IDataErrorInfo Interface

[Brian]

I really want to use the IDataErrorInfo interface. I'm using it now in
combination with an ErrorProvider and this seems really good.

But the downside: IDataErrorInfo wants to use a string indexer on my
class. No big deal, but now I have a class where I want to use my own
string indexer. This is frustrating.

Do I have to do something funky like add an extra argument to my
indexer? Is there a better way?

Help...

--Brian

 
 
class MyClass
{
//Here is the indexer for IDataErrorInfo:
public string this[string name]
{
get { ... }
}
 
//Here is my indexer:
public string this[string name, bool x]
{
get { ... }
}
}
 
 

[Barry Kelly]

Brian <[e-mail]> wrote:

I really want to use the IDataErrorInfo interface. I'm using it now in
combination with an ErrorProvider and this seems really good.

But the downside: IDataErrorInfo wants to use a string indexer on my
class. No big deal, but now I have a class where I want to use my own
string indexer. This is frustrating.

Do I have to do something funky like add an extra argument to my
indexer? Is there a better way?
Yes. Use explicit interface implementation.
class MyClass class MyClass : IDataErrorInfo {
//Here is the indexer for IDataErrorInfo:
public string this[string name] string IDataErrorInfo.this[string name] {
get { ... }
}

//Here is my indexer:
public string this[string name, bool x] public string this[string name] {
get { ... }
}
}

-- Barry

--
http://barrkel.blogspot.com/

[Tom Spink]

Brian wrote:

I really want to use the IDataErrorInfo interface. I'm using it now in
combination with an ErrorProvider and this seems really good.

But the downside: IDataErrorInfo wants to use a string indexer on my
class. No big deal, but now I have a class where I want to use my own
string indexer. This is frustrating.

Do I have to do something funky like add an extra argument to my
indexer? Is there a better way?

Help...

--Brian

      class MyClass
      {
          //Here is the indexer for IDataErrorInfo:
          public string this[string name]
          {
              get { ... }
          }

          //Here is my indexer:
          public string this[string name, bool x]
          {
              get { ... }
          }
      }

 

Hi Brian, just explicitly implement the IDataErrorInfo interface:

class MyClass
{
public IDataErrorInfo.this[string columnName]
{
get { ... }
}

public string this[string name]
{
get { ... }
}
}

This does however introduce some implications when you want to access the
IDataErrorInfo implementation of the indexer, that is, the instance of
MyClass will need to be explicitly cast to IDataErrorInfo in order to
access the implementation of the indexer:

((IDataErrorInfo)MyClassInstance)["foobar"]

Hope this helps,
-- Tom Spink

[Frans Bouma [C# MVP]]

Brian wrote:

I really want to use the IDataErrorInfo interface. I'm using it now
in combination with an ErrorProvider and this seems really good.

But the downside: IDataErrorInfo wants to use a string indexer on my
class. No big deal, but now I have a class where I want to use my
own string indexer. This is frustrating.

Do I have to do something funky like add an extra argument to my
indexer? Is there a better way?

The IDataErrorInfo interface is used for runtime databinding info
reporting, it's not used for error info reporting for your own usage.
This means that the bound controls know what to pass to IDataErrorInfo
to retrieve an error message. If you want to use the IDataErrorInfo
interface for something else, you're using it for a different purpose
and then it might well be that it pretty lacks a lot. So for those
purposes, implement your own interface.

FB

--
------------------------------------------------------------------------
Lead developer of LLBLGen Pro, the productive O/R mapper for .NET
LLBLGen Pro website: http://www.llblgen.com
My .NET blog: http://weblogs.asp.net/fbouma
Microsoft MVP (C#)
------------------------------------------------------------------------

[Brian]

Tom Spink wrote:

Brian wrote:

I really want to use the IDataErrorInfo interface. I'm using it now in
combination with an ErrorProvider and this seems really good.

But the downside: IDataErrorInfo wants to use a string indexer on my
class. No big deal, but now I have a class where I want to use my own
string indexer. This is frustrating.

Do I have to do something funky like add an extra argument to my
indexer? Is there a better way?

Help...

--Brian

      class MyClass
      {
          //Here is the indexer for IDataErrorInfo:
          public string this[string name]
          {
              get { ... }
          }

          //Here is my indexer:
          public string this[string name, bool x]
          {
              get { ... }
          }
      }

 

Hi Brian, just explicitly implement the IDataErrorInfo interface:

class MyClass
{
public IDataErrorInfo.this[string columnName]
{
get { ... }
}

public string this[string name]
{
get { ... }
}
}

This does however introduce some implications when you want to access the
IDataErrorInfo implementation of the indexer, that is, the instance of
MyClass will need to be explicitly cast to IDataErrorInfo in order to
access the implementation of the indexer:

((IDataErrorInfo)MyClassInstance)["foobar"]

Hope this helps,
-- Tom Spink

That is AWESOME!!!

Oh this is too cool. Thank you guys so much!

--Brian