digitalmars.D.learn - How do I check if this field is of this template struct?

Jack (32/32) Mar 19 2021 give below template struct, how can I list the members x, y and

Panke (12/17) Mar 19 2021 Template parameter cannot only be types but also values,

Jack (3/21) Mar 19 2021 that design is a bit different but may be worth, gonna get used

Paul Backus (3/8) Mar 19 2021 You want std.traits.isInstanceOf:

Jack (34/43) Mar 19 2021 thanks this works fine outside a method but not in a static

frame (2/6) Mar 19 2021

Jack (3/9) Mar 19 2021 indeed, it shwos an example on how to use that in a static

Steven Schveighoffer (4/49) Mar 19 2021 foo in this context is the *instantiated* foo (i.e. the struct foo

Jack (4/57) Mar 19 2021 Thank you Steve, that what I was looking for. Funny thing, I

Jack <jckj33 gmail.com> writes:

give below template struct, how can I list the members x, y and 
z? I've tried something with OriginalType and TemplateOf but no 
luck... it seems if I do foo!"str1" the "str1" became "part of 
type"? give .stringof from typeof(__traits(getMember, foo, 
field)) I thought the type would be foo!string or something.

Here's the code:

template foo(string s = null)
{
	 nogc
	struct foo
	{
		int n;

		enum x = foo!"str1"(10);
		enum y = foo!"str2"(20);
		enum z = foo!"str3"(30);

		enum myEnum { none }

		void someMethod() { }
	}
}

not working listener:

void list()
{
	static foreach(field; __traits(allMembers, foo!()))
	{{
		alias m = __traits(getMember, foo!(), field);
		static if(!isType!m && __traits(isSame, 
OriginalType!(typeof(m)), foo))
		{
			writefln("field = [%s]", field);
		}
	}}
}

Mar 19 2021

Panke <tobias pankrath.net> writes:

On Friday, 19 March 2021 at 07:14:46 UTC, Jack wrote:
 give below template struct, how can I list the members x, y and 
 z? I've tried something with OriginalType and TemplateOf but no 
 luck... it seems if I do foo!"str1" the "str1" became "part of 
 type"? give .stringof from typeof(__traits(getMember, foo, 
 field)) I thought the type would be foo!string or something.

Template parameter cannot only be types but also values, 
including strings. If you instantiate a template with different 
values you get different types.

--
struct foo(T) { }
struct bar(string s) {}

alias a = foo!string; // type of a is foo!string
alias b = bar!"str1"; // type of b is bar!"str1"
alias c = bar!"str2"; // typo of c is bar!"str2"
static assert (!is(typeof(c) == typeof(b)));
--

Mar 19 2021

Jack <jckj33 gmail.com> writes:

On Friday, 19 March 2021 at 07:56:26 UTC, Panke wrote:
 On Friday, 19 March 2021 at 07:14:46 UTC, Jack wrote:
 give below template struct, how can I list the members x, y 
 and z? I've tried something with OriginalType and TemplateOf 
 but no luck... it seems if I do foo!"str1" the "str1" became 
 "part of type"? give .stringof from typeof(__traits(getMember, 
 foo, field)) I thought the type would be foo!string or 
 something.

 Template parameter cannot only be types but also values, 
 including strings. If you instantiate a template with different 
 values you get different types.

that design is a bit different but may be worth, gonna get used 
to it

 --
 struct foo(T) { }
 struct bar(string s) {}

 alias a = foo!string; // type of a is foo!string
 alias b = bar!"str1"; // type of b is bar!"str1"
 alias c = bar!"str2"; // typo of c is bar!"str2"
 static assert (!is(typeof(c) == typeof(b)));
 --

Mar 19 2021

Paul Backus <snarwin gmail.com> writes:

On Friday, 19 March 2021 at 07:14:46 UTC, Jack wrote:
 give below template struct, how can I list the members x, y and 
 z? I've tried something with OriginalType and TemplateOf but no 
 luck... it seems if I do foo!"str1" the "str1" became "part of 
 type"? give .stringof from typeof(__traits(getMember, foo, 
 field)) I thought the type would be foo!string or something.

You want std.traits.isInstanceOf:

     static if(!isType!m && isInstanceOf!(foo, typeof(m)))

Mar 19 2021

Jack <jckj33 gmail.com> writes:

On Friday, 19 March 2021 at 08:54:50 UTC, Paul Backus wrote:
 On Friday, 19 March 2021 at 07:14:46 UTC, Jack wrote:
 give below template struct, how can I list the members x, y 
 and z? I've tried something with OriginalType and TemplateOf 
 but no luck... it seems if I do foo!"str1" the "str1" became 
 "part of type"? give .stringof from typeof(__traits(getMember, 
 foo, field)) I thought the type would be foo!string or 
 something.

