How doe the "." notations in Query & GremlinPipeline work in Java

[pShah]

Hi,
  My primary background is Database programming.  I have done some C# as well and I thought the "." notation used where extension methods.

  But I couldn't understand from the source code of "blueprints" how this works?

  Can someone expalin it using the "Query.java" as the example and how the Edge/Vertex knows what appropriate method goes after the "."

Thanks

[Marko Rodriguez]

Hi,

Using that notation to invoke a method which simply returns the object again is called "the fluent style." (I believe that is the generally accepted term). It is possible to do this in most languages.

http://en.wikipedia.org/wiki/Fluent_interface

Thus, when you do:

GremlinPipeline.out()

You are taking the GremlinPipeline and adding an OutPipe to it. The return of out() is the GremlinPipeline with the new OutPipe on it. As such, you can continuously chain methods.

GremlinPipeline.out().has().in().property()....

Likewise for objects like Blueprints' Query.

I hope that is clear,

Marko.

http://markorodriguez.com

[pShah]

It does help.  I just have to look at the code more carefully to get a better understanding.

It primarily confuses me becuas the "TinkerVertex.java" class has "query" as a method but not the "has", so how does the Vertex instance know that it can use "has"

[Marko Rodriguez]

Study the code. 

Marko.

http://markorodriguez.com

[pShah]

That's the plan.

[Marko Rodriguez]

Cool. :).

Marko.

http://markorodriguez.com

[Alexandre Vallette]

sorry for my stupid question but once you get the pipeline list like:

com.tinkerpop.gremlin.java.GremlinPipeline[Nothing,com.tinkerpop.blueprints.Edge] = [StartPipe, InEdgesPipe(parent)]

how do you evaluate it?

I'm confused because in gremlin this evaluation is automatic

[Viktoras Veitas]

Sometimes I apply .toList() method:
http://www.tinkerpop.com/docs/javadocs/gremlin/2.3.0/com/tinkerpop/gremlin/java/GremlinPipeline.html#toList%28%29

Viktoras

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