Default properties

[Chuck Bowling]

Maybe I'm doing something wrong or just don't understand the concept, but
i'm having a problem with default properties.

My impression of how a default property should act is this;

MyClass c = new MyClass();

c = "my text";

In the line above, the string is assigned to a field in the class instance.

If I'm understanding correctly, the way to declare a default property in C#
is to use an indexer like so:

public string this[int i]
{
get{return myString; }
set { myString = value; }
}

I tried this and the only way I could make it work was like so;

c[0] = "my new text";

How is this a default property? It looks to me like no more than a crippled
indexer.

[Fakher Halim]

Chuck,
Please refer to
http://msdn.microsoft.com/library/de...components.asp

MyClass c = new MyClass();
c = "my text"; Actually it is wrong to try to expect assigning strings to object c, as c
has a type MyClass.

Even assigning of a string to c[0] is not exactly very intuitive c[0] = "my new text";
The reason why you would want to use indexer is to select ONE ITEM out of a
collection.
Like one Widget out of Widgets class, as it is done in MSDN example I
recommended.
The only benefit is: Instead of having to specify (say)
Widgets.Item[3].Status, you can use Widgets[3].Status.

The VB6 style parameterless default prperty is not really encouraged in
..NET.

Fakher Halim
Software Architect
TPG

"Chuck Bowling" <ch**********@s bcglobal-NO-SPAM.net> wrote in message
news:O9******** ******@TK2MSFTN GP10.phx.gbl... Maybe I'm doing something wrong or just don't understand the concept, but
i'm having a problem with default properties.

My impression of how a default property should act is this;
In the line above, the string is assigned to a field in the class instance.
If I'm understanding correctly, the way to declare a default property in C# is to use an indexer like so:

public string this[int i]
{
get{return myString; }
set { myString = value; }
}

I tried this and the only way I could make it work was like so;

c[0] = "my new text";

How is this a default property? It looks to me like no more than a crippled indexer.

[Fakher Halim]

A more specific example at:
http://msdn.microsoft.com/library/en...asp?frame=true

"Fakher Halim" <fa****@msn.com > wrote in message
news:%2******** *******@TK2MSFT NGP12.phx.gbl.. .

Chuck,
Please refer to
http://msdn.microsoft.com/library/de...components.asp

MyClass c = new MyClass();
c = "my text";

Actually it is wrong to try to expect assigning strings to object c, as c
has a type MyClass.

Even assigning of a string to c[0] is not exactly very intuitive

c[0] = "my new text";

The reason why you would want to use indexer is to select ONE ITEM out of

a collection.
Like one Widget out of Widgets class, as it is done in MSDN example I
recommended.
The only benefit is: Instead of having to specify (say)
Widgets.Item[3].Status, you can use Widgets[3].Status.

The VB6 style parameterless default prperty is not really encouraged in
.NET.

Fakher Halim
Software Architect
TPG

"Chuck Bowling" <ch**********@s bcglobal-NO-SPAM.net> wrote in message
news:O9******** ******@TK2MSFTN GP10.phx.gbl...

Maybe I'm doing something wrong or just don't understand the concept, but i'm having a problem with default properties.

My impression of how a default property should act is this;
In the line above, the string is assigned to a field in the class

instance.

If I'm understanding correctly, the way to declare a default property in

C#

is to use an indexer like so:

public string this[int i]
{
get{return myString; }
set { myString = value; }
}

I tried this and the only way I could make it work was like so;

c[0] = "my new text";

How is this a default property? It looks to me like no more than a

crippled

indexer.

[Chuck Bowling]

Thank you for the response. I understand how to use indexers and their
purpose and i think they are a great idea. However, my gripe is specifically
what you mentioned below. My idea of a default property is the style of VB6.
The current C# syntax is simply an indexer. MS help describes this as a
method for setting default properties. A lack of distinction that can be
confusing for the layman...
"Fakher Halim" <fa****@msn.com > wrote in message
news:%2******** *******@TK2MSFT NGP12.phx.gbl.. .

Chuck,
Please refer to
http://msdn.microsoft.com/library/de...components.asp

MyClass c = new MyClass();
c = "my text";

Actually it is wrong to try to expect assigning strings to object c, as c
has a type MyClass.

Even assigning of a string to c[0] is not exactly very intuitive

c[0] = "my new text";

The reason why you would want to use indexer is to select ONE ITEM out of

a collection.
Like one Widget out of Widgets class, as it is done in MSDN example I
recommended.
The only benefit is: Instead of having to specify (say)
Widgets.Item[3].Status, you can use Widgets[3].Status.

The VB6 style parameterless default prperty is not really encouraged in
.NET.

Fakher Halim
Software Architect
TPG

"Chuck Bowling" <ch**********@s bcglobal-NO-SPAM.net> wrote in message
news:O9******** ******@TK2MSFTN GP10.phx.gbl...

Maybe I'm doing something wrong or just don't understand the concept, but i'm having a problem with default properties.

My impression of how a default property should act is this;
In the line above, the string is assigned to a field in the class

instance.

If I'm understanding correctly, the way to declare a default property in

C#

is to use an indexer like so:

public string this[int i]
{
get{return myString; }
set { myString = value; }
}

I tried this and the only way I could make it work was like so;

c[0] = "my new text";

How is this a default property? It looks to me like no more than a

crippled

indexer.