 You want std.traits.isInstanceOf:

     static if(!isType!m && isInstanceOf!(foo, typeof(m)))

thanks this works fine outside a method but not in a static 
method. what am I missing?

void main()
{
         // doesn't print anything
	Foo.list();
}

alias Foo = foo!();

template foo(string s = null)
{
	 nogc
	struct foo
	{
		int n;

		enum x = foo!"str1"(10);
		enum y = foo!"str2"(20);
		enum z = foo!"str3"(30);

		enum myEnum { none }

		void someMethod() { }

		static void list()
		{
			//writeln("members = ", [__traits(allMembers, foo!())]);
			static foreach(field; __traits(allMembers, foo!()))
			{{
				alias m = __traits(getMember, foo!(), field);
				static if(!isType!m && isInstanceOf!(foo, typeof(m)))
				{
					writefln("field = [%s]", field);
				}
			}}
		}
	}
}

Mar 19 2021

frame <frame86 live.com> writes:

On Friday, 19 March 2021 at 16:41:11 UTC, Jack wrote:

 thanks this works fine outside a method but not in a static 
 method. what am I missing?

Reading the manual ;)

 To use isInstanceOf to check the identity of a template while 
 inside of said template, use TemplateOf.

Mar 19 2021

Jack <jckj33 gmail.com> writes:

On Friday, 19 March 2021 at 17:40:39 UTC, frame wrote:
 On Friday, 19 March 2021 at 16:41:11 UTC, Jack wrote:

 thanks this works fine outside a method but not in a static 
 method. what am I missing?

 Reading the manual ;)

 To use isInstanceOf to check the identity of a template while 
 inside of said template, use TemplateOf.


indeed, it shwos an example on how to use that in a static 
function

Mar 19 2021

Steven Schveighoffer <schveiguy gmail.com> writes:

On 3/19/21 12:41 PM, Jack wrote:
 On Friday, 19 March 2021 at 08:54:50 UTC, Paul Backus wrote:
 On Friday, 19 March 2021 at 07:14:46 UTC, Jack wrote:
 give below template struct, how can I list the members x, y and z? 
 I've tried something with OriginalType and TemplateOf but no luck... 
 it seems if I do foo!"str1" the "str1" became "part of type"? give 
 .stringof from typeof(__traits(getMember, foo, field)) I thought the 
 type would be foo!string or something.

 You want std.traits.isInstanceOf:

     static if(!isType!m && isInstanceOf!(foo, typeof(m)))

 
 thanks this works fine outside a method but not in a static method. what 
 am I missing?
 
 void main()
 {
          // doesn't print anything
      Foo.list();
 }
 
 alias Foo = foo!();
 
 template foo(string s = null)
 {
       nogc
      struct foo
      {
          int n;
 
          enum x = foo!"str1"(10);
          enum y = foo!"str2"(20);
          enum z = foo!"str3"(30);
 
          enum myEnum { none }
 
          void someMethod() { }
 
          static void list()
          {
              //writeln("members = ", [__traits(allMembers,
foo!())]);
              static foreach(field; __traits(allMembers, foo!()))
              {{
                  alias m = __traits(getMember, foo!(), field);
                  static if(!isType!m && isInstanceOf!(foo,
typeof(m)))

foo in this context is the *instantiated* foo (i.e. the struct foo 
above). What you want is `isIsntanceOf!(.foo, typeof(m))`

-Steve

Mar 19 2021

Jack <jckj33 gmail.com> writes:

On Saturday, 20 March 2021 at 00:16:06 UTC, Steven Schveighoffer 
wrote:
 On 3/19/21 12:41 PM, Jack wrote:
 On Friday, 19 March 2021 at 08:54:50 UTC, Paul Backus wrote:
 On Friday, 19 March 2021 at 07:14:46 UTC, Jack wrote:
 give below template struct, how can I list the members x, y 
 and z? I've tried something with OriginalType and TemplateOf 
 but no luck... it seems if I do foo!"str1" the "str1" became 
 "part of type"? give .stringof from 
 typeof(__traits(getMember, foo, field)) I thought the type 
 would be foo!string or something.

 You want std.traits.isInstanceOf:

     static if(!isType!m && isInstanceOf!(foo, typeof(m)))

 
 thanks this works fine outside a method but not in a static 
 method. what am I missing?
 
 void main()
 {
          // doesn't print anything
      Foo.list();
 }
 
 alias Foo = foo!();
 
 template foo(string s = null)
 {
       nogc
      struct foo
      {
          int n;
 
          enum x = foo!"str1"(10);
          enum y = foo!"str2"(20);
          enum z = foo!"str3"(30);
 
          enum myEnum { none }
 
          void someMethod() { }
 
          static void list()
          {
              //writeln("members = ", [__traits(allMembers, 
 foo!())]);
              static foreach(field; __traits(allMembers, 
 foo!()))
              {{
                  alias m = __traits(getMember, foo!(), field);
                  static if(!isType!m && isInstanceOf!(foo, 
 typeof(m)))

 foo in this context is the *instantiated* foo (i.e. the struct 
 foo above). What you want is `isIsntanceOf!(.foo, typeof(m))`

 -Steve

Thank you Steve, that what I was looking for. Funny thing, I 
totally forget about the . operator

Mar 19 2021

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digitalmars.D.learn - How do I check if this field is of this template struct?