digitalmars.D.learn - Return types of the methods of a struct
- Quentin Ladeveze (5/5) Jun 19 2015 Hi,
- Quentin Ladeveze (2/7) Jun 19 2015 Hum. How can I delete a post ?
- Steven Schveighoffer (4/13) Jun 19 2015 You can't. The forum is backed by a newsgroup, just post the full
- Quentin Ladeveze (23/38) Jun 19 2015 Thank you :)
- Steven Schveighoffer (4/41) Jun 19 2015 Does this work for you, or is there a further expectation?
- Quentin Ladeveze (8/12) Jun 19 2015 In fact, I was trying to use traits to create the tuple
- Baz (5/20) Jun 19 2015 when the return type is defined inside the function it's called a
- Steven Schveighoffer (4/23) Jun 19 2015 Actually, this isn't a voldemort type, because the type can be named
- Daniel =?UTF-8?B?S296w6Fr?= via Digitalmars-d-learn (5/22) Jun 19 2015 On Fri, 19 Jun 2015 13:52:52 +0000
- Quentin Ladeveze (3/26) Jun 19 2015 These are interesting and can be useful, but allMembers returns
- Steven Schveighoffer (10/35) Jun 19 2015 It's a *compile time* string. D is able to do some amazing things with
- Quentin Ladeveze (11/51) Jun 19 2015 I would never have thought about mixins, this is amazing ! But
- Steven Schveighoffer (20/70) Jun 19 2015 The string must stay compile time. This means it must be calculated:
- ZombineDev (3/6) Jun 19 2015 Here's my solution:
- Quentin Ladeveze (2/8) Jun 19 2015 Thank you very much, this solution is interesting too.
- Baz (3/33) Jun 19 2015 in the declaration set the return type to 'auto'.
- Baz (3/41) Jun 19 2015 Ah, damn, haven't see Steven Schveighoffer answer while i was
- Justin Whear (5/14) Jun 19 2015 You'll want to work your way through this example carefully as it's
- Quentin Ladeveze (3/19) Jun 19 2015 This is interesting, thank you very much ! I will try to figure
Hi, I have a struct with some methods int it, let's say ``` struct Example{ int intValue(){
Jun 19 2015
On Friday, 19 June 2015 at 13:12:08 UTC, Quentin Ladeveze wrote:Hi, I have a struct with some methods int it, let's say ``` struct Example{ int intValue(){Hum. How can I delete a post ?
Jun 19 2015
On 6/19/15 9:13 AM, Quentin Ladeveze wrote:On Friday, 19 June 2015 at 13:12:08 UTC, Quentin Ladeveze wrote:You can't. The forum is backed by a newsgroup, just post the full corrected version :) -SteveHi, I have a struct with some methods int it, let's say ``` struct Example{ int intValue(){Hum. How can I delete a post ?
Jun 19 2015
On Friday, 19 June 2015 at 13:26:03 UTC, Steven Schveighoffer wrote:On 6/19/15 9:13 AM, Quentin Ladeveze wrote:Thank you :) Here is th corrected version : Hi, I have a struct with some methods int it, let's say ``` struct Example{ int a(){ return someValue; } float b(){ return someOtherValue; } string stringValue(){ return c; } } Is there any way to have a asTuple method in this struct that would returns something like : Tuple!(int, "a", float, "b", string, "c") and that will contain the values of the methods of the struct ? Thanks.On Friday, 19 June 2015 at 13:12:08 UTC, Quentin Ladeveze wrote:You can't. The forum is backed by a newsgroup, just post the full corrected version :) -SteveHi, I have a struct with some methods int it, let's say ``` struct Example{ int intValue(){Hum. How can I delete a post ?
Jun 19 2015
On 6/19/15 9:27 AM, Quentin Ladeveze wrote:On Friday, 19 June 2015 at 13:26:03 UTC, Steven Schveighoffer wrote:Does this work for you, or is there a further expectation? auto asTuple() { return Tuple!(int, "a", ...)(a, b, stringValue);} -SteveOn 6/19/15 9:13 AM, Quentin Ladeveze wrote:Thank you :) Here is th corrected version : Hi, I have a struct with some methods int it, let's say ``` struct Example{ int a(){ return someValue; } float b(){ return someOtherValue; } string stringValue(){ return c; } } Is there any way to have a asTuple method in this struct that would returns something like : Tuple!(int, "a", float, "b", string, "c") and that will contain the values of the methods of the struct ?On Friday, 19 June 2015 at 13:12:08 UTC, Quentin Ladeveze wrote:You can't. The forum is backed by a newsgroup, just post the full corrected version :) -SteveHi, I have a struct with some methods int it, let's say ``` struct Example{ int intValue(){Hum. How can I delete a post ?
