constants, enums, signed vs unsigned

[maxw]

Hello,

I didn't find crystal-clear confirmation in the documentation, but it
looks like enum values are considered _signed_ 32-bit integers. When
I try to assign 4294967295 to an enum value in a .proto file, protoc
complains. Is there any way to have unsigned 32-bit integer
constants?

I did find on this forum a suggestion ("Issue 60"), which basically
declares a "Constants" message, with fields that have default values -
those default values can then be retrieved. This does work, and also
has the benefit of allowing more types of constants (than just 32-bit
integers).

The dilemma that I'm facing is what should be the guideline to choose
between enum and this default value trick? Would it be considered
"bad form" to mix both styles?

Thank you!

[Kenton Varda]

Enums are signed, yes.

I would suggest not defining constants in .proto files at all.  There isn't really any good way of doing it.  Enums really aren't designed to be used as numeric constants (especially in Java where they aren't even numeric), but default values are also a pretty awkward way to do it.

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[Ben Wright]

Seems an odd use case to capture a constant in a proto file... but my
suggestion would be to extend FileOptions or MessageOptions and
provide options that hold your constant values.