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comp.lang.ruby

Ruby Data Structure Query Abstractions/Patterns

Nicholas Van Weerdenburg

1/5/2005 6:26:00 PM

Hi all,

I've written a small ruby application that uses YAML and the
associated hash/array Ruby structure.

I am now looking to do some query-like actions on the basic ruby data
structure. I'm wondering if there are any packages of
query-abstractions that make sense for Ruby in a generalized sort-of
way. E.g. XPath and XQuery for XML, SQL for RDMS, etc.

Currently I've written my structure-parsing code with a few of my
cases, and I'm starting to refactor with blocks and lambdas in order
to keep duplication low and offer an easily configurable higher-level
of abstraction. Now the code is starting to pressure me to create a
simple query language. Maybe I should go to a ruby db or sqlite, but I
expect I ultimately only need the most basic functionality.

Any suggestions or recommendations?

Thanks,
Nick
--
Nicholas Van Weerdenburg
15 Answers

Petite Abeille

1/5/2005 6:41:00 PM

0


On Jan 05, 2005, at 19:26, Nicholas Van Weerdenburg wrote:

> Any suggestions or recommendations?

Not quite sure how well this would fit with Ruby, but you may want to
take a look at SODA [1] which could be used to query generic object
graphs.

In addition, you may want to consider EOQualifier for, er,
"inspiration":

http://developer.apple.com/documentation/WebObjects/Referenc...
webobjects/eocontrol/EOQualifier.html

Cheers,

PA.

[1] http://sodaquery.source...

Robert Klemme

1/5/2005 8:56:00 PM

0


"Nicholas Van Weerdenburg" <vanweerd@gmail.com> schrieb im Newsbeitrag
news:632154f705010510264aea7a10@mail.gmail.com...
> Hi all,
>
> I've written a small ruby application that uses YAML and the
> associated hash/array Ruby structure.
>
> I am now looking to do some query-like actions on the basic ruby data
> structure. I'm wondering if there are any packages of
> query-abstractions that make sense for Ruby in a generalized sort-of
> way. E.g. XPath and XQuery for XML, SQL for RDMS, etc.
>
> Currently I've written my structure-parsing code with a few of my
> cases, and I'm starting to refactor with blocks and lambdas in order
> to keep duplication low and offer an easily configurable higher-level
> of abstraction. Now the code is starting to pressure me to create a
> simple query language. Maybe I should go to a ruby db or sqlite, but I
> expect I ultimately only need the most basic functionality.
>
> Any suggestions or recommendations?

Another thought: maybe you can even use Ruby itself. I mean, one can
produce quite readable select expressions in Ruby and we have
Enumerable#all?, #any? etc. You might want to add some functionality for
recursive traversal though.

Kind regards

robert

Sam Roberts

1/6/2005 1:10:00 AM

0

Quoteing vanweerd@gmail.com, on Thu, Jan 06, 2005 at 03:26:22AM +0900:
> Hi all,
>
> I've written a small ruby application that uses YAML and the
> associated hash/array Ruby structure.

> I am now looking to do some query-like actions on the basic ruby data
> structure. I'm wondering if there are any packages of
> query-abstractions that make sense for Ruby in a generalized sort-of
> way. E.g. XPath and XQuery for XML, SQL for RDMS, etc.

This is why you might want to consider XML... then you can just USE
XPath.

Sam

>
> Currently I've written my structure-parsing code with a few of my
> cases, and I'm starting to refactor with blocks and lambdas in order
> to keep duplication low and offer an easily configurable higher-level
> of abstraction. Now the code is starting to pressure me to create a
> simple query language. Maybe I should go to a ruby db or sqlite, but I
> expect I ultimately only need the most basic functionality.
>
> Any suggestions or recommendations?
>
> Thanks,
> Nick
> --
> Nicholas Van Weerdenburg
>


Nicholas Van Weerdenburg

1/6/2005 4:14:00 AM

0

Thanks. Both links are very interesting.

Regards,
Nick


On Thu, 6 Jan 2005 03:41:23 +0900, PA <petite.abeille@gmail.com> wrote:
>
> On Jan 05, 2005, at 19:26, Nicholas Van Weerdenburg wrote:
>
> > Any suggestions or recommendations?
>
> Not quite sure how well this would fit with Ruby, but you may want to
> take a look at SODA [1] which could be used to query generic object
> graphs.
>
> In addition, you may want to consider EOQualifier for, er,
> "inspiration":
>
> http://developer.apple.com/documentation/WebObjects/Referenc...
> webobjects/eocontrol/EOQualifier.html
>
> Cheers,
>
> PA.
>
> [1] http://sodaquery.source...
>
>