Jun 19 2015
On Friday, 19 June 2015 at 13:38:45 UTC, Steven Schveighoffer wrote:Does this work for you, or is there a further expectation? auto asTuple() { return Tuple!(int, "a", ...)(a, b, stringValue);} -SteveIn fact, I was trying to use traits to create the tuple automatically and being able to add or remove methods to the struct without breaking the asTuple method. I used allMembers for the name of the methods, but I didn't found anything for their return types or their values. Thank you.
Jun 19 2015
On Friday, 19 June 2015 at 13:52:54 UTC, Quentin Ladeveze wrote:On Friday, 19 June 2015 at 13:38:45 UTC, Steven Schveighoffer wrote:when the return type is defined inside the function it's called a 'Voldemort type', see http://www.drdobbs.com/cpp/voldemort-types-in-d/232901591?pgno=2Does this work for you, or is there a further expectation? auto asTuple() { return Tuple!(int, "a", ...)(a, b, stringValue);} -SteveIn fact, I was trying to use traits to create the tuple automatically and being able to add or remove methods to the struct without breaking the asTuple method. I used allMembers for the name of the methods, but I didn't found anything for their return types or their values. Thank you.
Jun 19 2015
On 6/19/15 10:01 AM, Baz wrote:On Friday, 19 June 2015 at 13:52:54 UTC, Quentin Ladeveze wrote:Actually, this isn't a voldemort type, because the type can be named outside the function. -SteveOn Friday, 19 June 2015 at 13:38:45 UTC, Steven Schveighoffer wrote:when the return type is defined inside the function it's called a 'Voldemort type', see http://www.drdobbs.com/cpp/voldemort-types-in-d/232901591?pgno=2Does this work for you, or is there a further expectation? auto asTuple() { return Tuple!(int, "a", ...)(a, b, stringValue);} -SteveIn fact, I was trying to use traits to create the tuple automatically and being able to add or remove methods to the struct without breaking the asTuple method. I used allMembers for the name of the methods, but I didn't found anything for their return types or their values. Thank you.
Jun 19 2015
On Fri, 19 Jun 2015 13:52:52 +0000 Quentin Ladeveze via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> wrote:On Friday, 19 June 2015 at 13:38:45 UTC, Steven Schveighoffer wrote:http://dlang.org/phobos/std_traits.html#ReturnType http://dlang.org/phobos/std_traits.html#ParameterTypeTupleDoes this work for you, or is there a further expectation? auto asTuple() { return Tuple!(int, "a", ...)(a, b, stringValue);} -SteveIn fact, I was trying to use traits to create the tuple automatically and being able to add or remove methods to the struct without breaking the asTuple method. I used allMembers for the name of the methods, but I didn't found anything for their return types or their values. Thank you.
Jun 19 2015
On Friday, 19 June 2015 at 14:04:05 UTC, Daniel Kozák wrote:On Fri, 19 Jun 2015 13:52:52 +0000 Quentin Ladeveze via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> wrote:These are interesting and can be useful, but allMembers returns strings and not functions, so I can't apply ReturnType.On Friday, 19 June 2015 at 13:38:45 UTC, Steven Schveighoffer wrote:http://dlang.org/phobos/std_traits.html#ReturnType http://dlang.org/phobos/std_traits.html#ParameterTypeTupleDoes this work for you, or is there a further expectation? auto asTuple() { return Tuple!(int, "a", ...)(a, b, stringValue);} -SteveIn fact, I was trying to use traits to create the tuple automatically and being able to add or remove methods to the struct without breaking the asTuple method. I used allMembers for the name of the methods, but I didn't found anything for their return types or their values. Thank you.
