Re: [beanutils] GenericComparator -I have a project I'd like to contribute to Jakarta Commons.

[Stephen Colebourne <sc...@btopenworld.com>]

Tagged to the right commons project.
You might want to look at how beanutils accesses bean properties - its
slightly different to how you do it.

Stephen

----- Original Message -----
From: "Wickus Martin" <wi...@exinet.co.za>
> A while back I wrote a generic comparator for Java objects and called it
> GComp. We've been using it internally at the company where I work, but I
was
> wondering if it might not be of value to the commons project.
>
> Typically Java programmers create a custom Comparator implementation for
> every comparison scenario they encounter. GComp on the other hand can
> compare objects according to complex criteria based on a simple expression
> that explains how the objects should be compared. Great time saver and
> prevents problem of many small comparator classes bloating the code base.
>
> Usage scenario:
>
> Lets say we have a class called Customer with methods to access the first
> name and last name. Lets also say we have a class called Order that holds
a
> reference to an instance of Customer.
>
> To compare orders according to the customer surname (ascending) we could
> create the following comparator:
>
> new GComp("getLastName");
>
> To compare a collection of orders according to the customer last name
> (ascending) and then first name (descending) for those customers with the
> same last name we could create the following comparator:
>
> new
>
GComp("getCustomer.getLastName@order=asc|getCustomer.getFirstName@order=desc
> ");
>
> To order null values last and ignore case we could create:
>
> new
>
GComp("getCustomer.getLastName.toLowerCase@order=asc,nulls=last|getCustomer.
> getFirstName.toLowerCase@order=desc,nulls=last");
>
>
> The above code only orders on string objects, but all objects implementing
> the comparable interface is supported as is primitive types.
>
> Currently GComp uses commons-logging to output debugging information if
> commons logging is found on the classpath.
>
> I'm happy to donate the code for further study. Let me know.
>
> Keep well,
> Wickus Martin
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: commons-dev-unsubscribe@jakarta.apache.org
> For additional commands, e-mail: commons-dev-help@jakarta.apache.org
>


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Re: [beanutils] GenericComparator -I have a project I'd like to contribute to Jakarta Commons.

[robert burrell donkin <ro...@blueyonder.co.uk>]

i've been wanting to factor out the bean query language (so that users can 
plug-in alternative implementations) for ages now. maybe this could 
provide some momentum for this change.

- robert

On Thursday, October 2, 2003, at 09:39 PM, Henri Yandell wrote:

>
> BeanComparator does parts of this too, but doesn't have the EL-style
> language that Wickus has.
>
> Hen
>
> On Thu, 2 Oct 2003, Stephen Colebourne wrote:
>
>> Tagged to the right commons project.
>> You might want to look at how beanutils accesses bean properties - its
>> slightly different to how you do it.
>>
>> Stephen
>>
>> ----- Original Message -----
>> From: "Wickus Martin" <wi...@exinet.co.za>
>>> A while back I wrote a generic comparator for Java objects and called it
>>> GComp. We've been using it internally at the company where I work, but 
>>> I
>> was
>>> wondering if it might not be of value to the commons project.
>>>
>>> Typically Java programmers create a custom Comparator implementation for
>>> every comparison scenario they encounter. GComp on the other hand can
>>> compare objects according to complex criteria based on a simple 
>>> expression
>>> that explains how the objects should be compared. Great time saver and
>>> prevents problem of many small comparator classes bloating the code 
>>> base.
>>>
>>> Usage scenario:
>>>
>>> Lets say we have a class called Customer with methods to access the 
>>> first
>>> name and last name. Lets also say we have a class called Order that 
>>> holds
>> a
>>> reference to an instance of Customer.
>>>
>>> To compare orders according to the customer surname (ascending) we could
>>> create the following comparator:
>>>
>>> new GComp("getLastName");
>>>
>>> To compare a collection of orders according to the customer last name
>>> (ascending) and then first name (descending) for those customers with 
>>> the
>>> same last name we could create the following comparator:
>>>
>>> new
>>>
>> GComp("getCustomer.getLastName@order=asc|getCustomer.getFirstName@order=
>> desc
>>> ");
>>>
>>> To order null values last and ignore case we could create:
>>>
>>> new
>>>
>> GComp("getCustomer.getLastName.toLowerCase@order=asc,nulls=last|getCustomer.
>>> getFirstName.toLowerCase@order=desc,nulls=last");
>>>
>>>
>>> The above code only orders on string objects, but all objects 
>>> implementing
>>> the comparable interface is supported as is primitive types.
>>>
>>> Currently GComp uses commons-logging to output debugging information if
>>> commons logging is found on the classpath.
>>>
>>> I'm happy to donate the code for further study. Let me know.
>>>
>>> Keep well,
>>> Wickus Martin
>>>
>>>
>>> ---------------------------------------------------------------------
>>> To unsubscribe, e-mail: commons-dev-unsubscribe@jakarta.apache.org
>>> For additional commands, e-mail: commons-dev-help@jakarta.apache.org
>>>
>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: commons-dev-unsubscribe@jakarta.apache.org
>> For additional commands, e-mail: commons-dev-help@jakarta.apache.org
>>
>
>
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Re: [beanutils] GenericComparator -I have a project I'd like to contribute to Jakarta Commons.

