digitalmars.D - Generating enum members
- Milli (23/23) Mar 15 Hello everyone.
- H. S. Teoh (18/40) Mar 15 [...]
- Milli (4/5) Mar 15 CTFE simplifies greatly how i can approach my problem, thank you
- cc (25/48) Mar 27 If you have a 1:1 relationship between the enums, you could also
Hello everyone.
It's my first time starting a thread here please have patience
and let me know if there is anything i have done wrong!
I'm currently doing a project where there are two pretty lengthy
enums whose members depend on each other.
Declaring one after the other makes it hard to double check that
i haven't missed anything, which is why i'm trying to make a
template mixin where i can declare the members together and the
template does all the appropriate sorting.
I'm not having any luck in generating the enums though.
The simplified version of what i need would be
```D
mixin template create_enum(alias members) {
enum enumname {
static foreach(member; members) {
mixin(member.stringof,",");
}
}
}
```
which obviously doesn't work.
Is it possible at all to do something like this in D?
Thank you for the help!
Mar 15
On Sat, Mar 15, 2025 at 02:47:01PM +0000, Milli via Digitalmars-d wrote:
[...]
I'm currently doing a project where there are two pretty lengthy enums
whose members depend on each other.
Declaring one after the other makes it hard to double check that i
haven't missed anything, which is why i'm trying to make a template
mixin where i can declare the members together and the template does
all the appropriate sorting.
I'm not having any luck in generating the enums though.
The simplified version of what i need would be
```D
mixin template create_enum(alias members) {
enum enumname {
static foreach(member; members) {
mixin(member.stringof,",");
}
}
}
```
which obviously doesn't work.
Is it possible at all to do something like this in D?
[...]
Of course it's possible. D is the king of meta-programming, and
something like this is right up its alley.
What you want is a string mixin + CTFE:
string create_enum(string[] members) {
string code = "enum MyEnum { ";
foreach (memb; members) {
code ~= memb ~ ", ";
}
code ~= "}";
return code;
}
mixin(create_enum([ "memb1", "memb2", "memb3" ]);
T
--
Knowledge is that area of ignorance that we arrange and classify. -- Ambrose
Bierce
Mar 15
Milli <alezardo02 gmail.com> On Saturday, 15 March 2025 at 15:08:06 UTC, H. S. Teoh wrote: oh my i don't know how i missed this feature of D altogether!What you want is a string mixin + CTFE:CTFE simplifies greatly how i can approach my problem, thank you a lot!
Mar 15
On Saturday, 15 March 2025 at 14:47:01 UTC, Milli wrote:
Hello everyone.
It's my first time starting a thread here please have patience
and let me know if there is anything i have done wrong!
I'm currently doing a project where there are two pretty
lengthy enums whose members depend on each other.
Declaring one after the other makes it hard to double check
that i haven't missed anything, which is why i'm trying to make
a template mixin where i can declare the members together and
the template does all the appropriate sorting.
I'm not having any luck in generating the enums though.
The simplified version of what i need would be
```D
mixin template create_enum(alias members) {
enum enumname {
static foreach(member; members) {
mixin(member.stringof,",");
}
}
}
```
which obviously doesn't work.
Is it possible at all to do something like this in D?
Thank you for the help!
If you have a 1:1 relationship between the enums, you could also
declare one first as normal and then use templates/mixins to
generate the second based on the first:
```d
enum FooA {
RED = 1,
GREEN = 2,
BLUE = 4,
}
mixin(cloneEnum!(FooA, "FooB"));
string cloneEnum(E, string name)() {
string s = "enum "~name~" {";
foreach (member; EnumMembers!E) {
s ~= format("%s = %s.%s,", member, E.stringof, member);
}
s ~= "}";
return s;
}
void main() {
assert(cast(int) FooA.BLUE == cast(int) FooB.BLUE);
}
```
And of course you can modify the function if you need any special
logic to exclude or modify some members.
Mar 27