Hi,
In TP4, Bytecode instruction arguments can be Bytecode. Well of course, this is
like in TP3 --- nested traversals (union(), repeat(), etc.). However! —
Bytecode can also be used for singleton arguments. For instance:
has(“name”,select(“a”).value(“name”))
is(gt(select(“a”).out().count()))
Thus, what were “constant” arguments in TP3 can now be “dynamic”
(traversal-determined) arguments.
Because arguments can be traversals, various steps are starting to blend into
each other:
is(gt(select(“a”))) <=> where(gt(“a”))
Now, we can keep where() in Gremlin, but at the bytecode level, it can just
translate to an is() instruction. However, perhaps we can remove one from the
Gremlin language…?
Another thing that I want to clean up in Gremlin4 is select(). We have
overloaded this step to the extreme where it can:
1. select a value from the incoming Map.
2. select an object from the Path history.
3. select a sideEffect from global side-effects.
I think we should split it up:
1. select() for getting value from incoming Map.
2. path() for getting an object from a Path history.
3. … I don’t know if we will have global side-effects in TP4.
Thus,
g.V().as(“a”).out().as(“b”).select(“a”,”b”).by(“name”)
would become…
g.V().as(“a”).out().as(“b’).path(“a”,”b”).by(“name”)
Next, if we assume that Vertex and Edge are “MapLike”, then what is the
difference between values() and select()?
g.V().values(“name”)
g.V().select(“name”)
Any thoughts on the future of is(), where(), select(), and path() would be
appreciated.
Thanks,
Marko.
http://markorodriguez.com
