Re: [Springframework-developer] bean factory scope question

[Steven D. <ste...@gm...>]

James,

I don't want to reply on the mailing list on this subject. I'm working
on a tool that introduces processing logic to Spring. I'll call this
tool James for now because I don't want to give away the name yet.
Your example would be:

<bean id="usermgmt" class="...">
   <property name="emailService">
      <bean parent="james.Defined">
         <property
name="beanName"><value>usermgmt.emailService</value></property>
         <property name="do">
            <bean parent="james.Return">
                <property name="value">
                    <ref bean="usermgmt.emailService"/>
                </property>
            </bean>
         </property>
      </bean>
   </property>
</bean>

The tools is part of a bigger whole but it will be available within a
month I think. It's nice to see other people may have use for it :-)
Actually the Defined and Return beans don't exist yet but your mail
gave me the inspiration :-)

Steven


On Fri, 7 Jan 2005 10:55:48 -0500, James Cook <jim...@do...> wrote:
> Is there a way to define a bean property that is "optional"? If it exists,
> wire it up, otherwise let it remain null? This can be useful when creating
> Spring-enabled components.
> 
> For example, I may have an email bean wired to a user management bean.
> 
> <bean id="usermgmt" class="my.UserManagement">
>         <property name="emailService">
>                 <ref bean="usermgmt.emailService" />
>         </property>
> </bean>
> 
> If the user provided a bean with a name of "usermgmt.emailService" my class
> would use this service to send emails. If the bean was not provided, I would
> skip sending emails or maybe use a default implementation.
> 
> Perhaps an optional attribute would help?
>         <property name="emailService" optional="true">
> 
> I think this will become a bigger deal as people start componentizing there
> spring modules.
> 
> One way to solve this now is provide the bean name instead of a bean
> reference to the UserManagement bean. Then this bean is responsible for
> looking up the bean reference and handling it accordingly whether it exists
> or not. This is more in the style of JNDI lookups and not very IoC, plus it
> makes my beans more spring aware than I would like.
> 
> > -----Original Message-----
> > Beans that are supposed to be available for references by name indeed need
> > to be defined at the root level. Inner beans are always anonymous and
> > usually don't carry a name. Defining a name for them only adds value if
> > they
> > are aware of their own name (BeanNameAware).
> 
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