www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.learn - version specific enum members

reply "Phil Deets" <pjdeets2 gmail.com> writes:
Hi, is there a way to add members to an enum based on conditional  
compilation symbols. I tried

enum Tag {
    A, B,
    version (symbol) {
       C, D,
    }
    E,
}

but it doesn't work. I know I could do

version (symbol) {
    enum Tag { A, B, C, D, E }
} else {
    enum Tag { A, B, E }
}

but I don't want to do that since in my case, there can be quite a few  
elements outside of the version, and I don't want to repeat them all.


-- 
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/
Oct 29 2009
next sibling parent reply Ellery Newcomer <ellery-newcomer utulsa.edu> writes:
Phil Deets wrote:

 Hi, is there a way to add members to an enum based on conditional
 compilation symbols. I tried
 
 enum Tag {
    A, B,
    version (symbol) {
       C, D,
    }
    E,
 }
 
 but it doesn't work. I know I could do
 
 version (symbol) {
    enum Tag { A, B, C, D, E }
 } else {
    enum Tag { A, B, E }
 }
 
 but I don't want to do that since in my case, there can be quite a few
 elements outside of the version, and I don't want to repeat them all.
 
 



Unfortunately, that's going to be about the best you can do, unless
you're willing to play with string mixins and their ilk.
Oct 29 2009
parent reply Ary Borenszweig <ary esperanto.org.ar> writes:
Ellery Newcomer wrote:

 Phil Deets wrote:

 Hi, is there a way to add members to an enum based on conditional
 compilation symbols. I tried

 enum Tag {
    A, B,
    version (symbol) {
       C, D,
    }
    E,
 }

 but it doesn't work. I know I could do

 version (symbol) {
    enum Tag { A, B, C, D, E }
 } else {
    enum Tag { A, B, E }
 }

 but I don't want to do that since in my case, there can be quite a few
 elements outside of the version, and I don't want to repeat them all.



 Unfortunately, that's going to be about the best you can do, unless
 you're willing to play with string mixins and their ilk.



Or unless you create an enhancement request. That seems a very valid one.
Oct 29 2009
parent Ary Borenszweig <ary esperanto.org.ar> writes:
Phil Deets wrote:

 On Thu, 29 Oct 2009 18:28:12 -0500, Ary Borenszweig 
 <ary esperanto.org.ar> wrote:
 

 Ellery Newcomer wrote:

 Phil Deets wrote:

 Hi, is there a way to add members to an enum based on conditional
 compilation symbols. I tried

 enum Tag {
    A, B,
    version (symbol) {
       C, D,
    }
    E,
 }

 but it doesn't work. I know I could do

 version (symbol) {
    enum Tag { A, B, C, D, E }
 } else {
    enum Tag { A, B, E }
 }

 but I don't want to do that since in my case, there can be quite a few
 elements outside of the version, and I don't want to repeat them all.



 you're willing to play with string mixins and their ilk.



 Or unless you create an enhancement request. That seems a very valid one.



 Done (on the main D list).



I meant a bugzilla enhancement, otherwise it'll get lost in the newsgroups.
Oct 30 2009
prev sibling next sibling parent "Phil Deets" <pjdeets2 gmail.com> writes:
On Thu, 29 Oct 2009 18:28:12 -0500, Ary Borenszweig <ary esperanto.org.ar>  
wrote:


 Ellery Newcomer wrote:

 Phil Deets wrote:

 Hi, is there a way to add members to an enum based on conditional
 compilation symbols. I tried

 enum Tag {
    A, B,
    version (symbol) {
       C, D,
    }
    E,
 }

 but it doesn't work. I know I could do

 version (symbol) {
    enum Tag { A, B, C, D, E }
 } else {
    enum Tag { A, B, E }
 }

 but I don't want to do that since in my case, there can be quite a few
 elements outside of the version, and I don't want to repeat them all.



 you're willing to play with string mixins and their ilk.



 Or unless you create an enhancement request. That seems a very valid one.



Done (on the main D list).
Oct 29 2009
prev sibling next sibling parent Daniel Keep <daniel.keep.lists gmail.com> writes:
Phil Deets wrote:

 Hi, is there a way to add members to an enum based on conditional
 compilation symbols. I tried
 
 enum Tag {
    A, B,
    version (symbol) {
       C, D,
    }
    E,
 }
 
 but it doesn't work. I know I could do
 
 version (symbol) {
    enum Tag { A, B, C, D, E }
 } else {
    enum Tag { A, B, E }
 }
 
 but I don't want to do that since in my case, there can be quite a few
 elements outside of the version, and I don't want to repeat them all.



template Version(char[] ident)
{
    mixin(`version(`~ident~`) const Version = true;
           else const Version = false;`);
}

char[] genEnum(bool flag1, bool flag2)
{
    return "A, B, "
         ~ (flag1 ? "C, D, " : "")
         ~ "E, F, "
         ~ (flag2 ? "G, H, " : "")
         ~ "G, ";
}

mixin(genEnum( Version!(`symbol`), Version!(`somethingElse`) ));

... is about the best you can do, I think.
Oct 29 2009
prev sibling next sibling parent "Phil Deets" <pjdeets2 gmail.com> writes:
On Fri, 30 Oct 2009 00:03:23 -0500, Daniel Keep  
<daniel.keep.lists gmail.com> wrote:


 Phil Deets wrote:

 Hi, is there a way to add members to an enum based on conditional
 compilation symbols. I tried

 enum Tag {
    A, B,
    version (symbol) {
       C, D,
    }
    E,
 }

 but it doesn't work. I know I could do

 version (symbol) {
    enum Tag { A, B, C, D, E }
 } else {
    enum Tag { A, B, E }
 }

 but I don't want to do that since in my case, there can be quite a few
 elements outside of the version, and I don't want to repeat them all.



 template Version(char[] ident)
 {
     mixin(`version(`~ident~`) const Version = true;
            else const Version = false;`);
 }

 char[] genEnum(bool flag1, bool flag2)
 {
     return "A, B, "
          ~ (flag1 ? "C, D, " : "")
          ~ "E, F, "
          ~ (flag2 ? "G, H, " : "")
          ~ "G, ";
 }

 mixin(genEnum( Version!(`symbol`), Version!(`somethingElse`) ));

 ... is about the best you can do, I think.



Hey, thanks for the idea. I worked with it a little bit to remove the  
generator function and use multiline strings. This is what I came up with.

mixin(q"ENUM
enum Tag
{
    A, B,
ENUM"~(Version!("symbol")?q"ENUM
    C, D,
ENUM":"")~q"ENUM
    E,
}
ENUM");

That's not pretty, but it's good enough for me.
Oct 29 2009
prev sibling parent "Phil Deets" <pjdeets2 gmail.com> writes:
On Fri, 30 Oct 2009 06:38:44 -0500, Ary Borenszweig <ary esperanto.org.ar>  
wrote:


 Phil Deets wrote:

 On Thu, 29 Oct 2009 18:28:12 -0500, Ary Borenszweig  
 <ary esperanto.org.ar> wrote:


 Ellery Newcomer wrote:

  Unfortunately, that's going to be about the best you can do, unless
 you're willing to play with string mixins and their ilk.



 Or unless you create an enhancement request. That seems a very valid  
 one.






 I meant a bugzilla enhancement, otherwise it'll get lost in the  
 newsgroups.



Well, I wanted to gauge support for the idea. It turns out I found a  
string mixin workaround that works; so it isn't critical for me now.
Oct 30 2009