Hi,
I wonder if it will be possible to add support for "scoped" enum to GCC.
The current C standard has one name space for all enums, and different name
space for the members of each "struct". As a result, possible to say
struct foo { int a } ;
struct bar { double a }; // This is different 'a', different type
But illegal to to (ignoring the conversion to use all upper for enum).
enum a { u, v } ;
enum b { v, w } ; // can not do this, as 'v' must be distinct
One annoying side effect is that any package/module creating an enum has to
worry about namespace collision with everyone else in the world. Common
practices include distinct prefixes, similar to the way different libraries
use distinct prefixes to avoid function name collision. This solution is
far from perfect and leads to excessive long enum name.
A reasonable wish list - add a magic keyword that will place the enums into
a scope, so that the following work:
SCOPED enum shirt_sz { small, medium, large } ;
SCOPED enum shoe_sz { small, medium, medium_wide, large, xlarge } ;
enum shirt_sz tshift_size = shift_sz.medium ;
enum shoe_siz boot_size = shoe_sz.xlarge ;
Not perfect, but not complex, will make enum reusable across many scenario,
where they are currently hard to implement - because of namespace conflict
- between system header and user headers, between different packages.
A smart compiler can also alert when "types" are mixed (assign value from
shift_sz to a variable of type shoe_sz). Not critical - as my understanding
is that this is not enforced today. For the case that an enum symbol is
distinct (in the current compilation unit), the compiler can allow using it
without the namespace - practically falling back into current behavior.
Feedback ? Anyone know how to get a prototype into gcc ? How one get
approval for such "extensions".
Yair
