TINKERPOP-1887 Allow to use bindings in predicates

[eonpatapon]

Currently the python GLV does not allow to have bindings in predicates,
eg:

g.V().has('foo', lt(('bar', 10)))
g.V().has('foo', inside(('a', 10), ('b', 20)))

This patch fixes this

[davebshow]

This needs a test to demonstrate that it works. I haven't run the code yet, but what happens to the key value of the binding? Does this generate GraphSON with bindings, or just the values of the bindings?

[eonpatapon]

Yes, can you point me to the test suite ? I wasn't able to find it in the repo

[davebshow]

https://github.com/apache/tinkerpop/tree/master/gremlin-python/src/main/jython/tests

[eonpatapon]

After playing with the code and tests I'm realizing this does not work at all :)

Closing for now.

[davebshow]

There is a bit of a learning curve working with the Gremlin-Python source. Do you plan on giving this another try? If so, I will help you review. If not, let me know and I can give it a go.

[eonpatapon]

After playing a bit, I'm not sure if what I want to do is supported by the gremlin-server. Actually I don't know how the bytecode should look. Given the following query in python GLV: `g.V().has('foo', P.eq(('bar', 5)))` I translate it to the following bytecode: `[['V'], ['has', 'foo', ['eq', binding[bar=5]]]]` But this doesn't yield any results from the gremlin server. In tests I found some other form of query: `g.V().has('foo', ('bar', P.gt(5)))`, ie: `[['V'], ['has', 'foo', binding[bar=['eq', 5]]]]` But it doesn't yield any result either. Is there some bytecode reference somewhere to read more about it ? I didn't find any.