MurmurHash : Added string constructor and fromString function.

[proberts-cinesite]

Adds the ability to reconstruct a IECore.MurmurHash from its string representation, which is useful if you want to store the hash as StringData in a primitive variable for example.

Breaking Changes

None

Checklist

• I have read the contribution guidelines.
• I have updated the documentation, if applicable.
• I have tested my change(s) in the test suite, and added new test cases where necessary.
• My code follows the Cortex project's prevailing coding style and conventions.

[johnhaddon]

Thanks Paul - this looks handy. Comments inline...

[johnhaddon]

I really like the symmetry of these two functions - I think it makes it very clear that we're serialising to a string and deserialising back.

[johnhaddon]

Do we need this constructor as well as fromString()? I don't see the need to have two ways of achieving the same thing, and the constructor's semantics seem much less clear. Looking at MurmurHash( variable ) in code I think you could be easily forgiven for thinking that it was equivalent to MurmurHash h; h.append( variable ).

[proberts-cinesite]

The existing __repr__ function in the python binding (line 52 of MurmurHashBinding.cpp) seems to assume it already exists and produces IECore.MurmurHash( hash.toString() ) as the python representation of a MurmurHash object.

[johnhaddon]

This is in the section for an already-released version, but needs to be in a new section. If you want the feature to be released in the next 10.4.x version, the PR also needs to be targeted to the RB-10.4 branch.

[proberts-cinesite]

retargeted to RB-10.4

[johnhaddon]

I think static MurmurHash fromString(); might provide slightly better ergonomics, so this could just be a one-line hs = MurmurHash.fromString( s ).

[proberts-cinesite]

done

[johnhaddon]

Thanks Paul. I'm still a bit uneasy about this string constructor, but at least the new sanity check and exception will catch most invalid uses. Could you squash everything down ready to merge please? You could also move the Improvements section about the Build section in Changes - we try to order things so the more interesting stuff is at the top...

[proberts-cinesite]

all done