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Posted to user@commons.apache.org by Leandro Rodrigo Saad Cruz <le...@ibnetwork.com.br> on 2004/08/18 14:36:46 UTC
Collections HowTo
Hi all. Any directions on how to use Functors and Predicates ?
--
Leandro Rodrigo Saad Cruz
InterBusiness Tecnologia e Serviços
IB - www.ibnetwork.com.br
DB - www.digitalbrand.com.br
OJB - db.apache.org/ojb
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Re: Collections HowTo
Posted by Arnd Kohrs <ko...@acm.org>.
A very intriguing introduction to functors in Java can also be found
here: http://c2.com/cgi/wiki?BlocksInJava
That article is only weakly related to the functors which are
part of collections but rather related to sandbox/Functor.
Cheers,
Arnd.
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Re: Collections HowTo
Posted by Rodney Waldhoff <rw...@apache.org>.
There's a more comprehensive introduction to functors at
http://jakarta.apache.org/commons/sandbox/functor, with a number of
detailed examples at
http://cvs.apache.org/viewcvs.cgi/jakarta-commons-sandbox/functor/src/test/org/apache/commons/functor/example/.
- Rod
On Wed, 18 Aug 2004, Leandro Rodrigo Saad Cruz wrote:
> What is the concept behind Functor/Predicate/Transformer ?
>
> On Wed, 2004-08-18 at 10:44, matthew.hawthorne wrote:
>> Leandro Rodrigo Saad Cruz wrote:
>>> Hi all. Any directions on how to use Functors and Predicates ?
>>
>>
>> Hmm... maybe read the Javadoc?
>>
>> It's hard to respond to such a vague question, do you have a more
>> specific problem you're trying to solve?
>>
>> Basically, there are methods in CollectionUtils that take a collection
>> and a Functor/Predicate/Transformer as a parameter.
>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: commons-user-unsubscribe@jakarta.apache.org
>> For additional commands, e-mail: commons-user-help@jakarta.apache.org
> --
> Leandro Rodrigo Saad Cruz
> InterBusiness Tecnologia e Servi�os
> IB - www.ibnetwork.com.br
> DB - www.digitalbrand.com.br
> OJB - db.apache.org/ojb
> XINGU - xingu.sf.net
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: commons-user-unsubscribe@jakarta.apache.org
> For additional commands, e-mail: commons-user-help@jakarta.apache.org
>
>
Re: Collections HowTo
Posted by José Antonio Pérez Testa <ja...@indra.es>.
All that concepts are imported into java from Functional Programming
Languages such as Prolog or CAML.
IMHO they give a hand when working with Collections extracting the
process out of the loop.
For example, if you want to add all the elements of a List you only have
to define the add process and delegate to the Functor the loop itself.
When you have a list of some type and need a list of some other type
objects you only define the Transformer,
and if you want to select objects from a Collection based on some
criteria, you have to code the criteria , pass it to a Functor and
you'll have in return a new list with ONLY those objects.
Is another just another look into programming!
Leandro Rodrigo Saad Cruz wrote:
>What is the concept behind Functor/Predicate/Transformer ?
>
>On Wed, 2004-08-18 at 10:44, matthew.hawthorne wrote:
>
>
>>Leandro Rodrigo Saad Cruz wrote:
>>
>>
>>>Hi all. Any directions on how to use Functors and Predicates ?
>>>
>>>
>>Hmm... maybe read the Javadoc?
>>
>>It's hard to respond to such a vague question, do you have a more
>>specific problem you're trying to solve?
>>
>>Basically, there are methods in CollectionUtils that take a collection
>>and a Functor/Predicate/Transformer as a parameter.
>>
>>
>>---------------------------------------------------------------------
>>To unsubscribe, e-mail: commons-user-unsubscribe@jakarta.apache.org
>>For additional commands, e-mail: commons-user-help@jakarta.apache.org
>>
>>
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Re: Collections HowTo
Posted by Leandro Rodrigo Saad Cruz <le...@ibnetwork.com.br>.
What is the concept behind Functor/Predicate/Transformer ?
On Wed, 2004-08-18 at 10:44, matthew.hawthorne wrote:
> Leandro Rodrigo Saad Cruz wrote:
> > Hi all. Any directions on how to use Functors and Predicates ?
>
>
> Hmm... maybe read the Javadoc?
>
> It's hard to respond to such a vague question, do you have a more
> specific problem you're trying to solve?
>
> Basically, there are methods in CollectionUtils that take a collection
> and a Functor/Predicate/Transformer as a parameter.
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: commons-user-unsubscribe@jakarta.apache.org
> For additional commands, e-mail: commons-user-help@jakarta.apache.org
--
Leandro Rodrigo Saad Cruz
InterBusiness Tecnologia e Serviços
IB - www.ibnetwork.com.br
DB - www.digitalbrand.com.br
OJB - db.apache.org/ojb
XINGU - xingu.sf.net
---------------------------------------------------------------------
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Re: Collections HowTo
Posted by "matthew.hawthorne" <ma...@apache.org>.
Leandro Rodrigo Saad Cruz wrote:
> Hi all. Any directions on how to use Functors and Predicates ?
Hmm... maybe read the Javadoc?
It's hard to respond to such a vague question, do you have a more
specific problem you're trying to solve?
Basically, there are methods in CollectionUtils that take a collection
and a Functor/Predicate/Transformer as a parameter.
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