--
Nicholas Van Weerdenburg

Nicholas Van Weerdenburg

1/6/2005 4:20:00 AM

0

On Thu, 6 Jan 2005 05:56:31 +0900, Robert Klemme <bob.news@gmx.net> wrote:
>
> "Nicholas Van Weerdenburg" <vanweerd@gmail.com> schrieb im Newsbeitrag
> news:632154f705010510264aea7a10@mail.gmail.com...
> > Hi all,
> >
> > I've written a small ruby application that uses YAML and the
> > associated hash/array Ruby structure.
> >
> > I am now looking to do some query-like actions on the basic ruby data
> > structure. I'm wondering if there are any packages of
> > query-abstractions that make sense for Ruby in a generalized sort-of
> > way. E.g. XPath and XQuery for XML, SQL for RDMS, etc.
> >
> > Currently I've written my structure-parsing code with a few of my
> > cases, and I'm starting to refactor with blocks and lambdas in order
> > to keep duplication low and offer an easily configurable higher-level
> > of abstraction. Now the code is starting to pressure me to create a
> > simple query language. Maybe I should go to a ruby db or sqlite, but I
> > expect I ultimately only need the most basic functionality.
> >
> > Any suggestions or recommendations?
>
> Another thought: maybe you can even use Ruby itself. I mean, one can
> produce quite readable select expressions in Ruby and we have
> Enumerable#all?, #any? etc. You might want to add some functionality for
> recursive traversal though.
>
> Kind regards
>
> robert
>
>

I like the idea of using Ruby, and have been extending my code in that
manner. However, XML becomes interesting soon because of it's DOM
traversal capabilities.

I'm also wondering if I'm missing some common Ruby/Perl/Python idiom
for handling in-memory data-structure traversal in a more abstract
way, but so far it doesn't look like it.

Does it make sense to have a general data-structure traversal/query
api in a language like Ruby?

Thanks,
Nick
--
Nicholas Van Weerdenburg

Nicholas Van Weerdenburg

1/6/2005 4:21:00 AM

0

On Thu, 6 Jan 2005 10:10:26 +0900, Sam Roberts <sroberts@uniserve.com> wrote:
> Quoteing vanweerd@gmail.com, on Thu, Jan 06, 2005 at 03:26:22AM +0900:
> > Hi all,
> >
> > I've written a small ruby application that uses YAML and the
> > associated hash/array Ruby structure.
>
> > I am now looking to do some query-like actions on the basic ruby data
> > structure. I'm wondering if there are any packages of
> > query-abstractions that make sense for Ruby in a generalized sort-of
> > way. E.g. XPath and XQuery for XML, SQL for RDMS, etc.
>
> This is why you might want to consider XML... then you can just USE
> XPath.
>
> Sam
>

This is looking like the most reasonable choice at the moment- though
not the most fun, so I may continue with a Ruby solution for now.

Thanks,
Nick

> >
> > Currently I've written my structure-parsing code with a few of my
> > cases, and I'm starting to refactor with blocks and lambdas in order
> > to keep duplication low and offer an easily configurable higher-level
> > of abstraction. Now the code is starting to pressure me to create a
> > simple query language. Maybe I should go to a ruby db or sqlite, but I
> > expect I ultimately only need the most basic functionality.
> >
> > Any suggestions or recommendations?
> >
> > Thanks,
> > Nick
> > --
> > Nicholas Van Weerdenburg
> >
>
>


--
Nicholas Van Weerdenburg

Sam Roberts

1/6/2005 4:58:00 AM

0

Quoteing vanweerd@gmail.com, on Thu, Jan 06, 2005 at 01:20:40PM +0900:
> On Thu, 6 Jan 2005 10:10:26 +0900, Sam Roberts <sroberts@uniserve.com> wrote:
> > Quoteing vanweerd@gmail.com, on Thu, Jan 06, 2005 at 03:26:22AM +0900:
> > > Hi all,
> > >
> > > I've written a small ruby application that uses YAML and the
> > > associated hash/array Ruby structure.
> >
> > > I am now looking to do some query-like actions on the basic ruby data
> > > structure. I'm wondering if there are any packages of
> > > query-abstractions that make sense for Ruby in a generalized sort-of
> > > way. E.g. XPath and XQuery for XML, SQL for RDMS, etc.
> >
> > This is why you might want to consider XML... then you can just USE
> > XPath.
> >
> > Sam
> >
>
> This is looking like the most reasonable choice at the moment- though
> not the most fun, so I may continue with a Ruby solution for now.

I don't know, what's not fun about XML?

