Typecasting without knowing the cast

Hi

I have a data row variable which could be for any of a number of tables in
my apps. How can I type cast the variable to correct type at runtime? I know
I can get the type description using MyRow.ToString but don't know how to
use this to typecast MyRow variable. I need this to write a generic SUB that
can deal with rows of any table type.

Thanks

Regards

Armin
Mon Apr 28 15:24:31 CDT 2008

"John" <info@nospam.infovis.co.uk> schrieb
> Hi
>
> I have a data row variable which could be for any of a number of
> tables in my apps. How can I type cast the variable to correct type
> at runtime? I know I can get the type description using
> MyRow.ToString but don't know how to use this to typecast MyRow
> variable. I need this to write a generic SUB that can deal with rows
> of any table type.

Maybe you are looking for this:

if typeof row is CustomerRow then
directcast(row, CustomerRow).Member 'any type specific member
elseif typeof row is contractRow then

'...

end if

Type casting without knowing the destination type at design time does
not make sense. Casting is there to be able to write code that is
specific to a certain type. If you don't know the destination type, you
can not write type specific code.


Armin

kimiraikkonen
Mon Apr 28 16:24:13 CDT 2008

On Apr 28, 10:31 pm, "John" <i...@nospam.infovis.co.uk> wrote:
> Hi
>
> I have a data row variable which could be for any of a number of tables in
> my apps. How can I type cast the variable to correct type at runtime? I know
> I can get the type description using MyRow.ToString but don't know how to
> use this to typecast MyRow variable. I need this to write a generic SUB that
> can deal with rows of any table type.
>
> Thanks
>
> Regards

John,
To know the type of object, use GetType function to determine. Then
maybe you'll have a change for type casting.

Hope this helps,

Onur

Tom
Mon Apr 28 17:22:37 CDT 2008

On 2008-04-28, John <info@nospam.infovis.co.uk> wrote:
> Hi
>
> I have a data row variable which could be for any of a number of tables in
> my apps. How can I type cast the variable to correct type at runtime? I know
> I can get the type description using MyRow.ToString but don't know how to
> use this to typecast MyRow variable. I need this to write a generic SUB that
> can deal with rows of any table type.
>
> Thanks
>
> Regards
>
>

Assuming that Row inherits from DataRow, then that is the type you would
be working with.

--
Tom Shelton

John
Mon Apr 28 17:37:53 CDT 2008

I am trying

CType(MyRow, GetType(MyRow))

but it says 'Error 1 Keyword does not name a type' on GetType.

Thanks

Regards


"kimiraikkonen" <kimiraikkonen85@gmail.com> wrote in message
news:0be0e139-0b2a-4e4b-bf00-ec6050923a70@a70g2000hsh.googlegroups.com...
> On Apr 28, 10:31 pm, "John" <i...@nospam.infovis.co.uk> wrote:
>> Hi
>>
>> I have a data row variable which could be for any of a number of tables
>> in
>> my apps. How can I type cast the variable to correct type at runtime? I
>> know
>> I can get the type description using MyRow.ToString but don't know how to
>> use this to typecast MyRow variable. I need this to write a generic SUB
>> that
>> can deal with rows of any table type.
>>
>> Thanks
>>
>> Regards
>
> John,
> To know the type of object, use GetType function to determine. Then
> maybe you'll have a change for type casting.
>
> Hope this helps,
>
> Onur

Armin
Mon Apr 28 17:44:22 CDT 2008

"John" <info@nospam.infovis.co.uk> schrieb
> I am trying
>
> CType(MyRow, GetType(MyRow))
>
> but it says 'Error 1 Keyword does not name a type' on GetType.

Have you read my message? Why do you want to cast at all?


Armin

John
Mon Apr 28 17:58:04 CDT 2008

I am writing a library of generalised SUB to handle any table's row that the
user using the library may need to pass to library. I do not know the actual
type of the data row that user will be passing therefore I need to figure it
at runtime.

