Re: [Springframework-developer] Spring Enhancement

[Mike Cannon-B. <mi...@at...>]

Colin,

Hrm - I think an expr tag would be a start, but really I don't see why you
can't just make everything an expr? I mean - what are the backward
compatibility issues?

Or else, have an attribute maybe like type="expr" which indicates the body
of the tag is an expression to be evaluated? (The only real need for this I
think is in the case of performance parsing the file - but seeing as a
context is initialized relatively infrequently, I'm not sure this is such a
big issue?) 

Cheers,
Mike

On 7/12/03 2:49 AM, "Colin Sampaleanu" (col...@ex...) penned the words:

> I was planning to add (optional) OGNL support in about 2-6 weeks
> (depending on when we start working on 1.1 features. Now what I was
> going to do was a relatively transparent implementation, where a new
> <expr> element would be usable anywhere <value> now is, i.e.
> 
> <property name="whatever">
> <expr>ognl:an.ognl.expression</expr>
> </property>
> 
> Allowing usage of expression in existing elements, like <key>, would be
> possible, but has some implications in terms of backwards compatibility...
> 
> 
> Mike Cannon-Brookes wrote:
> 
>> Or an even better idea... how about supporting OGNL within the Spring config
>> files? (like Xwork does)
>> 
>> This would be _awesome_ and I just found a second use case for it (the very
>> minute Rob's email came in).
>> 
>> My use case - Maps.
>> 
>> The Map syntax is nice, but not very useful in practicality I'm finding as
>> the key and value of the map are usually related, for instance I often want
>> to put a list of referenced beans into a map, with ref.getName() (or some
>> method) called for the key.
>> 
>> At the moment I have to add a setBeans(List) method to my class, and then in
>> that setter iterate and add to a map - smelly!
>> 
>> If we allowed OGNL expressions, it would be very simple to do this in the
>> config file itself:
>> 
>> <property value="myMapProp">
>>  <map>
>>    <entry>
>>      <key>$referencedBean.name</key>
>>      <value><ref bean="referencedBean" /></value>
>>    </entry>
>> ... More entries
>>  </map>
>> </property>
>> 
>> I'm sure there are a million other places where OGNL would be useful too,
>> but AFAIK the above can't be done _without_ it?
>> 
>> Or have I just been at this desk far too long?
>> 
>> M
>> 
>> On 2/12/03 8:32 AM, "Rob Butler" (rob...@ve...) penned the
>> words:
>> 
>>  
>> 
>>> Spring now provides the ability to instantiate an object using either a
>>> JavaBean no arg constructor, or any normal Java constructor.  But it does
>>> not
>>> support calling methods.
>>> 
>>> Also, Spring requires that a class implement the InitializingBean interface
>>> if
>>> it needs to perform some "setup" work after the setters have all been
>>> called.
>>> This means that any class that has this need is tied to the Springframework.
>>> 
>>> What if the ability to call any arbitrary method was added to Spring?  Then
>>> users could call "afterPropertiesSet" to do "setup" work without having to
>>> implement the InitializingBean interface.  Ideally method calls could be in
>>> any order along with calls to setters.  Spring would then call each in
>>> order.
>>> Thus, allowing some setters to be called, then some methods, then more
>>> setters
>>> if necessary.  If this is not possible, then methods should be called after
>>> setters.
>>> 
>>> This would allow complete decoupling of classes from Spring.  The
>>> InitializingBean & BeanFactoryAware interfaces would no longer be needed
>>> (although could remain for backwards compatibility).  This would be very
>>> useful when contributing code to other projects that do not want to have a
>>> dependency on Spring.  Also, it would allow virtually any class used by
>>> /developed for  another IOC framework / lightweight container to be used in
>>> Spring.
>>> 
>>> Thoughts?
>>> 
>>> Later
>>> Rob
>>>    
>>> 
> 
> 
> 
> 
> 
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