Passing arguments to custom databinding expression function

Hi,

 I am using a gridview and in that gridview i am using a textbox. The textbox is bound to custom databinding expression where i am using a function.

 My question is how can i pass values to that function, for example i want to pass the some other column value from the gridview to that function

 

In below gridview i am using two columns, one is BoundField column, and the other one is TemplateField column.

I want to pass any of or both the column values to the MyFunction() where i am doing some database manipulation and return string result.

Any suggestions please....

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