Generic class implicit T

Question

I have a generic Command of type ICommand:

class SimpleCommand<T> : ICommand
{
    public SimpleCommand(Action<T> execute, Predicate<T> canExecute = null)
    {
        if (execute == null)
            throw new ArgumentNullException("execute");

        _execute = execute;
        _canExecute = canExecute;
    }
    /*
        All the other stuff...
    */
}

Used like this:

ICommand command = new SimpleCommand<string>(MyMethod);

private void MyMethod(string arg) { ... }

When using i would like the compiler to automaticly pick up the T from the Action passed, so i can just write like tihs:

ICommand command = new SimpleCommand(MyMethod);

However if i write like so, i get an compiler error. Is it possible to make the compiler pick up the T class from the Method parameter type ?

Incorrect number of type parameters in reference to class 'SimpleCommand' — Anders, Jun 23 '14 at 12:47

score 2 · Accepted Answer · answered Jun 23 '14 at 12:48

2

You could implement static Create method.

public static class Command
{
    public static SimpleCommand<T> Create<T>(Action<T> execute, Predicate<T> canExecute = null)
    {
        return new SimpleCommand<T>(execute, canExecute);
    }
}

That should allow compiler to pick up the generic argument when called like:

ICommand command = Command.Create(MyMethod);

answered Jun 23 '14 at 12:48

Euphoric

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It should be `...= Command.Create...`, not `...= new Command.Create...` – sloth Jun 23 '14 at 12:50

Moho · Answer 2 · 2014-06-23T12:54:32.447

2

Not for a constructor, but you could implement the factory pattern which could instantiate the correct type based on the argument

edited Jun 23 '14 at 12:54

answered Jun 23 '14 at 12:48

Moho

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Generic class implicit T

2 Answers2