Jun 19 2015
On 6/19/15 10:13 AM, Quentin Ladeveze wrote:On Friday, 19 June 2015 at 14:04:05 UTC, Daniel Kozák wrote:It's a *compile time* string. D is able to do some amazing things with this :) // assuming 'a' is the first member mixin("alias aReturnType = ReturnType!(Example." ~ __traits(allMembers, Example)[0] ~ ");"); static assert(is(aReturnType == int)); Using foreach over allMembers, you can construct a perfect return tuple using introspection and mixin. -SteveOn Fri, 19 Jun 2015 13:52:52 +0000 Quentin Ladeveze via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> wrote:These are interesting and can be useful, but allMembers returns strings and not functions, so I can't apply ReturnType.On Friday, 19 June 2015 at 13:38:45 UTC, Steven Schveighoffer wrote:http://dlang.org/phobos/std_traits.html#ReturnType http://dlang.org/phobos/std_traits.html#ParameterTypeTupleDoes this work for you, or is there a further expectation? auto asTuple() { return Tuple!(int, "a", ...)(a, b, > stringValue);} -SteveIn fact, I was trying to use traits to create the tuple automatically and being able to add or remove methods to the struct without breaking the asTuple method. I used allMembers for the name of the methods, but I didn't found anything for their return types or their values. Thank you.
Jun 19 2015
On Friday, 19 June 2015 at 14:42:59 UTC, Steven Schveighoffer wrote:On 6/19/15 10:13 AM, Quentin Ladeveze wrote:I would never have thought about mixins, this is amazing ! But thinking at compile time still is a little difficult for me, and now I don't understand how you can construct your tuple. I've been trying to create a string, by iterating on allMembers and concatenating the result of my functions in a string. But of course, I cannot use this string at compile time. Now I know there is a way t do it, but my brain just can't figure it out. Can you help me ?On Friday, 19 June 2015 at 14:04:05 UTC, Daniel Kozák wrote:It's a *compile time* string. D is able to do some amazing things with this :) // assuming 'a' is the first member mixin("alias aReturnType = ReturnType!(Example." ~ __traits(allMembers, Example)[0] ~ ");"); static assert(is(aReturnType == int)); Using foreach over allMembers, you can construct a perfect return tuple using introspection and mixin. -SteveOn Fri, 19 Jun 2015 13:52:52 +0000 Quentin Ladeveze via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> wrote:These are interesting and can be useful, but allMembers returns strings and not functions, so I can't apply ReturnType.On Friday, 19 June 2015 at 13:38:45 UTC, Steven Schveighoffer wrote:http://dlang.org/phobos/std_traits.html#ReturnType http://dlang.org/phobos/std_traits.html#ParameterTypeTupleDoes this work for you, or is there a further expectation? auto asTuple() { return Tuple!(int, "a", ...)(a, b, > stringValue);} -SteveIn fact, I was trying to use traits to create the tuple automatically and being able to add or remove methods to the struct without breaking the asTuple method. I used allMembers for the name of the methods, but I didn't found anything for their return types or their values. Thank you.
Jun 19 2015
On 6/19/15 12:09 PM, Quentin Ladeveze wrote:On Friday, 19 June 2015 at 14:42:59 UTC, Steven Schveighoffer wrote:The string must stay compile time. This means it must be calculated: 1. in a mixin statement Example is what I wrote earlier. 2. as an initializer to an immutable, enum, or non-local variable enum x = "Blah." ~ __traits(allMembers, Blah)[0]; // x is compile-time 3. inside a CTFE function. A CTFE function is just a normal runtime function with restrictions (see http://dlang.org/function.html#interpretation). But you must *call* it from a context like 1 or 2: string foo(string a, string b) { return a ~ b; } // foo is CTFEable auto x1 = foo("a", "b"); // x1 is a runtime string, foo is called at runtime enum x2 = foo("a", "b"); // x2 is a compile-time string, foo is executed at compile time (it is not called during execution of your program mixin("int " ~ x1 ~ ";"); // error, can't use runtime string x1 mixin("int " ~ x2 ~ ";"); // ok, declares int ab; mixin("int " ~ foo("c", "d") ~ ";"); // ok, declares int ab; Keep your code all executing at compile time, and you can use your strings to write your code for you! -SteveOn 6/19/15 10:13 AM, Quentin Ladeveze wrote:I would never have thought about mixins, this is amazing ! But thinking at compile time still is a little difficult for me, and now I don't understand how you can construct your tuple. I've been trying to create a string, by iterating on allMembers and concatenating the result of my functions in a string. But of course, I cannot use this string at compile time. Now I know there is a way t do it, but my brain just can't figure it out. Can you help me ?On Friday, 19 June 2015 at 14:04:05 UTC, Daniel Kozák wrote:It's a *compile time* string. D is able to do some amazing things with this :) // assuming 'a' is the first member mixin("alias aReturnType = ReturnType!(Example." ~ __traits(allMembers, Example)[0] ~ ");"); static assert(is(aReturnType == int)); Using foreach over allMembers, you can construct a perfect return tuple using introspection and mixin. -SteveOn Fri, 19 Jun 2015 13:52:52 +0000 Quentin Ladeveze via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> wrote:These are interesting and can be useful, but allMembers returns strings and not functions, so I can't apply ReturnType.On Friday, 19 June 2015 at 13:38:45 UTC, Steven Schveighoffer wrote:http://dlang.org/phobos/std_traits.html#ReturnType http://dlang.org/phobos/std_traits.html#ParameterTypeTupleDoes this work for you, or is there a further expectation? auto asTuple() { return Tuple!(int, "a", ...)(a, b, > >stringValue);}-SteveIn fact, I was trying to use traits to create the tuple automatically and being able to add or remove methods to the struct without breaking the asTuple method. I used allMembers for the name of the methods, but I didn't found anything for their return types or their values. Thank you.
