Hi,
I've been looking at the reflection api for a way to inspect the layout of 
the encoded data. Specifically what I've been looking for is a reliable way 
to find the word-offset of the beginning of a given struct. Is there a way 
to do that?

For context, the reason I need it is that I need to keep some proto-encoded 
data up to date with small changes that come in occasionally. So I need a 
mechanism for representing just the deltas between two versions of a proto, 
and ideally a really simple way that works just on the binary encoded data. 
The data is mainly flat lists of structs. A simple approach I wanted to try 
was to simply xor the entire before- and after- binaries and then zipping 
the result. Before and after will be very similar so the xor should be 
mostly 0 and so zipping should shrink it down to hardly anything. Except 
there's a hitch: if just one of the structs changes size the other elements 
will shift around and not line up, and xor'ing won't cancel them out. But 
if I could determine where in the binary each element starts I can line 
corresponding elements up by 0-padding (which would be removed again when 
applying the update) and then the scheme should work.


c

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