C# properties... no parameters

[MC D]

Hi,

I'm trying to write a class that inherits from
System.Collections.CollectionBase, and I want to expose the Item property
for both Get and Set. However because C# doesn't support property
parameters, I can NOT do the following:

public TabData Item(int index)
{
get
{
return (TabData)List[index];
}
set
{
(TabData)List[index] = value;
}
}

In my code I want to be able to write "myCollection[i] = x" , as well as "x
= myCollection[i]", so how can this be done?

I know that you could create a function that sets it, OR returns it, but the
above methodology is so common there must be a way...

-D
(a former VB guy)

[Rob Windsor]

D,

You need to use an indexer. This is KIND OF the same as a default property
in Classic VB. Here's an example

public TabData this[int index]
{
get {return (TabData)this.List[index];}
set {(TabData)this.List[index] = value;}
}

For more information check out
http://www.csharphelp.com/archives/archive140.html

--
Rob Windsor
G6 Consulting
Toronto, Canada

"MC D" <no****@earthtalk.com> wrote in message
news:vl************@corp.supernews.com...

Hi,

I'm trying to write a class that inherits from
System.Collections.CollectionBase, and I want to expose the Item property
for both Get and Set. However because C# doesn't support property
parameters, I can NOT do the following:

public TabData Item(int index)
{
get
{
return (TabData)List[index];
}
set
{
(TabData)List[index] = value;
}
}

In my code I want to be able to write "myCollection[i] = x" , as well as "x = myCollection[i]", so how can this be done?

I know that you could create a function that sets it, OR returns it, but the above methodology is so common there must be a way...

-D
(a former VB guy)

[Kevin Westhead]

"Rob Windsor" <rw******@NO.MORE.SPAM.bigfoot.com> wrote in message
news:eU**************@TK2MSFTNGP10.phx.gbl...

You need to use an indexer. This is KIND OF the same as a default property
in Classic VB. Here's an example

public TabData this[int index]
{
get {return (TabData)this.List[index];}
set {(TabData)this.List[index] = value;}
}

For more information check out
http://www.csharphelp.com/archives/archive140.html

In addition to Rob's comments, it's worth pointing out that you cannot have
properties with multiple parameters in C#, although you can in VB. If you
need to consume such a property from C# then you must use the get_ and set_
methods directly.

--
Kevin Westhead

[MC D]

Thanks a bunch for the help! FYI, it is:

set{this.List[index] = (TabData)value;}

not:

set {(TabData)this.List[index] = value;}

unless I'm mistaken about that too! ;o)

"Rob Windsor" <rw******@NO.MORE.SPAM.bigfoot.com> wrote in message
news:eU**************@TK2MSFTNGP10.phx.gbl...

D,

You need to use an indexer. This is KIND OF the same as a default property
in Classic VB. Here's an example

public TabData this[int index]
{
get {return (TabData)this.List[index];}
set {(TabData)this.List[index] = value;}
}

For more information check out
http://www.csharphelp.com/archives/archive140.html

--
Rob Windsor
G6 Consulting
Toronto, Canada

"MC D" <no****@earthtalk.com> wrote in message
news:vl************@corp.supernews.com...

Hi,

I'm trying to write a class that inherits from
System.Collections.CollectionBase, and I want to expose the Item property for both Get and Set. However because C# doesn't support property
parameters, I can NOT do the following:

public TabData Item(int index)
{
get
{
return (TabData)List[index];
}
set
{
(TabData)List[index] = value;
}
}

In my code I want to be able to write "myCollection[i] = x" , as well as

"x

= myCollection[i]", so how can this be done?

I know that you could create a function that sets it, OR returns it, but

the

above methodology is so common there must be a way...

-D
(a former VB guy)

[Lloyd Dupont]

I don't understand what you said but that inspire me the following comment
nonetheless.

1st property have no parameter.
2nd: indexer could have as many paramenter as you wish, even a variable
number

"Kevin Westhead" <ke****@NOSPAM.i2DOTcoDOTuk> wrote in message
news:u6**************@TK2MSFTNGP10.phx.gbl...

"Rob Windsor" <rw******@NO.MORE.SPAM.bigfoot.com> wrote in message
news:eU**************@TK2MSFTNGP10.phx.gbl...

You need to use an indexer. This is KIND OF the same as a default property in Classic VB. Here's an example

public TabData this[int index]
{
get {return (TabData)this.List[index];}
set {(TabData)this.List[index] = value;}
}

For more information check out
http://www.csharphelp.com/archives/archive140.html

In addition to Rob's comments, it's worth pointing out that you cannot

have properties with multiple parameters in C#, although you can in VB. If you
need to consume such a property from C# then you must use the get_ and set_ methods directly.

