Hi.
I want to somehow list members of a class in the order of their
declaration. The immediate goal is to generate a few functions,
like the "default" constructor for structs but only with all the
fields, or the "reader" function, but I'm interested in the
general question as well.
I can go the hard way and wrap every declaration into something
that will collect them and then list in the right order. The
problem is, the declarations won't look normal then.
The documentation for __traits (allMembers, ...), __traits
(derivedMembers, ...) and the like [1] explicitly says that the
order is not defined. Still, I've looked at Atila Neves'
Cerealed serializer library, and it does use them [2]. Does it
mean the order is unlikely to change at this point?
The documentation for std.traits' RepresentationTypeTuple [3]
says things are listed in topological order, which formally does
not restrict the order for flat structures again. And the
underlying implementation [4] of Fields uses .tupleof class
property which, in turn, does not list any guarantees on the
order [5].
So I'm confused. What is considered the right way to list
members when I care about their linear order?
Ivan Kazmenko.
[1] https://dlang.org/spec/traits.html#derivedMembers
[2]
https://github.com/atilaneves/cerealed/blob/master/src/cerealed/cereal.d#L467
[3]
https://dlang.org/phobos/std_traits.html#RepresentationTypeTuple
[4]
https://github.com/dlang/phobos/blob/10cd84a/std/traits.d#L2279
[5] https://dlang.org/spec/class.html#class_properties
