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Suggestion for C# language: Modification to the "new" keyword - Allow type inference in C# to use thfeedback/ratings/support (and while I loathe to say it, dissent) to a recommendation I am making for the C# language: https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=388649 Basically, it extends type inference to work with the left-hand side of an assignment, instead of the right. What I mean by that is if you use the right hand side, you have to use the "var" keyword, like so: var o = new object(); What I am proposing is something like this: object o = new(); There is a lot more to it, but that's the jist of it. For the complete details follow the link above. There is also post on my blog about it at (first is permalink): http://www.caspershouse.com/post.aspx?id=53b672b9-3b76-4027-802f-7a0d5ffeb7cd http://www.caspershouse.com/post/Called-out.aspx But it's not much more than a brief synopsis (like here) and a link to the feedback site. Thanks in advance. -- - Nicholas Paldino [.NET/C# MVP] - mvp@spam.guard.caspershouse.com "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard.caspershouse.com> wrote in Heh, I'm with you. See my response to the thread "Bitmpa.Save & GZipStream - message news:erc07ZJYJHA.2620@TK2MSFTNGP02.phx.gbl... > What I am proposing is something like this: > > object o = new(); error" started on 2008-12-13. Jeff,
Thanks for the support. If you like it, vote for it at the Microsoft Connect site. I've spoken with people internally about it, but that can be a little bit of a black hole. At least this documents it (and the support/dissent) in some way. -- Show quoteHide quote- Nicholas Paldino [.NET/C# MVP] - mvp@spam.guard.caspershouse.com "Jeff Johnson" <i.get@enough.spam> wrote in message news:e9utZcJYJHA.1188@TK2MSFTNGP05.phx.gbl... > "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard.caspershouse.com> wrote > in message news:erc07ZJYJHA.2620@TK2MSFTNGP02.phx.gbl... > >> What I am proposing is something like this: >> >> object o = new(); > > Heh, I'm with you. See my response to the thread "Bitmpa.Save & > GZipStream - error" started on 2008-12-13. > "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard.caspershouse.com> wrote in Voted. Plus I think you should change your blog post:message news:exPyeiJYJHA.5272@TK2MSFTNGP04.phx.gbl... > Thanks for the support. If you like it, vote for it at the Microsoft > Connect site. I've spoken with people internally about it, but that can > be a little bit of a black hole. At least this documents it (and the > support/dissent) in some way. ------------- To that end, I recommend the following. Whereas before type-inference used data from the right hand side in conjunction with the var keyword: var o = new object(); I suggest we should be able to do something like this: var o = new(); ------------- The second example should be object o = new(); Jeff,
Doh! Thanks. I edited that thing so many times I lost track. - Nick Show quoteHide quote "Jeff Johnson" <i.get@enough.spam> wrote in message news:uEPozpJYJHA.6000@TK2MSFTNGP05.phx.gbl... > "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard.caspershouse.com> wrote > in message news:exPyeiJYJHA.5272@TK2MSFTNGP04.phx.gbl... > >> Thanks for the support. If you like it, vote for it at the Microsoft >> Connect site. I've spoken with people internally about it, but that can >> be a little bit of a black hole. At least this documents it (and the >> support/dissent) in some way. > > Voted. Plus I think you should change your blog post: > > ------------- > To that end, I recommend the following. Whereas before type-inference > used data from the right hand side in conjunction with the var keyword: > > var o = new object(); > > I suggest we should be able to do something like this: > > var o = new(); > ------------- > > The second example should be > > object o = new(); > I prefer
var j = new ComplexJob(); Because SimpleJob j = new(); would create a SimpleJob, but I want a complex job. Using "var" gives you the short-hand you need (except it's 4 characters longer). I am undecided about your request. It neither excites me nor fills me with dread. It's just kind of... "meh" :-) Peter,
If you look at the full proposal at the Microsoft Connect site, you will see that it doesn't preclude you from using "var" if you want. It simply is an alternative with some extra benefits (there are uses outside of the areas that "var" is limited to now) that "var" doesn't give you when you want to use it for the purpose of being concise (as opposed to using it for an anonymous type). In regards to your second point, the same issue exists with "var" as it does with my proposal, you have no way of using polymorphism with either construct (I assume that ComplexJob derives from SimpleJob, or some other shared base). "var" will give you a type of ComplexJob, my proposal will give you a type of SimpleJob. -- Show quoteHide quote- Nicholas Paldino [.NET/C# MVP] - mvp@spam.guard.caspershouse.com "Peter Morris" <mrpmorrisNO@SPAMgmail.com> wrote in message news:ufLQnlJYJHA.5108@TK2MSFTNGP05.phx.gbl... >I prefer > > var j = new ComplexJob(); > > Because > > SimpleJob j = new(); > > would create a SimpleJob, but I want a complex job. Using "var" gives you > the short-hand you need (except it's 4 characters longer). I am undecided > about your request. It neither excites me nor fills me with dread. It's > just kind of... > > > "meh" :-) > > > > -- > Pete > ==== > http://mrpmorris.blogspot.com > http://www.capableobjects.com I was just kind of thinking out loud. I've given it some thought since and
I think it is a good solution to something that has always annoyed me about C#. SomeLongClassName c = new SomeLongClassName(); Introducing "var" made this more bearable var c = new SomeLongClassName(); but this isn't so clear when you are retrieving a result from a method var c = SomeOtherObject.SomeOtherMethod(); which is why I use an explicit name in such circumstances. I think your proposal is a much better solution in all cases (not that I have read the link). SomeLongClassName c = new(); Gives me the benefits and none of the disadvantages.
