digitalmars.D.learn - auto
- Hoenir (3/3) Jun 20 2007 I still can't get the purpose of "auto".
- Derek Parnell (7/10) Jun 20 2007 auto y = someFunc(); // What type is it now?
- Ary Manzana (2/11) Jun 20 2007 // What can you do with y now, if you don't know the type?
- BCS (9/21) Jun 20 2007 whatever you want
- Derek Parnell (12/23) Jun 20 2007 Pass it to a function that does know its type.
- Bill Baxter (17/31) Jun 21 2007 I *think* the point was just that the code becomes less readable without...
- Frits van Bommel (7/9) Jun 22 2007 [list]
- Ary Manzana (6/42) Jun 22 2007 Thanks for this! This is exacly my thought, although I couldn't have
- mwarning (6/9) Jun 20 2007 "auto" is very usefull for cases like:
- Jari-Matti =?ISO-8859-1?Q?M=E4kel=E4?= (7/10) Jun 20 2007 One day you may want to write
- Jarrett Billingsley (7/10) Jun 20 2007 I agree in this case, and I think some people get a little
- Hoenir (2/8) Jun 20 2007 I see. This makes sense. Thank you all. :)
- janderson (8/11) Jun 21 2007 Its a generic/maintainable way of programming. It means you can change
- janderson (5/19) Jun 21 2007 I should add, in the same vain (as others have mentioned in other ways),...
I still can't get the purpose of "auto". I know it makes it possible to e.g. write "auto y = 4u;" but why not just "uint y = 4;"?
Jun 20 2007
On Wed, 20 Jun 2007 14:20:43 +0200, Hoenir wrote:I still can't get the purpose of "auto". I know it makes it possible to e.g. write "auto y = 4u;" but why not just "uint y = 4;"?auto y = someFunc(); // What type is it now? -- Derek Parnell Melbourne, Australia "Justice for David Hicks!" skype: derek.j.parnell
Jun 20 2007
Derek Parnell escribió:On Wed, 20 Jun 2007 14:20:43 +0200, Hoenir wrote:// What can you do with y now, if you don't know the type?I still can't get the purpose of "auto". I know it makes it possible to e.g. write "auto y = 4u;" but why not just "uint y = 4;"?auto y = someFunc(); // What type is it now?
Jun 20 2007
BCS <BCS pathlink.com> Ary Manzana wrote:Derek Parnell escribió:whatever you want auto z = y * 2; auto x = z*y; return x + y + z; With a little care and a working knowledge of the typing rules of expressions you can get a lot done without ever using a actual type. This is of a lot of use if you are doing template code where you really can't known the type until compile time.On Wed, 20 Jun 2007 14:20:43 +0200, Hoenir wrote:// What can you do with y now, if you don't know the type?I still can't get the purpose of "auto". I know it makes it possible to e.g. write "auto y = 4u;" but why not just "uint y = 4;"?auto y = someFunc(); // What type is it now?
Jun 20 2007
On Wed, 20 Jun 2007 21:37:44 -0200, Ary Manzana wrote:Derek Parnell escribió:Pass it to a function that does know its type. void funcA(int X) { } void funcA(float X) { } void funcA(char[] X) { } auto y = someFunc(); funcA(y); -- Derek (skype: derek.j.parnell) Melbourne, Australia 21/06/2007 12:30:47 PMOn Wed, 20 Jun 2007 14:20:43 +0200, Hoenir wrote:// What can you do with y now, if you don't know the type?I still can't get the purpose of "auto". I know it makes it possible to e.g. write "auto y = 4u;" but why not just "uint y = 4;"?auto y = someFunc(); // What type is it now?
Jun 20 2007
Derek Parnell wrote:On Wed, 20 Jun 2007 21:37:44 -0200, Ary Manzana wrote:I *think* the point was just that the code becomes less readable without any obvious indication of what type you've got. Sure you can do all the same things you could do it the type were explicit, but someone else asked to fix this code is going to have to track down "someFunc()" to see what it returns. Lacking any particular extenuating circumstances, I agree that that making types explicit is better than using auto. But auto makes sense when 1) the actual type is a built-in (auto x = foo.length) 2) the actual type is obvious (auto x = new MyClass()) 3) the actual type is huge/untypeable like ( Node!(Node!(Node!(Expr!(Terminal!(1),Terminal!(2))))) x = expr!(); 4) the actual type is unknowable (some template usages) or 5) when you're in a real hurry and don't have time to figure out what the actual type is. :-) --bbDerek Parnell escribió:Pass it to a function that does know its type.On Wed, 20 Jun 2007 14:20:43 +0200, Hoenir wrote:// What can you do with y now, if you don't know the type?I still can't get the purpose of "auto". I know it makes it possible to e.g. write "auto y = 4u;" but why not just "uint y = 4;"?auto y = someFunc(); // What type is it now?
