Generics and comparison (follow on from my previous "Generics and collections" thread)

[Martin Robins]

Marc has sorted my problem with the collections, however I am now in a new scenario; I am trying to compare a generic property value before setting it as shown below ...

public T Value {
get { return this.value; }
set {
if ( this.value != value ) {
this.value = value;
this.OnValueCha nged(EventArgs. Empty);
}
}
}

This code produces the Operator '==' cannot be applied to operands of type 'T' and 'T' error at compile time!
I am sure that I am not the only person to have tried this, any clues as to the correct work around?

I have tried restricting 'T' to IComparable in a where clause and then casting 'this.value' and 'value' to IComparable for the comparison - the code then compiles but is this the right answer? It feels wrong, but I am quickly learning that my own understanding of generics is much lower than I thought it was!

Thanks in advance.

[Martin Robins]

Re: Generics and comparison (follow on from my previous "Generi cs and collections&quo t; thread)

Though it compiles, the original IComparable idea did not work; the comparisons would often return incorrect results.

I have resolved it for now using "if ( this.value == null ? value != null : !this.value.Equ als(value) )" but I am still open to a better way if it exists ...

Martin.

"Martin Robins" <martin at orpheus-solutions dot co dot ukwrote in message news:ujRpfRnlIH A.536@TK2MSFTNG P06.phx.gbl...
Marc has sorted my problem with the collections, however I am now in a new scenario; I am trying to compare a generic property value before setting it as shown below ...

public T Value {
get { return this.value; }
set {
if ( this.value != value ) {
this.value = value;
this.OnValueCha nged(EventArgs. Empty);
}
}
}

This code produces the Operator '==' cannot be applied to operands of type 'T' and 'T' error at compile time!
I am sure that I am not the only person to have tried this, any clues as to the correct work around?

I have tried restricting 'T' to IComparable in a where clause and then casting 'this.value' and 'value' to IComparable for the comparison - the code then compiles but is this the right answer? It feels wrong, but I am quickly learning that my own understanding of generics is much lower than I thought it was!

Thanks in advance.

[Rudy Velthuis]

Re: Generics and comparison (follow on from my previous &quot;Generi cs and collections&quo t; thread)

Martin Robins wrote:

Though it compiles, the original IComparable idea did not work; the
comparisons would often return incorrect results.

That is a problem with the implementation of the interface for that
particular instantiation of T, then. If it were correctly implemented,
that should not happen.
--
Rudy Velthuis http://rvelthuis.de

"Sailors ought never to go to church. They ought to go to hell,
where it is much more comfortable." -- HG Wells.