expost API for testing type consistency

[tpapp]

If a user writes values of a type

struct Foo
    a::Int64
end

and then later redefines the type as

struct Foo
    a::Int64
    b::Int64
end

and reads from a jld2 file, JLD2 (and also, of course, JLD) can catch the inconsistency between the two definitions. It would be great have the API for this exposed, eg as write_type_fingerprint(jldfile, "Foo", Foo) and similarly as a read method.

[JonasIsensee]

I'm sorry, I don't quite understand what you are suggesting.

[tpapp]

A way to detect this situation before reading the data (and throwing an error).