[Fakher Halim]

You are right, Chuck. It is not at all default property.
For instance, In VB6, you could just skip the Caption Property of a label
control (a class instance in C#), and just assign a string to it
Both of the following were allowed:
lblEnterName.Ca ption = "Enter full name"
lblEnterName = "Enter full name"

Since .NET languages are stongly typed, only comptible data types could be
assigned to a class instance (what used to be a VB6 control).
Doing same in .NET would complain "Cannot implicity convert string to
System.Windows. Forms.Label."
Frankely I can't imagine why it shoud not.
Fakher Halim

"Chuck Bowling" <ch**********@s bcglobal-NO-SPAM.net> wrote in message
news:%2******** ********@TK2MSF TNGP09.phx.gbl. ..

Thank you for the response. I understand how to use indexers and their
purpose and i think they are a great idea. However, my gripe is specifically what you mentioned below. My idea of a default property is the style of VB6. The current C# syntax is simply an indexer. MS help describes this as a
method for setting default properties. A lack of distinction that can be
confusing for the layman...
"Fakher Halim" <fa****@msn.com > wrote in message
news:%2******** *******@TK2MSFT NGP12.phx.gbl.. .

Chuck,
Please refer to

http://msdn.microsoft.com/library/de...components.asp

MyClass c = new MyClass();
c = "my text";

Actually it is wrong to try to expect assigning strings to object c, as c

has a type MyClass.

Even assigning of a string to c[0] is not exactly very intuitive

c[0] = "my new text";

The reason why you would want to use indexer is to select ONE ITEM out of a

collection.
Like one Widget out of Widgets class, as it is done in MSDN example I
recommended.
The only benefit is: Instead of having to specify (say)
Widgets.Item[3].Status, you can use Widgets[3].Status.

The VB6 style parameterless default prperty is not really encouraged in
.NET.

Fakher Halim
Software Architect
TPG

"Chuck Bowling" <ch**********@s bcglobal-NO-SPAM.net> wrote in message
news:O9******** ******@TK2MSFTN GP10.phx.gbl...

Maybe I'm doing something wrong or just don't understand the concept,

but i'm having a problem with default properties.

My impression of how a default property should act is this;
In the line above, the string is assigned to a field in the class

instance.

If I'm understanding correctly, the way to declare a default property

in C#

is to use an indexer like so:

public string this[int i]
{
get{return myString; }
set { myString = value; }
}

I tried this and the only way I could make it work was like so;

c[0] = "my new text";

How is this a default property? It looks to me like no more than a

crippled

indexer.

[Fakher Halim]

Chuck,
I have been trying to figure out the best way of simulating VB6 style default property in C#
as:
MyClass c="Fakher Halim";//asing a constant string directly to any class instance
Console.WriteLi ne(c); //print it to verify

It is implemented in the following class using implicit type casting operator
class MyClass{//Has Text Property, as default
//Ability to assign strings directly to .Text Property of MyClass -- Like VB6
public static implicit operator MyClass(string s) {
MyClass c=new MyClass();
c.Text=s;
return c;
}
private string _Text;
public string Text{
get{return _Text; }
set { _Text = value; }
}
public override string ToString() { return Text;}
}

Fakher Halim
Software Architect
TPG

"Fakher Halim" <fa****@msn.com > wrote in message news:%2******** **********@TK2M SFTNGP09.phx.gb l...

You are right, Chuck. It is not at all default property.
For instance, In VB6, you could just skip the Caption Property of a label
control (a class instance in C#), and just assign a string to it
Both of the following were allowed:
lblEnterName.Ca ption = "Enter full name"
lblEnterName = "Enter full name"

Since .NET languages are stongly typed, only comptible data types could be
assigned to a class instance (what used to be a VB6 control).
Doing same in .NET would complain "Cannot implicity convert string to
System.Windows. Forms.Label."
Frankely I can't imagine why it shoud not.
Fakher Halim

"Chuck Bowling" <ch**********@s bcglobal-NO-SPAM.net> wrote in message
news:%2******** ********@TK2MSF TNGP09.phx.gbl. ..

Thank you for the response. I understand how to use indexers and their
purpose and i think they are a great idea. However, my gripe is

specifically

what you mentioned below. My idea of a default property is the style of

VB6.

The current C# syntax is simply an indexer. MS help describes this as a
method for setting default properties. A lack of distinction that can be
confusing for the layman...
"Fakher Halim" <fa****@msn.com > wrote in message
news:%2******** *******@TK2MSFT NGP12.phx.gbl.. .

Chuck,
Please refer to

http://msdn.microsoft.com/library/de...components.asp

> MyClass c = new MyClass();
> c = "my text";
Actually it is wrong to try to expect assigning strings to object c, as c has a type MyClass.

Even assigning of a string to c[0] is not exactly very intuitive
> c[0] = "my new text";

The reason why you would want to use indexer is to select ONE ITEM out of

a

collection.
Like one Widget out of Widgets class, as it is done in MSDN example I
recommended.
The only benefit is: Instead of having to specify (say)
Widgets.Item[3].Status, you can use Widgets[3].Status.

The VB6 style parameterless default prperty is not really encouraged in
.NET.

Fakher Halim
Software Architect
TPG

"Chuck Bowling" <ch**********@s bcglobal-NO-SPAM.net> wrote in message
news:O9******** ******@TK2MSFTN GP10.phx.gbl...
> Maybe I'm doing something wrong or just don't understand the concept,

but

> i'm having a problem with default properties.
>
> My impression of how a default property should act is this;
>
>
> In the line above, the string is assigned to a field in the class
instance.
>
> If I'm understanding correctly, the way to declare a default property

in C#
> is to use an indexer like so:
>
> public string this[int i]
> {
> get{return myString; }
> set { myString = value; }
> }
>
> I tried this and the only way I could make it work was like so;
>
> c[0] = "my new text";
>
> How is this a default property? It looks to me like no more than a
crippled
> indexer.
>
>