www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.learn - Simplifying a string mixin

reply Victor Porton <porton narod.ru> writes:
Can string mixing be split into several parts?

I have a mixin like this:

     mixin("struct " ~ name ~ " {\n" ~
           "  struct Regular {\n" ~
           "    // ..." ~
           "  }\n" ~
           "  struct WithDefaults {\n" ~
           "    // ..." ~
           "  }\n" ~
           '}');

I would like to split it into several mixins (preferably using 
regular non-string mixins).

Are things like this possible?

Also, what is the most proper thing to check that `name` is a
Feb 25 2019
next sibling parent reply Adam D. Ruppe <destructionator gmail.com> writes:
On Monday, 25 February 2019 at 20:57:37 UTC, Victor Porton wrote:

 Can string mixing be split into several parts?

 I have a mixin like this:

     mixin("struct " ~ name ~ " {\n" ~
           "  struct Regular {\n" ~
           "    // ..." ~
           "  }\n" ~
           "  struct WithDefaults {\n" ~
           "    // ..." ~
           "  }\n" ~
           '}');


I'd probably write that as:

mixin(q{
   struct } ~ name ~ q{ {
     struct Regular {
        // stuff
     }
     struct With Defaults {
        // ...
     }
   }
});


 Also, what is the most proper thing to check that `name` is a 



just let the compiler do it imo.
Feb 25 2019
next sibling parent Simen =?UTF-8?B?S2rDpnLDpXM=?= <simen.kjaras gmail.com> writes:
On Monday, 25 February 2019 at 21:04:48 UTC, Adam D. Ruppe wrote:

 On Monday, 25 February 2019 at 20:57:37 UTC, Victor Porton 
 wrote:

 Also, what is the most proper thing to check that `name` is a 



 just let the compiler do it imo.


Agreed. There are times when error message can be significantly 
more readable though, if testing for valid names is done in 
intelligent places. In this case, something like this can be of 
use:

enum isValidName(string s) = __traits(compiles, { mixin("int 
"~s~";"); });

unittest {
     static assert(isValidName!"a");
     static assert(isValidName!"a_B");
     static assert(!isValidName!"6a");
     static assert(!isValidName!"");
     static assert(!isValidName!"!");
}

--
   Simen
Feb 26 2019
prev sibling parent bauss <jj_1337 live.dk> writes:
On Monday, 25 February 2019 at 21:04:48 UTC, Adam D. Ruppe wrote:

 On Monday, 25 February 2019 at 20:57:37 UTC, Victor Porton 
 wrote:

 Can string mixing be split into several parts?

 I have a mixin like this:

     mixin("struct " ~ name ~ " {\n" ~
           "  struct Regular {\n" ~
           "    // ..." ~
           "  }\n" ~
           "  struct WithDefaults {\n" ~
           "    // ..." ~
           "  }\n" ~
           '}');


 I'd probably write that as:

 mixin(q{
   struct } ~ name ~ q{ {
     struct Regular {
        // stuff
     }
     struct With Defaults {
        // ...
     }
   }
 });


 Also, what is the most proper thing to check that `name` is a 



 just let the compiler do it imo.


Or you could do:

mixin(format(q{
   struct %s {
     struct Regular {
        // stuff
     }
     struct With Defaults {
        // ...
     }
   }
}, name));

That way it's way more readable.
Feb 26 2019
prev sibling parent Jacob Carlborg <doob me.com> writes:
On 2019-02-25 21:57, Victor Porton wrote:

 Can string mixing be split into several parts?
 
 I have a mixin like this:
 
      mixin("struct " ~ name ~ " {\n" ~
            "  struct Regular {\n" ~
            "    // ..." ~
            "  }\n" ~
            "  struct WithDefaults {\n" ~
            "    // ..." ~
            "  }\n" ~
            '}');
 
 I would like to split it into several mixins (preferably using regular 
 non-string mixins).
 
 Are things like this possible?


You can create multiple functions that returns a portion of the string 
to mixin. For example:

mixin(generateCode(name));

string generateCode(string name)
{
     return part1(name) ~ part2() ~ part3(); // and so on
}


 Also, what is the most proper thing to check that `name` is a proper 



Have one of the above functions to do the validation.

-- 
/Jacob Carlborg
Feb 26 2019