Using 'this' keyword in constructor

Question

What is the difference b/w the following two codes. What is the use of using 'this' keyword in the constructor.

Ex 1:

public Product(string name){
this.Name = name;
}

Ex 2:

public Product(string name){
Name = name;
}

I know this refers to the calling object. Just I couldn't able to get the difference?

can some one please explain?

"To qualify members hidden by similar names". It is explained here: http://msdn.microsoft.com/en-gb/library/dk1507sz(v=vs.90).aspx — Saturnix, Sep 06 '13 at 09:05

score 6 · Accepted Answer · answered Nov 19 '10 at 17:37

6

Example 1 uses an explicit reference to this. This is not really needed as there's no ambiguity in this case. If the parameter was called Name instead, the explicit this would be required to resolve the ambiguity.

answered Nov 19 '10 at 17:37

Brian Rasmussen

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Will Marcouiller · Answer 2 · 2010-11-19T18:20:54.753

4

It is absolutely optional in the example you provide.

Mainly, it implicitely tells the user that the member that is worked with is part of the current class object.

One practice was to differentiate parameters from members or fields like the following:

public class Customer {
    private string name;

    public Customer(string name) {
        this.name = name;
    } 
}

For readability's sake, one would put this in front of the name field to make it clear that the value of the name parameter is assigned to the this class' name field.

In such situation, it is necessery, as both the constructor parameter and the field have the same name. Otherwise, if they were different variable names, the this keyword would be optional.

edited Nov 19 '10 at 18:20

answered Nov 19 '10 at 17:38

Will Marcouiller

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In the example you've given here, "this" is *not* optional - the code has different meaning with and without the "this". – razlebe Nov 19 '10 at 18:01
Second for "this" not being optional in this particular example. – Timothy Lee Russell Nov 19 '10 at 18:13
I expose a situation where it is not optional, indeed, and that is what I wanted to tell the OP. With different names (field and constructor parameter), `this` becomes optional. I don't get the downvotes... – Will Marcouiller Nov 19 '10 at 18:23
I took off my down vote. Your edit makes your point much clearer. – Timothy Lee Russell Nov 19 '10 at 18:34
I agree, and have removed my downvote too. Thanks for editing. – razlebe Nov 19 '10 at 19:00

score 3 · Answer 3 · answered Nov 19 '10 at 17:40

In that case, there's no difference. The more common reason for being explicit is something like this:

public Product(string name){
    this.name = name;
}

At that point the this is absolutely required, otherwise it would be a no-op assignment from the parameter to itself (which would raise a warning, IIRC).

score 2 · Answer 4 · answered Nov 19 '10 at 17:37

2

In terms of emitted IL absolutely no difference. It's just for readability. When you use this you are more explicit.

answered Nov 19 '10 at 17:37

Darin Dimitrov

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score 1 · Answer 5 · answered Nov 19 '10 at 17:39

1

this.Name is more explicit than just Name. Using this makes it more obvious as to what the code is doing; but in this case the compiler will interpret them the same way.

answered Nov 19 '10 at 17:39

Donut

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score 1 · Answer 6 · answered Nov 19 '10 at 17:54

I disagree with other here who say using "this" is more explicit. It is most definitely not. In the examples you gave, the property "Name" is as explicit as it gets. If we had another keyword that had more letters than "this" it wouldn't be more explicit.

Name

is no less explicit than

this.Name

which is also no less explicit than the following nonsense

thisIsNotAKeyWordButItMeansThis.Name

score 0 · Answer 7 · answered Nov 19 '10 at 17:48

It is a matter of style. Like the others have said, there is no difference in the IL. Personally, I like to see the this. prefix used whenever accessing members of the class. In fact, the default StyleCop rules require it. It just makes it clear where the member is coming from.

Using 'this' keyword in constructor

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