Rant: for years the world fills up with adhoc 1/2 solutions to data
structuring, then people decide that reinventing the wheel is dumb, and
make XML, and start adding tons of useful tools to it, like query
languages. The folks come along and say 'its too big and complicated"
and start again... There will soon be a YPath (YAML query language),
mark my words!

Ok, I feel better.

That aside, it sounds kind of cool making a rubyish query language for
ruby data structures... maybe XPath from Rexml could actually be abused
for your purpose, or used to implement a similar language?

Have fun!
Sam

Its Me

1/6/2005 5:45:00 AM

0


"Sam Roberts" <sroberts@uniserve.com> wrote

> I don't know, what's not fun about XML?

Since you did not include any smileys ...

(1) Having a uniform and extensible concrete syntax for tree structures is
great
(2) Having a whole set of uniform manipulations on (1) is great
(3) Insisting on applying (1) to the concrete syntax of (2) is absurd and
the result, ugly

Just about every (computer) language has a natural underlying tree
structure, with lots of cross-tree links. So, should we now start to write
our Ruby using XML ?

Ok, I feel better now :-)

gabriele renzi

1/6/2005 11:28:00 AM

0

PA ha scritto:
>
> On Jan 05, 2005, at 19:26, Nicholas Van Weerdenburg wrote:
>
>> Any suggestions or recommendations?
>
>
> Not quite sure how well this would fit with Ruby, but you may want to
> take a look at SODA [1] which could be used to query generic object
> graphs.
>
> In addition, you may want to consider EOQualifier for, er, "inspiration":
>
> http://developer.apple.com/documentation/WebObjects/Referenc...
> webobjects/eocontrol/EOQualifier.html
>
> Cheers,
>
> PA.
>
> [1] http://sodaquery.source...
>


also, JXPath allows XPAth to be applied to generic graphs, maybe of interest

Robert Klemme

1/6/2005 12:33:00 PM

0


"Nicholas Van Weerdenburg" <vanweerd@gmail.com> schrieb im Newsbeitrag
news:632154f705010520196f99e845@mail.gmail.com...
> On Thu, 6 Jan 2005 05:56:31 +0900, Robert Klemme <bob.news@gmx.net> wrote:
>>
>> "Nicholas Van Weerdenburg" <vanweerd@gmail.com> schrieb im Newsbeitrag
>> news:632154f705010510264aea7a10@mail.gmail.com...
>> > Hi all,
>> >
>> > I've written a small ruby application that uses YAML and the
>> > associated hash/array Ruby structure.
>> >
>> > I am now looking to do some query-like actions on the basic ruby data
>> > structure. I'm wondering if there are any packages of
>> > query-abstractions that make sense for Ruby in a generalized sort-of
>> > way. E.g. XPath and XQuery for XML, SQL for RDMS, etc.
>> >
>> > Currently I've written my structure-parsing code with a few of my
>> > cases, and I'm starting to refactor with blocks and lambdas in order
>> > to keep duplication low and offer an easily configurable higher-level
>> > of abstraction. Now the code is starting to pressure me to create a
>> > simple query language. Maybe I should go to a ruby db or sqlite, but I
>> > expect I ultimately only need the most basic functionality.
>> >
>> > Any suggestions or recommendations?
>>
>> Another thought: maybe you can even use Ruby itself. I mean, one can
>> produce quite readable select expressions in Ruby and we have
>> Enumerable#all?, #any? etc. You might want to add some functionality for
>> recursive traversal though.
>>
>> Kind regards
>>
>> robert
>>
>>
>
> I like the idea of using Ruby, and have been extending my code in that
> manner. However, XML becomes interesting soon because of it's DOM
> traversal capabilities.
>
> I'm also wondering if I'm missing some common Ruby/Perl/Python idiom
> for handling in-memory data-structure traversal in a more abstract
> way, but so far it doesn't look like it.
>
> Does it make sense to have a general data-structure traversal/query
> api in a language like Ruby?

I'd say yes, but maybe only for certain types (DOM tree nodes) - not
necessarily for general Hash, Array and the like. OTOH you can cook up
something quite easily though:

class Object
def traverse() yield self end
end

module Enumerable
def traverse(&b)
each {|o| o.traverse(&b)}
end
end

class Hash
def traverse(&b)
each {|k,v| v.traverse(&b)}
end
end

Note that this does not take care of looks in the object graph. To do that,
you need to do a bit more:

class Object
def traverse(context = {}) context[self.id] ||= (yield self; true) end
end

module Enumerable
def traverse(context = {}, &b)
unless context[self.id]
context[self.id] = true
each {|o| o.traverse(context, &b)}
end
end
end

class Hash
def traverse(context = {}, &b)
unless context[self.id]
context[self.id] = true
each {|k,v| v.traverse(context, &b)}
end
end
end

Kind regards

robert