--
Kevin Westhead

[Jon Skeet]

Kevin Westhead <ke****@NOSPAM.i2DOTcoDOTuk> wrote:

In addition to Rob's comments, it's worth pointing out that you cannot have
properties with multiple parameters in C#, although you can in VB. If you
need to consume such a property from C# then you must use the get_ and set_
methods directly.

Just to expand on Lloyd's comments, here is a program demonstrating an
indexer with multiple parameters:

using System;

public class Test
{
static void Main()
{
Test t = new Test();
Console.WriteLine (t[5, 6]);
}

int this[int x, int y]
{
get { return x*y; }
}
}

What you *can't* do in C# is have multiple indexers with the *same*
parameter list, which you can in VB.NET by giving them different names.

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet/
If replying to the group, please do not mail me too

[Kevin Westhead]

"Jon Skeet" <sk***@pobox.com> wrote in message
news:MP************************@news.microsoft.com ...

Just to expand on Lloyd's comments, here is a program demonstrating an
indexer with multiple parameters:

using System;

public class Test
{
static void Main()
{
Test t = new Test();
Console.WriteLine (t[5, 6]);
}

int this[int x, int y]
{
get { return x*y; }
}
}

What you *can't* do in C# is have multiple indexers with the *same*
parameter list, which you can in VB.NET by giving them different names.

Yes, I should have stressed that I was just talking about plain properties
rather than indexers, which was slightly OT. In otherwords I can write the
following property in VB but not in C# (although I can consume it from C#):

Public ReadOnly Property ItemIterator(mask As ItemMask, startIndex As
Integer) As MaskedItemIterator
Get
Return m_itemIterator.GetIteratorFromMask(mask, startIndex)
End Get
End Property

I'm assuming VB.NET has this feature for compatibility with VB6, whereas in
C# they are enforcing a stricter relationship between properties and class
members, hence you have to call the above property as if it was a method.

--
Kevin Westhead

[Jon Skeet]

Kevin Westhead <ke****@NOSPAM.i2DOTcoDOTuk> wrote:

Yes, I should have stressed that I was just talking about plain properties
rather than indexers, which was slightly OT.
In that case the word "multiple" is entirely superfluous - you can't
have properties which take parameters *at all* in C#, because a
property with a parameter basically *is* called an indexer.
In otherwords I can write the
following property in VB but not in C# (although I can consume it from C#):
<snip>

Well, you can write it in C# - you'd just call it an indexer instead. The IL
generated could be pretty much exactly the same, I believe.
I'm assuming VB.NET has this feature for compatibility with VB6, whereas in
C# they are enforcing a stricter relationship between properties and class
members, hence you have to call the above property as if it was a method.

Nope - you could make it an indexer with no problems. As I said before,
the only problem is that although you can name indexers, you can't
*use* them by name.

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet/
If replying to the group, please do not mail me too

[Rob Windsor]

That's what you get when you try to write code in your news reader :-)
Actually you don't need to cast the object in the set so the could would
normally be

set {this.List[index] = value;}

Rob

"MC D" <no****@earthtalk.com> wrote in message
news:vl************@corp.supernews.com...

Thanks a bunch for the help! FYI, it is:

set{this.List[index] = (TabData)value;}

not:

set {(TabData)this.List[index] = value;}

unless I'm mistaken about that too! ;o)

"Rob Windsor" <rw******@NO.MORE.SPAM.bigfoot.com> wrote in message
news:eU**************@TK2MSFTNGP10.phx.gbl...

D,

You need to use an indexer. This is KIND OF the same as a default property

in Classic VB. Here's an example

public TabData this[int index]
{
get {return (TabData)this.List[index];}
set {(TabData)this.List[index] = value;}
}

For more information check out
http://www.csharphelp.com/archives/archive140.html

--
Rob Windsor
G6 Consulting
Toronto, Canada

"MC D" <no****@earthtalk.com> wrote in message
news:vl************@corp.supernews.com...

Hi,

I'm trying to write a class that inherits from
System.Collections.CollectionBase, and I want to expose the Item property for both Get and Set. However because C# doesn't support property
parameters, I can NOT do the following:

public TabData Item(int index)
{
get
{
return (TabData)List[index];
}
set
{
(TabData)List[index] = value;
}
}

In my code I want to be able to write "myCollection[i] = x" , as well

as "x

= myCollection[i]", so how can this be done?

I know that you could create a function that sets it, OR returns it,

but the

above methodology is so common there must be a way...

-D
(a former VB guy)