Comparing elegantly when there may be a type mismatch

[Michael A. Covington]

I'm handing the sort event of a DataGridView, because if I don't handle it,
there's an exception whenever I try to sort a column whose elements are not
all the same type.

I'd like to write a routine which:

- Tries to sort each pair of elements using the comparer that is appropriate
to their type;
- If they are not the same type or there is no comparer, then does a
ToString() and compares the strings.

I have a kluge working (which tries several common types one by one), but
what is the most elegant way to do this?

[Michael A. Covington]

"Michael A. Covington" <lo**@ai.uga.edu.for.address> wrote in message
news:%2******************@TK2MSFTNGP03.phx.gbl...

I'd like to write a routine which:

- Tries to sort each pair of elements using the comparer that is
appropriate to their type;
- If they are not the same type or there is no comparer, then does a
ToString() and compares the strings.

I have a kluge working (which tries several common types one by one), but
what is the most elegant way to do this?

Actually, here is something I came up with that seems to fill the bill.
e.CellValue1 and e.CellValue2 are objects to be compared; they are of
unknown type but are usually common things (int, double, or string) and are
usually of the same type. Comments would be appreciated.

Type t = e.CellValue1.GetType();
if (e.CellValue2.GetType() == t && t is IComparable)
{
e.SortResult = (e.CellValue1 as IComparable).CompareTo(e.CellValue2);
}
// Otherwise compare their string representations
else
{
e.SortResult = System.String.Compare(
e.CellValue1.ToString(), e.CellValue2.ToString());
}

[John B]

Michael A. Covington wrote:

"Michael A. Covington" <lo**@ai.uga.edu.for.address> wrote in message
news:%2******************@TK2MSFTNGP03.phx.gbl...

I'd like to write a routine which:

- Tries to sort each pair of elements using the comparer that is
appropriate to their type;
- If they are not the same type or there is no comparer, then does a
ToString() and compares the strings.

I have a kluge working (which tries several common types one by one), but
what is the most elegant way to do this?
Actually, here is something I came up with that seems to fill the bill.
e.CellValue1 and e.CellValue2 are objects to be compared; they are of
unknown type but are usually common things (int, double, or string) and are
usually of the same type. Comments would be appreciated.

Type t = e.CellValue1.GetType();
if (e.CellValue2.GetType() == t && t is IComparable)
{
e.SortResult = (e.CellValue1 as IComparable).CompareTo(e.CellValue2);
}
// Otherwise compare their string representations
else
{
e.SortResult = System.String.Compare(
e.CellValue1.ToString(), e.CellValue2.ToString());
}

'Twas the way I originally thought but what behaviour do you want in the
case of float and int?
maybe:

.... else
{ double a, b;
if(double.TryParse(e.CellValue1.ToString(), out a) &&
double.TryParse(e.CellValue2.ToString(), out b))
{
e.SortResult = a.CompareTo(b);
}
else
{ e.SortResult = System.String.Compare(
e.CellValue1.ToString(), e.CellValue2.ToString());
}

}

Always depends if you want this behaviour and it might introduce another
level of complexity in terms of culture specific parsing etc...

[Michael A. Covington]

Good suggestion. Mixed floating-point and integer values might be fairly
common, in fact. Thanks!

"John B" <jb******@yahoo.com> wrote in message
news:44**********@news.iprimus.com.au...

Michael A. Covington wrote:

"Michael A. Covington" <lo**@ai.uga.edu.for.address> wrote in message
news:%2******************@TK2MSFTNGP03.phx.gbl...

I'd like to write a routine which:

- Tries to sort each pair of elements using the comparer that is
appropriate to their type;
- If they are not the same type or there is no comparer, then does a
ToString() and compares the strings.

I have a kluge working (which tries several common types one by one),
but what is the most elegant way to do this?

Actually, here is something I came up with that seems to fill the bill.
e.CellValue1 and e.CellValue2 are objects to be compared; they are of
unknown type but are usually common things (int, double, or string) and
are usually of the same type. Comments would be appreciated.

Type t = e.CellValue1.GetType();
if (e.CellValue2.GetType() == t && t is IComparable)
{
e.SortResult = (e.CellValue1 as
IComparable).CompareTo(e.CellValue2);
}
// Otherwise compare their string representations
else
{
e.SortResult = System.String.Compare(
e.CellValue1.ToString(), e.CellValue2.ToString());
}

'Twas the way I originally thought but what behaviour do you want in the
case of float and int?
maybe:

...

else
{

double a, b;
if(double.TryParse(e.CellValue1.ToString(), out a) &&
double.TryParse(e.CellValue2.ToString(), out b))
{
e.SortResult = a.CompareTo(b);
}
else
{

e.SortResult = System.String.Compare(
e.CellValue1.ToString(), e.CellValue2.ToString());
}

}

Always depends if you want this behaviour and it might introduce another
level of complexity in terms of culture specific parsing etc...