Hmm.
Factories have always seemed most useful to me when they are
encapsulating the creation of some configurable resource. In practice,
it seems like "configurable" most often means pulling a string from some
attribute or properties file, and using that to choose implementation.
If the type of Archiver I am using is static and would never change, I
would simply the Archiver's constructor. If it's not static and will
change, you are almost always going to have to deal with a string at
some point. Passing that string into a factory is easier than getting
this ZIP member via reflection (and cleaner than special casing every
Archiver type)
--Will
Sandy McArthur wrote:
On 5/12/06, Torsten Curdt <[EMAIL PROTECTED]> wrote:
> here is a new draft:
> http://www.grobmeier.de/commons-compress-draft-6.zip
>
> I have changed a lot of things discussed with draft 5.
> The API is easier now. Everything what seems to be unnecessary has
been
> deleted. Compress is working with Files and InputStreams only, no more
> String-params are allowed. New is also ArchiveEntry, which represents
> the entry of an archive ;-).
>
> For example, a zip file can be created like this:
>
> Archiver archiver = ArchiverFactory.ZIP.getInstance();
Why not use a proper factory? Did you consider my suggestions?
http://www.mail-archive.com/commons-dev@jakarta.apache.org/msg79370.html
At Draft 3 or 4 I suggested he use a type safe enum for an
"ArchiveType" which fully implemented would have implicitly had the
factory feature built in and can remain extendable. eg:
ArchiveType someType = ArchiveType.valueOf("zip")
Archive someArchive = someType.newInstance();
the small problem with that or any factory is the use of a String to
request a behavior means the compiler cannot know for sure if that
code will work. The enum solves this if the programmer wants by having
the constants. If the compiler allows the following you know it work:
Archive zip = ArchiveType.ZIP.newInstance();
That said, it's better to commit to one idiom. Chris, as long as you
have the ball on this you gotta pick the suggestions that work well
together from all the feedback. On the surface the "ArchiveFactory"
Factory/Enum hybrid seems to be less good than just using either a
factory pattern or an enum pattern alone.
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