[Henri Yandell <ba...@generationjava.com>]

BeanComparator does parts of this too, but doesn't have the EL-style
language that Wickus has.

Hen

On Thu, 2 Oct 2003, Stephen Colebourne wrote:

> Tagged to the right commons project.
> You might want to look at how beanutils accesses bean properties - its
> slightly different to how you do it.
>
> Stephen
>
> ----- Original Message -----
> From: "Wickus Martin" <wi...@exinet.co.za>
> > A while back I wrote a generic comparator for Java objects and called it
> > GComp. We've been using it internally at the company where I work, but I
> was
> > wondering if it might not be of value to the commons project.
> >
> > Typically Java programmers create a custom Comparator implementation for
> > every comparison scenario they encounter. GComp on the other hand can
> > compare objects according to complex criteria based on a simple expression
> > that explains how the objects should be compared. Great time saver and
> > prevents problem of many small comparator classes bloating the code base.
> >
> > Usage scenario:
> >
> > Lets say we have a class called Customer with methods to access the first
> > name and last name. Lets also say we have a class called Order that holds
> a
> > reference to an instance of Customer.
> >
> > To compare orders according to the customer surname (ascending) we could
> > create the following comparator:
> >
> > new GComp("getLastName");
> >
> > To compare a collection of orders according to the customer last name
> > (ascending) and then first name (descending) for those customers with the
> > same last name we could create the following comparator:
> >
> > new
> >
> GComp("getCustomer.getLastName@order=asc|getCustomer.getFirstName@order=desc
> > ");
> >
> > To order null values last and ignore case we could create:
> >
> > new
> >
> GComp("getCustomer.getLastName.toLowerCase@order=asc,nulls=last|getCustomer.
> > getFirstName.toLowerCase@order=desc,nulls=last");
> >
> >
> > The above code only orders on string objects, but all objects implementing
> > the comparable interface is supported as is primitive types.
> >
> > Currently GComp uses commons-logging to output debugging information if
> > commons logging is found on the classpath.
> >
> > I'm happy to donate the code for further study. Let me know.
> >
> > Keep well,
> > Wickus Martin
> >
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: commons-dev-unsubscribe@jakarta.apache.org
> > For additional commands, e-mail: commons-dev-help@jakarta.apache.org
> >
>
>
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> To unsubscribe, e-mail: commons-dev-unsubscribe@jakarta.apache.org
> For additional commands, e-mail: commons-dev-help@jakarta.apache.org
>


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