What is a property?

[Peter Kirk]

Hi there,

can someone tell me what exactly a "property" is in a C# class? As far as I
can see it is "two methods" - ie a getter and a setter for an instance
variable.

What is the difference between these:

public string InstanceStringV ariable()
{
get { return _instanceString Variable; }
set { _instanceString Variable = value; }
}

and

public string getInstanceStri ngVariable
{
return _instanceString Variable;
}

public void setInstanceStri ngVariable(stri ng stringVariable)
{
_instanceString Variable = stringVariable;
}

Thanks,
Peter

[KH]

I tend to think of properties as adjectives and methods as verbs - properties
describe the object - color, name, size - whereas methods are actions -
Read(), Write(), Dispose(), Jump(), etc.

It should probably be noted that properties get turned into methods by the
compiler. So for example if you had a property:

object MyProperty
{
get { throw new Exception(); }
}

and you called .MyProperty, it would be referred to in the call stack as:

get_MyProperty( object value)

"Jon Shemitz" wrote:

Peter Kirk wrote:

can someone tell me what exactly a "property" is in a C# class? As far as I
can see it is "two methods" - ie a getter and a setter for an instance
variable.

Well, "one or two methods" - you have can have a get without a set (or
a set without a get, though the semantics are pretty weird, there).

What is the difference between these:

public string InstanceStringV ariable()
{
get { return _instanceString Variable; }
set { _instanceString Variable = value; }
}

and

public string getInstanceStri ngVariable
{
return _instanceString Variable;
}

public void setInstanceStri ngVariable(stri ng stringVariable)
{
_instanceString Variable = stringVariable;
}

First, as a number of people have pointed out, a property is a lot
easier to read.

if (This.Bool)

vs

if (this.getBool() )

and the like.

Second, property methods are linked. Declare a property abstract, or
virtual, or static, and both methods are abstract, or virtual, or
static. It would be hard (impossible?) to enforce this linkage with a
get/set convention.

Third, properties ease maintenance / allow optimization. A member
might be a field, because setting it has no side-effects, and you want
to allow fast read/write. As your requirements change, you can easily
change the field to a property without rewriting all the client code.

--

www.midnightbeach.com

[Howard Swope]

Peter:

There are a million different ways to skin a cat. The fact that you have
notion of a getter and a setter (as we all do) is an indication that it
might as well be added as a language feature and fully supported.

I think also that properties are good for thinking in terms of objects. When
I envision systems, my first level of thought is objects consisting of
events, methods, and properties (EMP). Objects of this nature form
relationships with other objects to perform work and provide services.
Properties allow an object to present a public face to the system.
"Peter Kirk" <[e-mail]> wrote in message
news:uy******** ******@TK2MSFTN GP14.phx.gbl...

Hi there,

can someone tell me what exactly a "property" is in a C# class? As far as
I can see it is "two methods" - ie a getter and a setter for an instance
variable.

What is the difference between these:

public string InstanceStringV ariable()
{
get { return _instanceString Variable; }
set { _instanceString Variable = value; }
}

and

public string getInstanceStri ngVariable
{
return _instanceString Variable;
}

public void setInstanceStri ngVariable(stri ng stringVariable)
{
_instanceString Variable = stringVariable;
}

Thanks,
Peter

[Steve Walker]

In message <uH************ **@TK2MSFTNGP10 .phx.gbl>, Christof Nordiek
<[e-mail] > writes

Hi Peter,

It is also possible via getter and setter methods. What exact benefit does
a "property" give us over getter and setter methods?

Simply look at this Example and decide yourselve, wich is more readable:

oldText = control.get_Tex t();
control.get_Te xt(newText);

vs.

oldText = control.Text;
constrol.Tex t = newText;

Or

position.X++;

versus

position.set_X( position.get_X( )+1);

--
Steve Walker

[Peter Kirk]

"Peter Kirk" <[e-mail]> skrev i en meddelelse
news:uy******** ******@TK2MSFTN GP14.phx.gbl...

can someone tell me what exactly a "property" is in a C# class? As far as
I can see it is "two methods" - ie a getter and a setter for an instance
variable.

Thanks for all the helpful and informative answers.

Peter