Am 26.08.2013 16:18, schrieb Phil Steitz: > > > On Aug 26, 2013, at 7:38 PM, Oliver Heger <oliver.he...@oliver-heger.de> > wrote: > >> Am 25.08.2013 18:45, schrieb Adrian Crum: >>> +1 >>> >>> -Adrian >>> >>> On 8/25/2013 9:26 AM, James Carman wrote: >>>> AtomicReference? >> >> There are multiple aspects here. One is the safe publishing of a value >> written into the member field. This can be achieved by atomic >> references, synchronization, or a volatile field. >> >> The other aspect is that such a field of a static utility class is >> pretty global. You cannot have different values for different threads. >> >> So the question is, is it good design to have static utility classes >> with state? > > Excellent point. The key question to ask is are there use cases where > different threads in the same JVM are really going to want different default > factories. I wonder if any actual user of the current code has ever wanted > this. > In this special case, I *assume* that there are hardly any concrete use cases, but of course, we cannot be sure.
However, there may be other examples in [configuration]. Would it make sense to be homogeneous here, i.e. use the same design principles for all classes? Oliver > Phil >> >> For users, it may be more convenient to simply access functionality >> through static methods, especially if the default values for static >> member fields are reasonable for most use cases. However, such a design >> makes it impossible to use the represented functionality with different >> settings in parallel. >> >> Also, I am not sure whether complex class loader scenarios (e.g. an >> application server or an OSGi container) may cause problems with the >> static approach. >> >> Oliver >> >>>> >>>> On Sunday, August 25, 2013, Phil Steitz wrote: >>>> >>>>> On 8/24/13 11:33 AM, Oliver Heger wrote: >>>>>> Hi all, >>>>>> >>>>>> regarding a principle design question I would like to get your opinion: >>>>>> >>>>>> In [configuration] there are a few static utility classes. One of them >>>>>> is BeanHelper which supports the creation of beans from configuration >>>>>> data. The actual bean creation is done by a BeanFactory which can be >>>>>> configured using the static (currently unsynchronized) >>>>>> setDefaultBeanFactory() method. >>>>>> >>>>>> Sebb stated correctly that this approach is thread-hostile [1]. An >>>>>> alternative could be to make BeanHelper a non-static class which can be >>>>>> instantiated and configured per instance. This would be more flexible >>>>>> and would also simplify testing of client code (just pass in a mock >>>>>> object). The drawback is that clients now always would have to >>>>>> create an >>>>>> instance, so the API becomes slightly more verbose - in fact, most >>>>>> clients will probably never have the requirement to change the default >>>>>> bean factory. >>>>>> >>>>>> So, the question is, what do you prefer? The static approach like >>>>>> Object myBean = BeanHelper.createBean(...); >>>>>> >>>>>> or using an instance as in >>>>>> BeanHelper helper = new BeanHelper(myFactory); >>>>>> // or use no-args ctor for default factory >>>>>> Object myBean = helper.createBean(...); >>>>> Personally, I would like the static method better as a user. >>>>> Synchronizing access to the static factory field would seem to fix >>>>> the problem unless I am missing something. Also, I would not expect >>>>> lots of concurrent access to the getter/setter for this field in >>>>> normal use cases , so the performance overhead of the sync would be >>>>> immaterial. Having the setter there may also be a little easier for >>>>> dependency injection. >>>>> >>>>> Phil >>>>>> TIA >>>>>> Oliver >>>>>> >>>>>> [1] https://issues.apache.org/jira/browse/CONFIGURATION-486 >>>>>> >>>>>> --------------------------------------------------------------------- >>>>>> To unsubscribe, e-mail: >>>>>> dev-unsubscr...@commons.apache.org<javascript:;> >>>>>> For additional commands, e-mail: >>>>>> dev-h...@commons.apache.org<javascript:;> >>>>> >>>>> --------------------------------------------------------------------- >>>>> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org >>>>> <javascript:;> >>>>> For additional commands, e-mail: >>>>> dev-h...@commons.apache.org<javascript:;> >>> >>> >>> --------------------------------------------------------------------- >>> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org >>> For additional commands, e-mail: dev-h...@commons.apache.org >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org >> For additional commands, e-mail: dev-h...@commons.apache.org >> > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > For additional commands, e-mail: dev-h...@commons.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
