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

"Quentin Ladeveze" <ladeveze.quentin openmailbox.org> writes:

Hi,

   I have a struct with some methods int it, let's say

```
struct Example{
    int intValue(){

Jun 19 2015

"Quentin Ladeveze" <ladeveze.quentin openmailbox.org> writes:

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

Steven Schveighoffer <schveiguy yahoo.com> writes:

On 6/19/15 9:13 AM, Quentin Ladeveze wrote:
 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 ?

You can't. The forum is backed by a newsgroup, just post the full 
corrected version :)

-Steve

Jun 19 2015

"Quentin Ladeveze" <ladeveze.quentin openmailbox.org> writes:

On Friday, 19 June 2015 at 13:26:03 UTC, Steven Schveighoffer 
wrote:
 On 6/19/15 9:13 AM, Quentin Ladeveze wrote:
 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 ?

 You can't. The forum is backed by a newsgroup, just post the 
 full corrected version :)

 -Steve

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

Steven Schveighoffer <schveiguy yahoo.com> writes:

On 6/19/15 9:27 AM, Quentin Ladeveze wrote:
 On Friday, 19 June 2015 at 13:26:03 UTC, Steven Schveighoffer wrote:
 On 6/19/15 9:13 AM, Quentin Ladeveze wrote:
 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 ?

 You can't. The forum is backed by a newsgroup, just post the full
 corrected version :)

 -Steve

 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 ?

Does this work for you, or is there a further expectation?

auto asTuple() { return Tuple!(int, "a", ...)(a, b, stringValue);}

-Steve

Jun 19 2015

"Quentin Ladeveze" <ladeveze.quentin openmailbox.org> writes:

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);}

 -Steve

In 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

"Baz" <bb.temp gmx.com> writes:

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:
 Does this work for you, or is there a further expectation?

 auto asTuple() { return Tuple!(int, "a", ...)(a, b, 
 stringValue);}

 -Steve

 In 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.

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=2

Jun 19 2015

Steven Schveighoffer <schveiguy yahoo.com> writes:

On 6/19/15 10:01 AM, Baz wrote:
 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:
 Does this work for you, or is there a further expectation?

 auto asTuple() { return Tuple!(int, "a", ...)(a, b, stringValue);}

 -Steve

 In 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.

 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=2

Actually, this isn't a voldemort type, because the type can be named 
outside the function.

-Steve

Jun 19 2015

Daniel =?UTF-8?B?S296w6Fr?= via Digitalmars-d-learn writes:

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:
 Does this work for you, or is there a further expectation?

 auto asTuple() { return Tuple!(int, "a", ...)(a, b, 
 stringValue);}

 -Steve

 
 In 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.

http://dlang.org/phobos/std_traits.html#ReturnType
http://dlang.org/phobos/std_traits.html#ParameterTypeTuple

Jun 19 2015

"Quentin Ladeveze" <ladeveze.quentin openmailbox.org> writes:

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:

 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);}

 -Steve

 
 In 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.

 http://dlang.org/phobos/std_traits.html#ReturnType 
 http://dlang.org/phobos/std_traits.html#ParameterTypeTuple

These are interesting and can be useful, but allMembers returns 
strings and not functions, so I can't apply ReturnType.

Jun 19 2015

Steven Schveighoffer <schveiguy yahoo.com> writes:

On 6/19/15 10:13 AM, Quentin Ladeveze wrote:
 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:

 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);}

 -Steve

 In 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.

 http://dlang.org/phobos/std_traits.html#ReturnType
 http://dlang.org/phobos/std_traits.html#ParameterTypeTuple

 These are interesting and can be useful, but allMembers returns strings
 and not functions, so I can't apply ReturnType.

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.

-Steve

Jun 19 2015

"Quentin Ladeveze" <ladeveze.quentin openmailbox.org> writes:

On Friday, 19 June 2015 at 14:42:59 UTC, Steven Schveighoffer 
wrote:
 On 6/19/15 10:13 AM, Quentin Ladeveze wrote:
 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:

 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);}

 -Steve

 In 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.

 http://dlang.org/phobos/std_traits.html#ReturnType
 http://dlang.org/phobos/std_traits.html#ParameterTypeTuple

 These are interesting and can be useful, but allMembers 
 returns strings
 and not functions, so I can't apply ReturnType.

 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.

 -Steve

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 ?

Jun 19 2015

Steven Schveighoffer <schveiguy yahoo.com> writes:

On 6/19/15 12:09 PM, Quentin Ladeveze wrote:
 On Friday, 19 June 2015 at 14:42:59 UTC, Steven Schveighoffer wrote:
 On 6/19/15 10:13 AM, Quentin Ladeveze wrote:
 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:

 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);}
 -Steve

 In 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.

 http://dlang.org/phobos/std_traits.html#ReturnType
 http://dlang.org/phobos/std_traits.html#ParameterTypeTuple

 These are interesting and can be useful, but allMembers returns strings
 and not functions, so I can't apply ReturnType.

 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.

 -Steve

 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 ?

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!

-Steve

Jun 19 2015

"ZombineDev" <valid_email he.re> writes:

On Friday, 19 June 2015 at 14:13:46 UTC, Quentin Ladeveze wrote:
 [..]

 These are interesting and can be useful, but allMembers returns 
 strings and not functions, so I can't apply ReturnType.

Here's my solution:
http://dpaste.dzfl.pl/c69de3c16d75

Jun 19 2015

"Quentin Ladeveze" <ladeveze.quentin openmailbox.org> writes:

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:
 [..]

 These are interesting and can be useful, but allMembers 
 returns strings and not functions, so I can't apply ReturnType.

 Here's my solution:
 http://dpaste.dzfl.pl/c69de3c16d75

Thank you very much, this solution is interesting too.

Jun 19 2015

"Baz" <bb.temp gmx.com> writes:

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:
 On 6/19/15 9:13 AM, Quentin Ladeveze wrote:
 [...]

 You can't. The forum is backed by a newsgroup, just post the 
 full corrected version :)

 -Steve

 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.

in the declaration set the return type to 'auto'.
Use 'tuple' instead of 'Tuple'.

Jun 19 2015

"Baz" <bb.temp gmx.com> writes:

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:
 On Friday, 19 June 2015 at 13:26:03 UTC, Steven Schveighoffer 
 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.

 in the declaration set the return type to 'auto'.
 Use 'tuple' instead of 'Tuple'.

Ah, damn, haven't see Steven Schveighoffer answer while i was 
writing. cross post. same thing.

Jun 19 2015

Justin Whear <justin economicmodeling.com> writes:

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

"Quentin Ladeveze" <ladeveze.quentin openmailbox.org> writes:

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:
 
 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

This is interesting, thank you very much ! I will try to figure 
out how it works now

Jun 19 2015

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digitalmars.D.learn - Return types of the methods of a struct