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Reply-To: "Jakarta Commons Developers List" <commons-dev@jakarta.apache.org>
Date: Sun, 24 Nov 2002 23:43:04 +0000
Subject: Re: [BeanUtils] - some small fixes,
 plus a proposal for namespace resolutions
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Cc: "Rune Toalango Johannesen" <rune@toalango.com>
To: "Jakarta Commons Developers List" <commons-dev@jakarta.apache.org>
From: robert burrell donkin <robertburrelldonkin@blueyonder.co.uk>
In-Reply-To: <001901c293ef$a023e910$0300000a@TOSHIBA>
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hi

you'll find that different open source projects are managed differently.=20=

here at apache, nearly all of our development is done in the open on=20
public mailing lists.

so rather than discuss the issues you've raised, what i'm going to do is=20=

point you at the documents we've written to help people who want to=20
contribute. once you've read them, post again to commons-dev mailing so=20=

that everyone has a chance look at your ideas and (if they wish) comment=20=

on them.

you should start by browsing the web site and in particular read

http://jakarta.apache.org/site/getinvolved.html

if you want to submit some patches, then you might find this document=20
useful:

http://jakarta.apache.org/commons/patches.html

if you want to know about the apache software foundation, then browse

http://apache.org/foundation

hopefully these should answer most of your questions!

- robert

On Sunday, November 24, 2002, at 07:27 PM, Rune Toalango Johannesen =
wrote:

> Hi chaps,
>
> I have picked your addresses from the project.xml file of=20
> Jakarta-Commons-BeanUtils.
>
> I have never contributed to any open source projects before, so I am =
not=20
> quite sure about the procedure for commiting without "committer" =
status.=20
> I downloaded the attached files from CVS yesterday and filtered out =
only=20
> the files I have changed in the attached .zip file. A commit comment =
is=20
> also attached in the .txt file. Not a big change - general QA - mostly=20=

> for myself to get familiar with the way this works.
>
> <<...>> <<...>>
> All the unit tests worked fine after the changes. Please let me know =
if=20
> there is an easier way for non-commiters to commit proposals.
>
> I have used the BeanUtils as help classes in a project to accomplish =
the=20
> following:
>
> Once you have a number of classes, potentially nested into maps and=20
> arrays/lists, and you want to query this as a dedicated namespace, the=20=

> existing PropertyUtils comes to short. I also had a requirement to use=20=

> dots to separate the different elements in the namespace, regardles of=20=

> the underlying structure (map, bean, list, array).
>
> Example data structure:
>
> =95 	Hashtable containing two entries, "foo" and "bar", each having a =
List=20
> as their values.
> =95 	The lists contain various Person bean objects with properties =
that=20
> might return new beans, lists, maps or arrays
>
> Person {
> =A0=A0=A0=A0=A0=A0=A0 Person[] getChildren();
> =A0=A0=A0=A0=A0=A0=A0 Map getPhones();
> =A0=A0=A0=A0=A0=A0=A0 String getFirstName();
> =A0=A0=A0=A0=A0=A0=A0 String getLastName();
> }
>
> Example queries for this "namespace" structure:
>
> =95 	foo.0.children.0.lastName
> =95 	foo.5.firstName
> =95 	bar.3.phones.work.extension
>
> A significant benefit of this approach is that the underlying =
structure=20
> is not that relevant to the author of the queries. We could for =
instance=20
> imagine that the above-mentioned getPhones() method returned a Phones=20=

> bean instead of the Map:
>
> Phone {
> =A0=A0=A0=A0=A0=A0=A0 PhoneNumber getWork();
> =A0=A0=A0=A0=A0=A0=A0 PhoneNumber getHome();
> =A0=A0=A0=A0=A0=A0=A0 PhoneNumber getMobile();
> }
>
> PhoneNumber {
> =A0=A0=A0=A0=A0=A0=A0 String getExtension();
> =A0=A0=A0=A0=A0=A0=A0 String getCountryCode();
> =A0=A0=A0=A0=A0=A0=A0 String getNumber();
> }
>
> The last example query wouldn't need to change, and the author doesn't=20=

> have to know what the actual data structure is.
>
> The missing features of the current PropertyUtils to accomplish this =
are:
>
> =95 	Support for List, Array and Map implementations as "standalone"=20=

> structures outside bean properties in a nested set of objects
> =95 	A proactive introspection of the "current" object ("Oh, I have a =
Map,=20
> then the next element in the query must be the key")
>
> The latter is essential to be able to use one unified delimitor in the=20=

> queries. With the current PropertyUtils the query will fail if the =
query=20
> contains "(aMapKey)" but the underlying structure isn't a map.
>
> I have gathered this feature in a class named ObjectUtils ("object"=20
> because List, Map and Array implementations are not recognized as =
beans).=20
> Additional features in this class include:
>
> =95 	Nested keys: =
"a.key.with.{a.nested.key}.lots.of.dots.{another.one}".=20
> The sub-keys in the {} are separate queries within the same =
"namespace"=20
> object
> =95 	A toString() method to print the whole content of nested bean=20
> properties, lists, maps and arrays:
>
> foo.0.children.0.lastName =3D [Smith]
> foo.5.firstName =3D [John]
> bar.3.phones.work.extension =3D [45]
>
> The last method is a bit tricky once the structure contains circular=20=

> references=85 you can imagine how fast a recursive method eats up the=20=

> memory once a child bean references its parent, and vica versa. I am=20=

> working on a solution to prevent this. The toString() method is useful=20=

> during development time for debug purposes ("Give me the content of =
the=20
> session object right now"), and it also helps authors of queries =
because=20
> you can copy and paste the available keys directly.
>
> Do you think this additional feature is suitable within the BeanUtils=20=

> package? I could adapt the code conventions and logging facilities and=20=

> provide you with the ObjectUtils class for a future release if you =
think=20
> it suits into the framework. The class doesn't contain support for=20
> DynaBeans yet, but I think that could easily be added. I have also =
been=20
> reluctant to throw exceptions - if the query doesn't find the "target"=20=

> value it simply returns null.
>
> To accomplish the nested keys I used some StringUtils from the=20
> Commons-Lang package. I guess the introduction of new "external"=20
> dependencies is not that popular, but the alternative is to clone a =
piece=20
> of code. Any opinions about this? Struts has a lot of "external" =
Jakarta=20
> dependencies already, and a danger is of course the potential version=20=

> conflicts this might cause once you have too many inter-dependencies.
>
> I'll sign up for the Jakarta-Commons email list shortly - I guess that =
is=20
> where these discussions should find place?
>
> Keep up the good work!
>
>
> Best regards
>
> Rune Toalango Johannesen
>
>


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