digitalmars.D - Identifier hierarchy

=?UTF-8?B?THXDrXM=?= Marques (10/10) Jun 11 2018 Just to check. If you have a piece of code like "foo.bar.baz",

Mike Franklin (4/7) Jun 11 2018 Are you looking for this:

Simen =?UTF-8?B?S2rDpnLDpXM=?= (18/27) Jun 11 2018 That only works for modules and types - Luís mentioned that

Basile B. (16/45) Jun 11 2018 the FQN is working here but i find the first message a bit

=?UTF-8?B?THXDrXM=?= Marques (16/30) Jun 11 2018 That gets the types foo, bar, baz. I wanted the identifiers.

Basile B. (18/55) Jun 11 2018 thanks that's clear now... it's indeed not possible
Stefan Koch (37/74) Jun 11 2018 this can only work unambiguously if Son is defined nested inside

=?UTF-8?B?THXDrXM=?= Marques (3/5) Jun 11 2018 Thanks for your solution. Unfortunately, it really doesn't cover

=?UTF-8?B?THXDrXM=?= Marques <luis luismarques.eu> writes:

Just to check. If you have a piece of code like "foo.bar.baz", 
you can get the full hierarchy, for instance with stringof:


      static assert(foo.bar.baz.stringof == "foo.bar.bar");

But once you pass foo.bar.baz to a template, there's no way to 
recover the full path, is there? You only get baz. You can ask 
for the __traits(parent, baz), but you only get the type of bar, 
not the identifier.

Assuming you pass the foo.bar.baz normally (alias arg) to the 
template (not as a string, for instance), there's no workaround 
for this, is there?

Jun 11 2018

Mike Franklin <slavo5150 yahoo.com> writes:

On Monday, 11 June 2018 at 12:38:33 UTC, Luís Marques wrote:
 Just to check. If you have a piece of code like "foo.bar.baz", 
 you can get the full hierarchy, for instance with stringof:


      static assert(foo.bar.baz.stringof == "foo.bar.bar");

Are you looking for this: 
https://dlang.org/phobos/std_traits.html#fullyQualifiedName ?

Mike

Jun 11 2018

Simen =?UTF-8?B?S2rDpnLDpXM=?= <simen.kjaras gmail.com> writes:

On Monday, 11 June 2018 at 12:59:01 UTC, Mike Franklin wrote:
 On Monday, 11 June 2018 at 12:38:33 UTC, Luís Marques wrote:
 Just to check. If you have a piece of code like "foo.bar.baz", 
 you can get the full hierarchy, for instance with stringof:


      static assert(foo.bar.baz.stringof == "foo.bar.bar");

 Are you looking for this: 
 https://dlang.org/phobos/std_traits.html#fullyQualifiedName ?

That only works for modules and types - Luís mentioned that 
__traits(identifier) only returns the type, not the identifier. 
Consider:

module foo;
import std.traits;

struct S { int n; }

unittest {
     S s;
     // Prints "s.n"
     pragma(msg, s.n.stringof);
     // Prints "foo.S.n".
     pragma(msg, fullyQualifiedName!(s.n));
}

As for getting the name s.n inside a template, I don't think 
that's currently possible.

--
   Simen

Jun 11 2018

Basile B. <b2.b2.b2.temp.temp gmx.com> writes:

On Monday, 11 June 2018 at 13:19:17 UTC, Simen Kjærås wrote:
 On Monday, 11 June 2018 at 12:59:01 UTC, Mike Franklin wrote:
 On Monday, 11 June 2018 at 12:38:33 UTC, Luís Marques wrote:
 Just to check. If you have a piece of code like 
 "foo.bar.baz", you can get the full hierarchy, for instance 
 with stringof:


      static assert(foo.bar.baz.stringof == "foo.bar.bar");

 Are you looking for this: 
 https://dlang.org/phobos/std_traits.html#fullyQualifiedName ?

 That only works for modules and types - Luís mentioned that 
 __traits(identifier) only returns the type, not the identifier. 
 Consider:

 module foo;
 import std.traits;

 struct S { int n; }

 unittest {
     S s;
     // Prints "s.n"
     pragma(msg, s.n.stringof);
     // Prints "foo.S.n".
     pragma(msg, fullyQualifiedName!(s.n));
 }

 As for getting the name s.n inside a template, I don't think 
 that's currently possible.

 --
   Simen

the FQN is working here but i find the first message a bit 
confuse. Not sure if this small runnable represents the issue ?


