Help with trying/understanding Sideeffect in Java

[pShah]

A blog post by Marko: On the Nature of Pipes

There are side-effect pipes which seem pretty intersting.

However, I get confused with "it" when trying this example in pure Java:
g.v(1).sideEffect{x=it}.out('created').in('created').filter{it != x}

How can we specify in java to say "x=it" and then use it later in the filter "it != x" ?

I have been able to do some of the basic filter pipes and I get that it can be vertex or string, depending on what the previous pipe was, but how do you store something and use it again?

Any help will be great.


[pShah]

I managed to solve it, but appreciate any guidance anyone has.

What I was missing was declaring the variable on the outside.

If anyone needs it:

        List<String> output = new ArrayList();
        final List<Vertex> temp = new ArrayList();
       
        IndexableGraph g = TinkerGraphFactory.createTinkerGraph();
           
        output = new GremlinPipeline(g.getVertex(1))
        .sideEffect(
                new PipeFunction<Vertex, Vertex>() {
                    public Vertex compute(Vertex it) {
                        temp.add(it);
                        return it;
                    }
                }
                )
        .out("created")
        .in("created")
        .filter(
                new PipeFunction<Vertex, Boolean>() {
                    public Boolean compute(Vertex it) {
                        if (temp.contains(it))
                            return false;
                        else
                            return true;
                    }
                }
                )
        .toList();
       
       
        System.out.println(output);

[Pierre De Wilde]

Hey,

In Gremlin Groovy:

g.v(1).sideEffect{x=it}.out('created').in('created').filter{it != x}

may be expressed as

g.v(1).store(x).out('created').in('created').except(x)

assuming x = []

HTH,

Pierre

[pShah]

Thanks Pierre