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"Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard.caspershouse.com> wrote in Sorry it doesn't get my vote.message news:erc07ZJYJHA.2620@TK2MSFTNGP02.phx.gbl... > If any of you have the time or inclination, I'd love > feedback/ratings/support (and while I loathe to say it, dissent) to a > recommendation I am making for the C# language: > > https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=388649 > > Basically, it extends type inference to work with the left-hand side of > an assignment, instead of the right. What I mean by that is if you use > the right hand side, you have to use the "var" keyword, like so: > > var o = new object(); > > What I am proposing is something like this: > > object o = new(); > > There is a lot more to it, but that's the jist of it. For the complete > details follow the link above. > > There is also post on my blog about it at (first is permalink): > > http://www.caspershouse.com/post.aspx?id=53b672b9-3b76-4027-802f-7a0d5ffeb7cd > http://www.caspershouse.com/post/Called-out.aspx > > But it's not much more than a brief synopsis (like here) and a link to > the feedback site. > The RHS is no longer independant of the LHS and that is just mathematically wrong. The other way round (as in the case of var) its fine. I'm also unclear on what actual problem is being solved by it. -- Anthony Jones - MVP ASP/ASP.NET Anthony,
The same issue exists with "var", so while it might not be mathematically correct, it is allowable in the language. When using "var", the left-hand side of the declaration is completely dependent on the right, it's the same issue, just reversed. Before "var", there was no dependency on either side. As for what problem it solves, it doesn't necessarily solve a problem (it's a recommendation/suggestion). I personally don't like the use of "var" for the purpose of being concise (as I believe it obfuscates the code), but that's a personal observation (and I believe it is a problem, but wouldn't argue the point, as I know it's pointless). It's a suggestion along the lines of "var" (when considering "var" on it's own, and not in conjunction with anonymous types) or auto-implemented properties (although this has the side effect of having an impact on the structure of the compiled code, in that it auto-generates the backing fields). -- Show quoteHide quote- Nicholas Paldino [.NET/C# MVP] - mvp@spam.guard.caspershouse.com "Anthony Jones" <AnthonyWJo***@yadayadayada.com> wrote in message news:e0lUIpJYJHA.5476@TK2MSFTNGP03.phx.gbl... > "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard.caspershouse.com> wrote > in message news:erc07ZJYJHA.2620@TK2MSFTNGP02.phx.gbl... >> If any of you have the time or inclination, I'd love >> feedback/ratings/support (and while I loathe to say it, dissent) to a >> recommendation I am making for the C# language: >> >> https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=388649 >> >> Basically, it extends type inference to work with the left-hand side >> of an assignment, instead of the right. What I mean by that is if you >> use the right hand side, you have to use the "var" keyword, like so: >> >> var o = new object(); >> >> What I am proposing is something like this: >> >> object o = new(); >> >> There is a lot more to it, but that's the jist of it. For the >> complete details follow the link above. >> >> There is also post on my blog about it at (first is permalink): >> >> http://www.caspershouse.com/post.aspx?id=53b672b9-3b76-4027-802f-7a0d5ffeb7cd >> http://www.caspershouse.com/post/Called-out.aspx >> >> But it's not much more than a brief synopsis (like here) and a link to >> the feedback site. >> > > Sorry it doesn't get my vote. > > The RHS is no longer independant of the LHS and that is just > mathematically wrong. The other way round (as in the case of var) its > fine. > > I'm also unclear on what actual problem is being solved by it. > > -- > Anthony Jones - MVP ASP/ASP.NET > "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard.caspershouse.com> wrote in The issue with var is different. We mathematically expect that with an message news:O3bTVuJYJHA.5312@TK2MSFTNGP02.phx.gbl... > Anthony, > > The same issue exists with "var", so while it might not be > mathematically correct, it is allowable in the language. > > When using "var", the left-hand side of the declaration is completely > dependent on the right, it's the same issue, just reversed. Before "var", > there was no dependency on either side. > equation like this:- x = a + b that x is impacted by the result of the RHS. We do not expect x to participate in anyway in the expression on the RHS. C# 3 allows x to be influenced not only by the value result of a specific invocation of an expression but its type is influenced by the expressions type as well. However the flow is in the same direction, RHS