---
module runnable;

import std.stdio, std.traits;

struct foo {  struct bar { static int baz;} }

template Test(alias arg)
{
     pragma(msg, fullyQualifiedName!arg);
}

void main()
{
     alias t = Test!(foo.bar.baz); // runnable.foo.bar.baz
}
---

Jun 11 2018

=?UTF-8?B?THXDrXM=?= Marques <luis luismarques.eu> writes:

On Monday, 11 June 2018 at 13:39:22 UTC, Basile B. wrote:
 the FQN is working here but i find the first message a bit 
 confuse. Not sure if this small runnable represents the issue ?


 ---
 module runnable;

 import std.stdio, std.traits;

 struct foo {  struct bar { static int baz;} }

 template Test(alias arg)
 {
     pragma(msg, fullyQualifiedName!arg);
 }

 void main()
 {
     alias t = Test!(foo.bar.baz); // runnable.foo.bar.baz
 }

That gets the types foo, bar, baz. I wanted the identifiers. 
Something like this:

struct Parent
{
     Son son;
}

struct Son
{
     int value;
}

void main()
{
     Parent parent;
     alias t = Magic!(parent.son); // t is now parent (not Parent)
}

Jun 11 2018

Basile B. <b2.b2.b2.temp.temp gmx.com> writes:

On Monday, 11 June 2018 at 13:47:41 UTC, Luís Marques wrote:
 On Monday, 11 June 2018 at 13:39:22 UTC, Basile B. wrote:
 the FQN is working here but i find the first message a bit 
 confuse. Not sure if this small runnable represents the issue ?


 ---
 module runnable;

 import std.stdio, std.traits;

 struct foo {  struct bar { static int baz;} }

 template Test(alias arg)
 {
     pragma(msg, fullyQualifiedName!arg);
 }

 void main()
 {
     alias t = Test!(foo.bar.baz); // runnable.foo.bar.baz
 }

 That gets the types foo, bar, baz. I wanted the identifiers. 
 Something like this:

 struct Parent
 {
     Son son;
 }

 struct Son
 {
     int value;
 }

 void main()
 {
     Parent parent;
     alias t = Magic!(parent.son); // t is now parent (not 
 Parent)
 }

thanks that's clear now... it's indeed not possible

---
module runnable;

import std.stdio, std.traits;

struct Foo {struct Bar{static int baz;} Bar bar;}
Foo foo;

template Test(alias arg)
{
     // challenge: get "foo.bar.baz" here...
}

void main()
{
     alias t = Test!(foo.bar.baz);
}
---

Maybe something with opDispatch but it sounds complicated at 
first glance.

Jun 11 2018

Stefan Koch <uplink.coder googlemail.com> writes:

On Monday, 11 June 2018 at 13:47:41 UTC, Luís Marques wrote:
 On Monday, 11 June 2018 at 13:39:22 UTC, Basile B. wrote:
 the FQN is working here but i find the first message a bit 
 confuse. Not sure if this small runnable represents the issue ?


 ---
 module runnable;

 import std.stdio, std.traits;

 struct foo {  struct bar { static int baz;} }

 template Test(alias arg)
 {
     pragma(msg, fullyQualifiedName!arg);
 }

 void main()
 {
     alias t = Test!(foo.bar.baz); // runnable.foo.bar.baz
 }

 That gets the types foo, bar, baz. I wanted the identifiers. 
 Something like this:

 struct Parent
 {
     Son son;
 }

 struct Son
 {
     int value;
 }

 void main()
 {
     Parent parent;
     alias t = Magic!(parent.son); // t is now parent (not 
 Parent)
 }

this can only work unambiguously if Son is defined nested inside 
Parent.
Otherwise it's lexical parent will be the module.
So let's assume we have this structure

struct Parent
{
    double d;
    struct Son { int value; }
    Son son;
}

void main()
{
     Parent p;
     p.d = 3.141;
     auto pfs = Magic(p.son);
     static assert(is(typeof(pfs) == Parent*));
     assert(&pfs.son == &p.son);
     assert(pfs.d == 3.141);
}

auto Magic(S)(ref S s)
{
     alias P = typeof(__traits(parent, S).init);
     enum s_index =
     () {
         foreach(i,m;[__traits(allMembers, P)])
         {
             if (__traits(identifier, S) == m)
             {
                 return i;
             }
         }
         assert(0);
     } ();
     enum s_offset = P.init.tupleof[s_index].offsetof;
     return cast(P*)( (cast(void*)&s) - s_offset);
}

Jun 11 2018

=?UTF-8?B?THXDrXM=?= Marques <luis luismarques.eu> writes:

On Monday, 11 June 2018 at 20:49:01 UTC, Stefan Koch wrote:
 this can only work unambiguously if Son is defined nested 
 inside Parent.

Thanks for your solution. Unfortunately, it really doesn't cover 
my use case.

Jun 11 2018

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