InvalidCastException in DataGridView
- by Max Yaffe
(Using VS 2010 Beta 2 - .Net 4.0 B2 Rel)
I have a class, MyTable, derived from BindingList where S is a struct. S is made up of several other structs, for example:
public class MyTable<S>:BindingList<S> where S: struct
{
...
}
public struct MyStruct
{
public MyReal r1;
public MyReal r2;
public MyReal R1 {get{...} set{...}}
public MyReal R2 {get{...} set{...}}
...
}
public struct MyReal
{
private Double d;
private void InitFromString(string) {this.d = ...;}
public MyReal(Double d) { this.d = d;}
public MyReal(string val) { this.d = default(Double); InitFromString(val);}
public override string ToString() { return this.real.ToString();}
public static explicit operator MyReal(string s) { return new MyReal(s);}
public static implicit operator String(MyReal r) { return r.ToString();}
...
}
OK, I use the MyTable as a binding source for a DataGridView. I can load the data grid easily using InitFromString on individual fields in MyStruct.
The problem comes when I try to edit a value in a cell of the DataGridView. Going to the first row, first column, I change the value of the existing number. It gives an exception blizzard, the first line of which says:
System.FormatException: Invalid cast from 'System.String' to 'MyReal'
I've looked at the casting discussions and reference books but don't see any obvious problems.
Any ideas?
