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https://issues.apache.org/jira/browse/CLEREZZA-510?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13032288#comment-13032288
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Henry Story edited comment on CLEREZZA-510 at 5/12/11 7:42 AM:
---------------------------------------------------------------
I put it in
./rdf.scala.utils/src/main/scala/org/apache/clerezza/rdf/scala/utils/EasyGraph.scala
because I am starting to need it in other packages, not just the test package.
Some issues I have thought of when building and using this (usage helps the
most in understanding)
1. It could be merged with SimpleGraphNode
(but I thought it would be better to do that, when this class is well
understood, as I don't want to by accident make Simple complex)
2. It coud be more efficient. EasyGraph could have lazy val references to
instances of the inner Predicate and InversePredicate classes
which would have var references to the UriRefs that identify them, so
that it does not need to create a new object on every statement creation. This
would restrict the writing of such graph to a single threads
though.
3. one should look at using -- and --> perhaps for arrows, and so also <--
and -- for reverse arrows, as those are easier to type, and available on more
platforms. On the other hand one has to watch out about operator precedence
rules. From the Scala Reference book
<blockquote>
The precedence of an infix operator is determined by the operator’s first
character.
Characters are listed below in increasing order of precedence, with
characters on
the same line having the same precedence.
(all letters)
|
^
&
< >
= !
:
+ -
* / %
(all other special characters)
That is, operators starting with a letter have lowest precedence, followed
by operators
starting with ‘|’, etc.
There’s one exception to this rule, which concerns assignment
operators(§6.12.4).
The precedence of an assigment operator is the same as the one of simple
assignment
(=). That is, it is lower than the precedence of any other operator.
The associativity of an operator is determined by the operator’s last
character. Operators
ending in a colon ‘:’ are right-associative. All other operators are
leftassociative.
</blockquote>
4. If one is to use unicode symbols, there may be more appropriate ones
that I have not noticed.
was (Author: bblfish):
I put it in
./rdf.scala.utils/src/main/scala/org/apache/clerezza/rdf/scala/utils/EasyGraph.scala
because I am starting to need it in other packages, not just the test package.
Some issues I have thought of when building and using this (usage helps the
most in understanding)
1. It could be merged with SimpleGraphNode
(but I thought it would be better to do that, when this class is well
understood, as I don't want to by accident make Simple complex)
2. It coud be more efficient. EasyGraph could have lazy val references to
instances of the inner Predicate and InversePredicate classes
which would have var references to the UriRefs that identify them, so
that it does not need to create a new object on every statement creation. This
would restrict the writing of such graph to a single threads
though.
3. one should look at using -- and --> perhaps for arrows, and so also <--
and -- for reverse arrows, as those are easier to type, and available on more
platforms. On the other hand one has to watch out about operator precedence
rules. From the Scala Reference book
<blockquote>
The precedence of an infix operator is determined by the operator’s first
character.
Characters are listed below in increasing order of precedence, with
characters on
the same line having the same precedence.
(all letters)
|
^
&
< >
= !
:
+ *
/ %
(all other special characters)
That is, operators starting with a letter have lowest precedence, followed
by operators
starting with ‘|’, etc.
There’s one exception to this rule, which concerns assignment
operators(§6.12.4).
The precedence of an assigment operator is the same as the one of simple
assignment
(=). That is, it is lower than the precedence of any other operator.
The associativity of an operator is determined by the operator’s last
character. Operators
ending in a colon ‘:’ are right-associative. All other operators are
leftassociative.
</blockquote>
4. If one is to use unicode symbols, there may be more appropriate ones
that I have not noticed.
> DSL for writing RDF elegantly
> -----------------------------
>
> Key: CLEREZZA-510
> URL: https://issues.apache.org/jira/browse/CLEREZZA-510
> Project: Clerezza
> Issue Type: New Feature
> Reporter: Henry Story
> Assignee: Henry Story
> Attachments: NiceLookingGraphInScala.png
>
>
> Writing RDF like
> graph.add(new TripleImp(Subj,rel,obj))
> is tedious to read and to write and makes every thing seem really heavy. Make
> it look good.
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