For the WHY - propably to facilitate the AddNew () behavior that most lists define.
I can see a new (string, int) to be useable at times, but frnakly - even the new() contrain t in itself is GREAT. What I would prefer is the ablity to define static methods and conversions for enums. I sincerely miss the ability of an enum to have static methods attached to it. I have some enums that "represent" a numeric value, but not directly. Stuff like values in the enum being 3.2, 3.5, 3.8 - and sometimes I only need the "3"part out of it. A static method would allow me to say Int I = Enumname.ToGenericInt(enumvalue) :-) Just in case someone at MS reads this. Right now I have to put all these little methods into external utility methods. Thomas Tomiczek THONA Software & Consulting Ltd. (Microsoft MVP C#/.NET) > -----Original Message----- > From: Moderated discussion of advanced .NET topics. > [mailto:[EMAIL PROTECTED] On Behalf Of > Daniel O'Connell > Sent: Freitag, 24. Oktober 2003 03:02 > To: [EMAIL PROTECTED] > Subject: Re: [ADVANCED-DOTNET] C# generics constraints syntax > > On further research(read the c# 2.0 spec doc up on msdn), it > doesn't appear that constructor constaints exist beyond a > default constructor(new()) or how to actually use that > constraint(one would assume you don't have to use reflection > in this situation). However I find that to be a glaring > omission that only default constructors can be defined, any > one have any comments as to why? > > > ----- Original Message ----- > From: "Thong (Tum) Nguyen" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Thursday, October 23, 2003 5:51 PM > Subject: Re: [ADVANCED-DOTNET] C# generics constraints syntax > > > > You're probably right. I'm just toying with alternatives > to the "where" > > clause. > > > > One advantage of the where clause is that it actually looks > quite nice > > if you place it on a separate line... > > > > public class TreeDictionary<K, V> : ICollection > > where K : IComparable > > where V : Object > > > > > > BTW, what does the "new()" do? > > > > ^Tum > > > > > -----Original Message----- > > > From: Moderated discussion of advanced .NET topics. > > > [mailto:ADVANCED- [EMAIL PROTECTED] On Behalf Of Daniel > > > O'Connell > > > Sent: Friday, 24 October 2003 11:26 a.m. > > > To: [EMAIL PROTECTED] > > > Subject: Re: [ADVANCED-DOTNET] C# generics constraints syntax > > > > > > I think convoluting the syntax is a much worse choice > than adding a > > > new keyword. Adding ontop of that the chances of error (<T: (Bar, > > > Bax, > new(), > > > S> > > > which is incorrect and is an easy mistake to make). I > don't know how > > > specific constructor constraints can get, but having a > whole list of > them > > > would make it very easy to not realize you didn't close > the matching (. > > > I find it much cleaner to do, assuming inheritance: > > > > > > public class Dictionary<T,S> : IEnumerable where T : Bar, > Bax, new() > > > where S : IComparable, new() > > > > > > compared to something like > > > > > > public class Dictionary<T : (Bar, Bax, new()), S : (IComparable, > > > new())> > : > > > IEnumerable > > > or > > > public class Dictionary<T : Bar & Bax & new(), S : IComparable & > > > new()> > : > > > IEnumerable > > > > > > (of the two, I prefer the latter actually) > > > > > > The C# syntax as it currently stands is simpler in my > mind, probably > > > understandable to an extent for amateurs, its easy determine what > > > constraint is on what member, and there are no paranthetical > > > screwups that could > get > > > in > > > the way. It also makes figuring out what Dictionary > derives from and > what > > > the constraints are, just by looking for the : and where keywords, > instead > > > of having to do a full fledged mind-parse. > > > > > > I am not a huge fan of the where clause, but I don't > think the other > > > syntaxes suggested solve the biggest underlying problem, which > > > basically is that generics make class declarations much larger, > > > especially as the argument list starts to grow. Imagine 7 > or 8 type > > > arguments with constraints, unlikely as it may be, with > ANY existing > > > syntax...doesn't look pretty does it? > > > > > > > > > ----- Original Message ----- > > > From: "Thong (Tum) Nguyen" <[EMAIL PROTECTED]> > > > To: <[EMAIL PROTECTED]> > > > Sent: Thursday, October 23, 2003 4:46 AM > > > Subject: Re: [ADVANCED-DOTNET] C# generics constraints syntax > > > > > > > > > > I think something along the lines of > > > > > > > > <T : (Bar, Bax), S> would be a reasonable alternative > to the "where" > > > clause. > > > > > > > > ^Tum > > > > > > > > > -----Original Message----- > > > > > From: Moderated discussion of advanced .NET topics. > [mailto:ADVANCED- > > > > > [EMAIL PROTECTED] On Behalf Of Dominic Cooney > > > > > Sent: Thursday, 23 October 2003 1:27 p.m. > > > > > To: [EMAIL PROTECTED] > > > > > Subject: Re: [ADVANCED-DOTNET] C# generics constraints syntax > > > > > > > > > > FWIW, the design of the Java language has gone in the other > direction; > > > the > > > > > syntax is: Foo<T extends Bar, U extends Baz>. I am > not sure how > > > multiple > > > > > constraints are specified (T extends Bar & Baz, IIRC). > > > > > > > > > > What is VB.NET doing? > > > > > > > > > > Dominic Cooney > > > > > > > > > > -----Original Message----- > > > > > From: Moderated discussion of advanced .NET topics. > > > > > [mailto:[EMAIL PROTECTED] On > Behalf Of Daniel > > > O'Connell > > > > > Sent: Thursday, 23 October 2003 9:05 AM > > > > > To: [EMAIL PROTECTED] > > > > > Subject: Re: [ADVANCED-DOTNET] C# generics constraints syntax > > > > > > > > > > I'd say readability first, personally. It'd be alot easier to > > > > > read > > > > > > > > > > public class Dictionary<KeyType,ValType> where KeyType : > IComparable, > > > > > ICollection, IAnotherThing, ValueType : IComparable, > IDictionaryValue, > > > > > IAnotherRestriction > > > > > > > > > > than > > > > > public class Dictionary<KeyType : IComparable, ICollection, > > > IAnotherThing, > > > > > ValueType : IComparable, IDictionaryValue, > IAnotherRestriction>; > > > > > > > > > > Beyond that, I imagine parsing is easier this way. It > would be > > > > > tough > > > to > > > > > determine what the second type name is, should it be named > > > ICollection, > > > > > IAnotherThing, ValueType, etc? > > > > > > > > > > ----- Original Message ----- > > > > > From: "Thong (Tum) Nguyen" <[EMAIL PROTECTED]> > > > > > To: <[EMAIL PROTECTED]> > > > > > Sent: Wednesday, October 22, 2003 5:50 PM > > > > > Subject: [ADVANCED-DOTNET] C# generics constraints syntax > > > > > > > > > > > > > > > > Hey folks, > > > > > > > > > > > > Can anyone think of a reason why the constraints > syntax is this: > > > > > > > > > > > > public class Dictionary<KeyType, ValType> where KeyType : > > > IComparable > > > > > > > > > > > > rather than this: > > > > > > > > > > > > public class Dictionary<KeyType : IComparable, ValType> > > > > > > > > > > > > ? > > > > > > > > > > > > The former adds an additional (unreserved?) keyword to the > language > > > and > > > > > > locates two related things apart from each other > (the generic > > > parameter > > > > > & > > > > > > its constraint). > > > > > > > > > > > > There's probably a good reason I've overlooked. > > > > > > > > > > > > All the best, > > > > > > > > > > > > ^Tum > > > > > > > > > > > > =================================== > > > > > > This list