[GitHub] tinkerpop pull request #647: TINKERPOP-1708: Add a "Note on Scopes" document

[dkuppitz <gi...@git.apache.org>]

Github user dkuppitz commented on a diff in the pull request:

    https://github.com/apache/tinkerpop/pull/647#discussion_r125266019
  
    --- Diff: docs/src/reference/the-traversal.asciidoc ---
    @@ -2574,6 +2574,58 @@ possible at the current, local vertex. What it can't compute without referencing
     into a barrier collection. When there are no more traversers at the local vertex, the barriered traversers are the
     messages that are propagated to remote vertices for further processing.
     
    +[[a-note-on-scopes]]
    +A Note on Scopes
    +----------------
    +
    +The `Scope` enum has two constants: `Scope.local` and `Scope.global`. Scope determines whether the particular step
    +being scoped is with respects to the current object (`local`) at that step or to the entire stream of objects up to that
    +step (`global`).
    +
    +[gremlin-groovy,modern]
    +----
    +g.V().has('name','marko').out('knows').count() <1>
    +g.V().has('name','marko').out('knows').fold().count() <2>
    +g.V().has('name','marko').out('knows').fold().count(local) <3>
    +g.V().has('name','marko').out('knows').fold().count(global) <4>
    +----
    +
    +<1> Marko knows 2 people.
    +<2> A list of Marko's friends is created and thus, one object is counted (the single list).
    +<3> A list of Marko's fiends is created and a `local`-count yields the number of objects in that list.
    +<4> `count(global)` is the same as `count()` as the default behavior for most scoped steps is `global`.
    +
    +The steps that support scoping are:
    +
    +* <<count-step,`count()`>>: count the local collection or global stream.
    +* <<dedup-step, `dedup()`>>: dedup the local collection of global stream.
    +* <<max-step, `max()`>>: get the max value in the local collection or global stream.
    +* <<mean-step, `mean()`>>: get the mean value in the local collection or global stream.
    +* <<min-step, `min()`>>: get the min value in the local collection or global stream.
    +* <<order-step,`order()`>>: order the objects in the local collection or global stream.
    +* <<range-step, `range()`>>: clip the local collection or global stream.
    +* <<sample-step, `sample()`>>: sample objects from the local collection or global stream.
    +* <<tail-step, `tail()`>>: get the tail of the objects in the local collection or global stream.
    --- End diff --
    
    `limit()` is missing. I know it's `RangeStep`, but in the user docs we describe `range()` and `limit()` as different steps.


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