Write Delegates without messing up the code

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Hi,

I am writing delegates as like this.

C#

delegate void MyMethod(string arg1, string arg2);
MyMethod mm;

I don't know why it needs two lines to declare a single delegate. If my class has 20 delegates, I need to write 40 line of code.
Can anybody tell me a way to write this in one line of code ?
Thanks in Advance.

Posted 22-Jun-14 20:06pm

Yesudass Moses

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Thomas Daniels 23-Jun-14 2:19am

Why do you need 20 delegates?

Sergey Alexandrovich Kryukov 23-Jun-14 2:31am

Reasonable question. I can imagine 20 delegate instances (or, more likely, indefinitely big number of them, created on the fly), but why 20 different delegate types? However, I know at least one case what doing so is very wise: unification of some available unmanaged API for more than one instruction set platform under a single "Any CPU" assembly. Could you beat that?
—SA

Sergey Alexandrovich Kryukov 23-Jun-14 2:33am

OP answered below...
—SA

Thomas Daniels 23-Jun-14 2:36am

Ok, thanks for notifying.

Yesudass Moses 23-Jun-14 2:31am

I have a class that works in a thread, I need to trigger the functions(events) inside the main form if needed. Moreover I dont want to deal with form properties directly from the class, instead calling the function, that updates the form..

Sergey Alexandrovich Kryukov 23-Jun-14 2:33am

I does not sound like a good excuse for all those delegates. Do you know anonymous methods?
—SA

2 solutions

Solution 1

The first line is the definition of the delegate (you can compare it to a class, struct or enum definition).
The second line declares a variable which has your delegate as type.
These are not the same things. You cannot mix them in a single statement.
Cheers.

Posted 22-Jun-14 20:20pm

phil.o

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Sergey Alexandrovich Kryukov 23-Jun-14 2:24am

Not quite. Please see my answer.
—SA

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Sergey Alexandrovich Kryukov · Accepted Answer · 2014-06-22T20:23:00

Chasing minimal number of lines is just silly. You should try to write the number of lines promoting better readability, never repeating the same code, and so on.

However, there is absolutely no way to write those delegate types like the one you wrote. You can solve such problems using generics. You don't even have to define generic types or methods: several definitions in .NET BCL already cover some 99% of practically important cases including yours. This is what you can do:

C#

System.Action<string, string> mm;

That's not all. You don't even need to write a separate (named) method if you want immediately initialize mm> with some delegate instance. Here is what you can do, for example:

C#

System.Action<string, string> mm = new System.Action<string, string>((s1, s2) => {
    System.Console.WriteLine(@"First argument: ""{0}""; second argument:""{1}""", s1, s2); // or anything else
});

To understand how it all works, read on the following topics: 1) generics, 2) anonymous methods; 3) lambda expressions and methods; 4) as a bonus: closures.

By the way, I would advise to read some language and .NET manual from the beginning to the end before writing anything serious (beyond learning exercises) and trying to improve something. First, you need to know what is already available.

—SA