is hosted by DevelopMentorR > http://www.develop.com > > > > > > NEW! ASP.NET courses you may be interested in: > > > > > > > > > > > > 2 Days of ASP.NET, 29 Sept 2003, in Redmond > > > > > > http://www.develop.com/courses/2daspdotnet > > > > > > > > > > > > Guerrilla ASP.NET, 13 Oct 2003, in Boston > > > > > > http://www.develop.com/courses/gaspdotnet > > > > > > > > > > > > View archives and manage your subscription(s) at > > > > > http://discuss.develop.com > > > > > > > > > > =================================== > > > > > This list is hosted by DevelopMentorR http://www.develop.com > > > > > NEW! ASP.NET courses you may be interested in: > > > > > > > > > > 2 Days of ASP.NET, 29 Sept 2003, in Redmond > > > > > http://www.develop.com/courses/2daspdotnet > > > > > > > > > > Guerrilla ASP.NET, 13 Oct 2003, in Boston > > > > > http://www.develop.com/courses/gaspdotnet > > > > > > > > > > View archives and manage your subscription(s) at > > > > > http://discuss.develop.com > > > > > > > > > > =================================== > > > > > This list is hosted by DevelopMentor. http://www.develop.com > > > > > NEW! ASP.NET courses you may be interested in: > > > > > > > > > > 2 Days of ASP.NET, 29 Sept 2003, in Redmond > > > > > http://www.develop.com/courses/2daspdotnet > > > > > > > > > > Guerrilla ASP.NET, 13 Oct 2003, in Boston > > > > > http://www.develop.com/courses/gaspdotnet > > > > > > > > > > View archives and manage your subscription(s) at > > > > > http://discuss.develop.com > > > > > > > > =================================== > > > > This list is hosted by DevelopMentorR > http://www.develop.com NEW! > > > > ASP.NET courses you may be interested in: > > > > > > > > 2 Days of ASP.NET, 29 Sept 2003, in Redmond > > > > http://www.develop.com/courses/2daspdotnet > > > > > > > > Guerrilla ASP.NET, 13 Oct 2003, in Boston > > > > http://www.develop.com/courses/gaspdotnet > > > > > > > > View archives and manage your subscription(s) at > > > http://discuss.develop.com > > > > > > > > > > =================================== > > > This list is hosted by DevelopMentorR > http://www.develop.com NEW! > > > ASP.NET courses you may be interested in: > > > > > > 2 Days of ASP.NET, 29 Sept 2003, in Redmond > > > http://www.develop.com/courses/2daspdotnet > > > > > > Guerrilla ASP.NET, 13 Oct 2003, in Boston > > > http://www.develop.com/courses/gaspdotnet > > > > > > View archives and manage your subscription(s) at > > > http://discuss.develop.com > > > > =================================== > > This list is hosted by DevelopMentor(r) http://www.develop.com NEW! > > ASP.NET courses you may be interested in: > > > > 2 Days of ASP.NET, 29 Sept 2003, in Redmond > > http://www.develop.com/courses/2daspdotnet > > > > Guerrilla ASP.NET, 13 Oct 2003, in Boston > > http://www.develop.com/courses/gaspdotnet > > > > View archives and manage your subscription(s) at > http://discuss.develop.com > > =================================== > This list is hosted by DevelopMentor(r) http://www.develop.com > NEW! ASP.NET courses you may be interested in: > > 2 Days of ASP.NET, 29 Sept 2003, in Redmond > http://www.develop.com/courses/2daspdotnet > > Guerrilla ASP.NET, 13 Oct 2003, in Boston > http://www.develop.com/courses/gaspdotnet > > View archives and manage your subscription(s) at > http://discuss.develop.com > > =================================== This list is hosted by DevelopMentorŪ http://www.develop.com NEW! ASP.NET courses you may be interested in: 2 Days of ASP.NET, 29 Sept 2003, in Redmond http://www.develop.com/courses/2daspdotnet Guerrilla ASP.NET, 13 Oct 2003, in Boston http://www.develop.com/courses/gaspdotnet View archives and manage your subscription(s) at http://discuss.develop.com