influences LHS but LHS has no part to play in the RHS. > As for what problem it solves, it doesn't necessarily solve a problem I do agree and I'm sure we've had a long thread here before on how liberally > (it's a recommendation/suggestion). I personally don't like the use of > "var" for the purpose of being concise (as I believe it obfuscates the > code), but that's a personal observation (and I believe it is a problem, > but wouldn't argue the point, as I know it's pointless). > var should be used. IMO var should primarily used for where the type of the RHS is an anonymous type. Idomatically its reasonable to use it as a result of a LINQ expression (even one where the type is known). The only other place I would use a var is in simple new operations:- var x = new Thing(); You seem to be proposing that we also be able to do this:- Thing x = new(); I don't see any improvement with this syntax. In fact it feels wrong because the flow of imformation is weird in fact so far to me its unique. Can you think of any other statement or expression where info flows from the RHS into LHS before the operation on the LHS can complete? -- Anthony Jones - MVP ASP/ASP.NET Anthony,
I can't think of a situation where info flows from the RHS into LHS before the operation on the LHS can complete. However, using your analogy, it could be said that there are situations where the LHS participates in the equation independently from the RHS. When you use polymorphism: IComparable<DateTime> dtComparable = new DateTime(2008, 12, 15); In this case, the LHS is contributing to what the range of values assigned to dtComparable can be (in this case, it expands the range to be anything implementing IComparable<DateTime> not just DateTime, as suggested by the RHS) independent of the RHS. Note that this was always the case (until "var" was introduced). The introduction of "var" was radically different, in that the barrier which kept each side from influencing the other (since you had to define the range of types on both sides) was broken down. The new proposal takes advantage of this fact that those barriers were broken down. Because of that previous segregation, I tend to look at this not in terms of an equation, but in terms of sets (which have no "sides"). With any declaration and assignment statement (like above) you have a set of types allowed on the LHS and RHS. If there is an intersection between the sets, then the assignment is valid. Things like my proposal, "var", even polymorphism just change the range of the set. In that sense, as long as there is an intersection of sets, it doesn't matter what side either is on. -- Show quoteHide quote- Nicholas Paldino [.NET/C# MVP] - mvp@spam.guard.caspershouse.com "Anthony Jones" <AnthonyWJo***@yadayadayada.com> wrote in message news:OBd$YHPYJHA.5020@TK2MSFTNGP03.phx.gbl... > "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard.caspershouse.com> wrote > in message news:O3bTVuJYJHA.5312@TK2MSFTNGP02.phx.gbl... >> Anthony, >> >> The same issue exists with "var", so while it might not be >> mathematically correct, it is allowable in the language. >> >> When using "var", the left-hand side of the declaration is completely >> dependent on the right, it's the same issue, just reversed. Before >> "var", there was no dependency on either side. >> > > The issue with var is different. We mathematically expect that with an > equation like this:- > > x = a + b > > that x is impacted by the result of the RHS. We do not expect x to > participate in anyway in the expression on the RHS. C# 3 allows x to be > influenced not only by the value result of a specific invocation of an > expression but its type is influenced by the expressions type as well. > However the flow is in the same direction, RHS influences LHS but LHS has > no part to play in the RHS. > > >> As for what problem it solves, it doesn't necessarily solve a problem >> (it's a recommendation/suggestion). I personally don't like the use of >> "var" for the purpose of being concise (as I believe it obfuscates the >> code), but that's a personal observation (and I believe it is a problem, >> but wouldn't argue the point, as I know it's pointless). >> > > I do agree and I'm sure we've had a long thread here before on how > liberally var should be used. IMO var should primarily used for where the > type of the RHS is an anonymous type. Idomatically its reasonable to use > it as a result of a LINQ expression (even one where the type is known). > The only other place I would use a var is in simple new operations:- > > var x = new Thing(); > > You seem to be proposing that we also be able to do this:- > > Thing x = new(); > > I don't see any improvement with this syntax. In fact it feels wrong > because the flow of imformation is weird in fact so far to me its unique. > Can you think of any other statement or expression where info flows from > the RHS into LHS before the operation on the LHS can complete? > > > -- > Anthony Jones - MVP ASP/ASP.NET > "Anthony Jones" <AnthonyWJo***@yadayadayada.com> wrote in message The problem is "unnecessary wordiness."news:e0lUIpJYJHA.5476@TK2MSFTNGP03.phx.gbl... > Sorry it doesn't get my vote. > > The RHS is no longer independant of the LHS and that is just > mathematically wrong. The other way round (as in the case of var) its > fine. > > I'm also unclear on what actual problem is being solved by it. Why oh why must you write MyClass TWICE: MyClass c = new MyClass(); when you could just do MyClass c = new(); Nothing in the proposal STOPS you from using the full syntax, and you would HAVE to use it if you wanted to assign a derived class: MyClass c = new MyNewClassDerivedFromMyClass(); but it serves as a less-cluttered shorthand. There aren't many cases where I think VB.NET has an advantage over C#, but this syntax is one of them, because there you can already do this: Dim c As New MyClass(); and you've got a constructed instance without writing MyClass twice. You can go the long way as well, especially for derivatives: Dim c As MyClass = New MyNewClassDerivedFromMyClass() Jeff Johnson wrote:
> There aren't many cases Isn't that the VB equivalent of> where I think VB.NET has an advantage over C#, but this syntax is one > of them, because there you can already do this: > > Dim c As New MyClass(); var c = new MyClass(); which is already supported by C#? -- Rudy Velthuis http://rvelthuis.de "If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy." -- James Madison
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"Rudy Velthuis" <newsgro***@rvelthuis.de> wrote in message Ah, I see the opposition now. I guess it comes down to the fact that I hate news:xn0fz1yh0a1ok2g00u@news.microsoft.com... >> There aren't many cases >> where I think VB.NET has an advantage over C#, but this syntax is one >> of them, because there you can already do this: >> >> Dim c As New MyClass(); > > Isn't that the VB equivalent of > > var c = new MyClass(); > > which is already supported by C#? "var" and think it's ugly, makes code harder to read, and will be highly abused, whereas I think "object o = new()" looks very nice.
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"Jeff Johnson" <i.get@enough.spam> wrote in message Seriously you find this:-news:%23s9pNFKYJHA.556@TK2MSFTNGP06.phx.gbl... > "Rudy Velthuis" <newsgro***@rvelthuis.de> wrote in message > news:xn0fz1yh0a1ok2g00u@news.microsoft.com... > >>> There aren't many cases >>> where I think VB.NET has an advantage over C#, but this syntax is one >>> of them, because there you can already do this: >>> >>> Dim c As New MyClass(); >> >> Isn't that the VB equivalent of >> >> var c = new MyClass(); >> >> which is already supported by C#? > > Ah, I see the opposition now. I guess it comes down to the fact that I > hate "var" and think it's ugly, makes code harder to read, and will be > highly abused, whereas I think "object o = new()" looks very nice. MyClass c = new(); Easier to read than var x = new MyClass(); ? -- Anthony Jones - MVP ASP/ASP.NET
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"Anthony Jones" <AnthonyWJo***@yadayadayada.com> wrote in message 100% seriously. Here's why: the new (no pun intended) method is consistent. news:ueuluKPYJHA.4596@TK2MSFTNGP06.phx.gbl... >> Ah, I see the opposition now. I guess it comes down to the fact that I >> hate "var" and think it's ugly, makes code harder to read, and will be >> highly abused, whereas I think "object o = new()" looks very nice. > > Seriously you find this:- > > MyClass c = new(); > > Easier to read than > > var x = new MyClass(); > > ? If I want to declare a variable of BaseClass and set it to a derived class, I can't use var: var x = new BaseClass(); I get a BaseClass, so I must change the syntax to BaseClass x = new DerivedClass(); So now the code is mixed, like this: var x = new BaseClass(); var y = new Whatever(); BaseClass z = new DerivedClass(); but with the other method, it's consistent: BaseClass x = new(); Whatever y = new(); BaseClass z = new DerivedClass(); You ALWAYS declare the class on the LHS. Anthony Jones <AnthonyWJo***@yadayadayada.com> wrote:
> Seriously you find this:- I'm not Jeff, but yeah. Completely. > > MyClass c = new(); > > Easier to read than > > var x = new MyClass(); The type is declared, a variable is allocated, and a new object of the type is created and assigned to the variable. It feels completely natural. While I know what var does, it looks like late binding. This creates a slight pause where I have to stop, focus on what language I'm using and decide, no this isn't late binding, it's an alternate syntax for declaring the type. -- J.B. Moreno Jeff Johnson wrote:
