [duplicate]

Question

I need to do something similar with command pattern, but in terms of delegate or something similar.

It should look like this:

private MyFunc Method1() {
    MyFunc func;
    
    /*
        set all parameters to func
    */  
    
    return func;
}

private void Method2()
{
    var funcWithAllParameters = Method1();
    funcWithAllParameters.Invoke();
}

private MyFunc(a lot of parameters) {}

Answer 1

You can do this using a lambda function, which supplies the parameters for and calls MyFunc. The result is an Action delegate, which has the signature void ()

private Action Method1() {
    return () => MyFunc(new Type1(), null);
}

private void Method2()
{
    var funcWithAllParameters = Method1();
    funcWithAllParameters.Invoke();
}

private void MyFunc(Type1 p1, Type2 p2)
{
    //
}

dotnetfiddle

Answer 2

You can put the values into a closure like so:

private Func<TResult> Method1()
     => () =>  MyFunc(/*a lot of parameters*/"param1", 12, ...);

Thus you could load the parameters in the closure and use the Function afterwards:

var func = Method1();
var result = func();

And of course you can also use the function as parameter for other functions:

private TResult SomeOtherMethod(Func<TResult> functionWithSetParameters)
    => functionWithSetParameters();