Jun 19 2015
On Friday, 19 June 2015 at 14:13:46 UTC, Quentin Ladeveze wrote:Here's my solution: http://dpaste.dzfl.pl/c69de3c16d75[..]These are interesting and can be useful, but allMembers returns strings and not functions, so I can't apply ReturnType.
Jun 19 2015
On Friday, 19 June 2015 at 15:47:09 UTC, ZombineDev wrote:On Friday, 19 June 2015 at 14:13:46 UTC, Quentin Ladeveze wrote:Thank you very much, this solution is interesting too.Here's my solution: http://dpaste.dzfl.pl/c69de3c16d75[..]These are interesting and can be useful, but allMembers returns strings and not functions, so I can't apply ReturnType.
Jun 19 2015
On Friday, 19 June 2015 at 13:27:15 UTC, Quentin Ladeveze wrote:On Friday, 19 June 2015 at 13:26:03 UTC, Steven Schveighoffer wrote:in the declaration set the return type to 'auto'. Use 'tuple' instead of 'Tuple'.On 6/19/15 9:13 AM, Quentin Ladeveze wrote:Thank you :) Here is th corrected version : Hi, I have a struct with some methods int it, let's say ``` struct Example{ int a(){ return someValue; } float b(){ return someOtherValue; } string stringValue(){ return c; } } Is there any way to have a asTuple method in this struct that would returns something like : Tuple!(int, "a", float, "b", string, "c") and that will contain the values of the methods of the struct ? Thanks.[...]You can't. The forum is backed by a newsgroup, just post the full corrected version :) -Steve
Jun 19 2015
On Friday, 19 June 2015 at 13:40:01 UTC, Baz wrote:On Friday, 19 June 2015 at 13:27:15 UTC, Quentin Ladeveze wrote:Ah, damn, haven't see Steven Schveighoffer answer while i was writing. cross post. same thing.On Friday, 19 June 2015 at 13:26:03 UTC, Steven Schveighoffer wrote:in the declaration set the return type to 'auto'. Use 'tuple' instead of 'Tuple'.[...]Thank you :) Here is th corrected version : Hi, I have a struct with some methods int it, let's say ``` struct Example{ int a(){ return someValue; } float b(){ return someOtherValue; } string stringValue(){ return c; } } Is there any way to have a asTuple method in this struct that would returns something like : Tuple!(int, "a", float, "b", string, "c") and that will contain the values of the methods of the struct ? Thanks.
Jun 19 2015
On Fri, 19 Jun 2015 13:27:13 +0000, Quentin Ladeveze wrote:Is there any way to have a asTuple method in this struct that would returns something like : Tuple!(int, "a", float, "b", string, "c") and that will contain the values of the methods of the struct ? Thanks.You'll want to work your way through this example carefully as it's basically template-based functional programming, but I think does what you want: http://dpaste.dzfl.pl/b048ea3adb93
Jun 19 2015
On Friday, 19 June 2015 at 15:36:54 UTC, Justin Whear wrote:On Fri, 19 Jun 2015 13:27:13 +0000, Quentin Ladeveze wrote:This is interesting, thank you very much ! I will try to figure out how it works nowIs there any way to have a asTuple method in this struct that would returns something like : Tuple!(int, "a", float, "b", string, "c") and that will contain the values of the methods of the struct ? Thanks.You'll want to work your way through this example carefully as it's basically template-based functional programming, but I think does what you want: http://dpaste.dzfl.pl/b048ea3adb93
Jun 19 2015