> >> Dim c As New MyClass(); I often use Delphi, so I'm used to it. "Dim", OTOH, is plain ugly, IMO.> > > > Isn't that the VB equivalent of > > > > var c = new MyClass(); > > > > which is already supported by C#? > > Ah, I see the opposition now. I guess it comes down to the fact that > I hate "var" and think it's ugly <g> -- Rudy Velthuis http://rvelthuis.de "In America, anybody can be president. That's one of the risks you take." -- Adlai Stevenson (1900-1965)
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"Jeff Johnson" <i.get@enough.spam> wrote: This would be an OK idea if "= new()" were a single operator. The problem>"Anthony Jones" <AnthonyWJo***@yadayadayada.com> wrote in message >news:e0lUIpJYJHA.5476@TK2MSFTNGP03.phx.gbl... > >> Sorry it doesn't get my vote. >> >> The RHS is no longer independant of the LHS and that is just >> mathematically wrong. The other way round (as in the case of var) its >> fine. >> >> I'm also unclear on what actual problem is being solved by it. > >The problem is "unnecessary wordiness." > >Why oh why must you write MyClass TWICE: > > MyClass c = new MyClass(); > >when you could just do > > MyClass c = new(); with this proposal, as I see it, is that "new" is a general-purpose operator that can be used in other ways. What you are proposing requires an ugly and intrusive change to the expression parser. Right now, the parser sees this: LHS = RHS; It is then able to evaluate the RHS using normal expression parsing, then evaluate the LHS using the lvalue parsing, and connect them together with an assignment Your change would require special-casing to say IF this is an assignment statement AND the left hand side declares a new variable of type X AND the right side consists only of a "new operator" THEN assume that the "new" operator should create a type X". That's very intrusive, and I'd be surprised if there were any single spot within the compiler to insert this. -- Tim Roberts, t***@probo.com Providenza & Boekelheide, Inc. On Wed, 17 Dec 2008 23:07:45 -0800, Tim Roberts <t***@probo.com> wrote:
> [...] The compiler is already doing something similar with the "var" keyword. > Your change would require special-casing to say > IF this is an assignment statement > AND the left hand side declares a new variable of type X > AND the right side consists only of a "new operator" > THEN assume that the "new" operator should create a type X". > > That's very intrusive, and I'd be surprised if there were any single spot > within the compiler to insert this. That is, it causes the type of the initialized variable to simply be exactly that of the RHS of the initialization. It may well be that the compiler special-cases variable declarations differently from general assignments and in doing so, it's not that big of a deal do implement "var". But if so, I would expect it would also not be a big deal to implement Nicholas's suggestion, so long as it was restricted to initializers, rather than just arbitrary assignments. Pete Well... for one, this is annoying...
var query = new Query(); Results results = query.Execute(); Customer cust = null; if ( results.Count > 0 ) { cust = results[0]; } Chunks of inconsistency like that make me instinctively avoid the use of var. In VB at least all of the type names are to the right of the variable name. PS: Please don't suggest FirstOrDefault() because that's not the point. :) Show quoteHide quote "Anthony Jones" <AnthonyWJo***@yadayadayada.com> wrote in message news:e0lUIpJYJHA.5476@TK2MSFTNGP03.phx.gbl... > "Nicholas Paldino [.NET/C# MVP]" <mvp@spam.guard.caspershouse.com> wrote > in message news:erc07ZJYJHA.2620@TK2MSFTNGP02.phx.gbl... >> If any of you have the time or inclination, I'd love >> feedback/ratings/support (and while I loathe to say it, dissent) to a >> recommendation I am making for the C# language: >> >> https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=388649 >> >> Basically, it extends type inference to work with the left-hand side >> of an assignment, instead of the right. What I mean by that is if you >> use the right hand side, you have to use the "var" keyword, like so: >> >> var o = new object(); >> >> What I am proposing is something like this: >> >> object o = new(); >> >> There is a lot more to it, but that's the jist of it. For the >> complete details follow the link above. >> >> There is also post on my blog about it at (first is permalink): >> >> http://www.caspershouse.com/post.aspx?id=53b672b9-3b76-4027-802f-7a0d5ffeb7cd >> http://www.caspershouse.com/post/Called-out.aspx >> >> But it's not much more than a brief synopsis (like here) and a link to >> the feedback site. >> > > Sorry it doesn't get my vote. > > The RHS is no longer independant of the LHS and that is just > mathematically wrong. The other way round (as in the case of var) its > fine. > > I'm also unclear on what actual problem is being solved by it. > > -- > Anthony Jones - MVP ASP/ASP.NET >  
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