Jun 21 2007
Bill Baxter wrote:Lacking any particular extenuating circumstances, I agree that that making types explicit is better than using auto. But auto makes sense when[list] How about: 6) When the actual type may change later, and you want to make sure the variable is of the right type? I've often found this to be very useful, especially since some implicit conversions can change the value (e.g. long -> int, signed/unsigned).
Jun 22 2007
Bill Baxter escribió:Derek Parnell wrote:Thanks for this! This is exacly my thought, although I couldn't have expressed myself that well. I also agree with the situations you describe below, and also with number 6 of Frits. I'll not use it anywhere else, since having the type is more self documenting in a function.On Wed, 20 Jun 2007 21:37:44 -0200, Ary Manzana wrote:I *think* the point was just that the code becomes less readable without any obvious indication of what type you've got. Sure you can do all the same things you could do it the type were explicit, but someone else asked to fix this code is going to have to track down "someFunc()" to see what it returns.Derek Parnell escribió:Pass it to a function that does know its type.On Wed, 20 Jun 2007 14:20:43 +0200, Hoenir wrote:// What can you do with y now, if you don't know the type?I still can't get the purpose of "auto". I know it makes it possible to e.g. write "auto y = 4u;" but why not just "uint y = 4;"?auto y = someFunc(); // What type is it now?Lacking any particular extenuating circumstances, I agree that that making types explicit is better than using auto. But auto makes sense when 1) the actual type is a built-in (auto x = foo.length) 2) the actual type is obvious (auto x = new MyClass()) 3) the actual type is huge/untypeable like ( Node!(Node!(Node!(Expr!(Terminal!(1),Terminal!(2))))) x = expr!(); 4) the actual type is unknowable (some template usages) or 5) when you're in a real hurry and don't have time to figure out what the actual type is. :-) --bb
Jun 22 2007
Hoenir Wrote:I still can't get the purpose of "auto". I know it makes it possible to e.g. write "auto y = 4u;" but why not just "uint y = 4;"?"auto" is very usefull for cases like: auto x = new MyNewClass!(Foo, Bar)(); or auto y = getSomething(); doSmomething(y);
Jun 20 2007
Hoenir wrote:I still can't get the purpose of "auto". I know it makes it possible to e.g. write "auto y = 4u;" but why not just "uint y = 4;"?One day you may want to write class foo(a = int, b = int) { } void main() { auto bar = new foo!(foo!( foo!(foo!(), foo!()), foo!(foo!(), foo!()) ), foo!(foo!(), foo!())); }
Jun 20 2007
"Hoenir" <mrmocool gmx.de> wrote in message news:f5b64b$1aeq$1 digitalmars.com...I still can't get the purpose of "auto". I know it makes it possible to e.g. write "auto y = 4u;" but why not just "uint y = 4;"?I agree in this case, and I think some people get a little type-inference-happy. But it's very useful in the cases that Derek and mwarning have posted, and I use it a lot in templates as well (rather than picking apart a complex type to determine the correct type for a variable, just use auto).
Jun 20 2007
Jarrett Billingsley wrote:I agree in this case, and I think some people get a little type-inference-happy. But it's very useful in the cases that Derek and mwarning have posted, and I use it a lot in templates as well (rather than picking apart a complex type to determine the correct type for a variable, just use auto).I see. This makes sense. Thank you all. :)
Jun 20 2007
Hoenir wrote:I still can't get the purpose of "auto". I know it makes it possible to e.g. write "auto y = 4u;" but why not just "uint y = 4;"?Its a generic/maintainable way of programming. It means you can change the types your using without having to change ever reference to it. It means you can copy paste or template a piece of code and have it work with little change. It gets even more useful in larger programs when you start to layer this sort of general programming. I hope that helps.
Jun 21 2007
janderson wrote:Hoenir wrote:I should add, in the same vain (as others have mentioned in other ways), its useful for creating code that will work even when someone changes the interface. -JoelI still can't get the purpose of "auto". I know it makes it possible to e.g. write "auto y = 4u;" but why not just "uint y = 4;"?Its a generic/maintainable way of programming. It means you can change the types your using without having to change ever reference to it. It means you can copy paste or template a piece of code and have it work with little change. It gets even more useful in larger programs when you start to layer this sort of general programming. I hope that helps.
Jun 21 2007