Thanks

Regards

"Armin Zingler" <az.nospam@freenet.de> wrote in message
news:Oh95aKYqIHA.3940@TK2MSFTNGP03.phx.gbl...
> "John" <info@nospam.infovis.co.uk> schrieb
>> I am trying
>>
>> CType(MyRow, GetType(MyRow))
>>
>> but it says 'Error 1 Keyword does not name a type' on GetType.
>
> Have you read my message? Why do you want to cast at all?
>
>
> Armin

Armin
Mon Apr 28 18:14:50 CDT 2008

"John" <info@nospam.infovis.co.uk> schrieb
> I am writing a library of generalised SUB to handle any table's row
> that the user using the library may need to pass to library. I do
> not know the actual type of the data row that user will be passing
> therefore I need to figure it at runtime.

Sry, I don't get it. If you don't know the actual type, how do you want
to handle different types differently? That's a contradiction.

If you determine the type at _runtime_, how do you want to take the type
into account at _design time_? Design time is before runtime.


Armin

Tom
Mon Apr 28 18:38:54 CDT 2008

On 2008-04-28, John <info@nospam.infovis.co.uk> wrote:
> I am writing a library of generalised SUB to handle any table's row that the
> user using the library may need to pass to library. I do not know the actual
> type of the data row that user will be passing therefore I need to figure it
> at runtime.
>
> Thanks

John,

What kind of actions are you trying to take on these rows? Basically,
what I'm saying, is unless you know the type or the types that can be
passed, then you can't get there from here....

Like I said, you can handle all the Rows as DataRow, and that is about
as close as your going to get.

--
Tom Shelton

John
Mon Apr 28 18:46:58 CDT 2008

Thanks. I know what you mean.

Regards

"Armin Zingler" <az.nospam@freenet.de> wrote in message
news:ODER3WYqIHA.4292@TK2MSFTNGP04.phx.gbl...
> "John" <info@nospam.infovis.co.uk> schrieb
>> I am writing a library of generalised SUB to handle any table's row
>> that the user using the library may need to pass to library. I do
>> not know the actual type of the data row that user will be passing
>> therefore I need to figure it at runtime.
>
> Sry, I don't get it. If you don't know the actual type, how do you want
> to handle different types differently? That's a contradiction.
>
> If you determine the type at _runtime_, how do you want to take the type
> into account at _design time_? Design time is before runtime.
>
>
> Armin
>

John
Mon Apr 28 18:47:07 CDT 2008

Got it. Thanks

Regards

"Tom Shelton" <tom_shelton@YOUKNOWTHEDRILLcomcast.net> wrote in message
news:%23kDDGkYqIHA.1164@TK2MSFTNGP04.phx.gbl...
> On 2008-04-28, John <info@nospam.infovis.co.uk> wrote:
>> I am writing a library of generalised SUB to handle any table's row that
>> the
>> user using the library may need to pass to library. I do not know the
>> actual
>> type of the data row that user will be passing therefore I need to figure
>> it
>> at runtime.
>>
>> Thanks
>
> John,
>
> What kind of actions are you trying to take on these rows? Basically,
> what I'm saying, is unless you know the type or the types that can be
> passed, then you can't get there from here....
>
> Like I said, you can handle all the Rows as DataRow, and that is about
> as close as your going to get.
>
> --
> Tom Shelton

Cor
Tue Apr 29 00:29:55 CDT 2008

http://msdn2.microsoft.com/en-us/library/system.data.common.dbdataadapter.fillschema(vs.71).aspx

http://msdn2.microsoft.com/en-us/library/system.data.datacolumn.datatype(VS.71).aspx

Cor


"John" <info@nospam.infovis.co.uk> schreef in bericht
news:OFrcnZWqIHA.3680@TK2MSFTNGP05.phx.gbl...
> Hi
>
> I have a data row variable which could be for any of a number of tables in
> my apps. How can I type cast the variable to correct type at runtime? I
> know I can get the type description using MyRow.ToString but don't know
> how to use this to typecast MyRow variable. I need this to write a generic
> SUB that can deal with rows of any table type.
>
> Thanks
>
> Regards
>