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Posted to dev@commons.apache.org by Timothy James Pinet <tp...@zenasus.com> on 2008/10/05 16:05:59 UTC
COMPRESS-REDESIGN: What is the purpose of the reflection usage in ArchiveStreamFactory and CompressorStreamFactory?
Good morning,
Out of curiosity why must reflection be used for the create*Stream() methods in the ArchiveStreamFactory and CompressorStreamFactory? There is a cast at the end of each method to a corresponding interface anyway (ex ArchiveInputStream, ArchiveOutputStream, etc) so why cant we use this knowledge ahead of time and execute on the interface? The current implementation makes it next to impossible to capture errors being thrown by the constructors of new implementations since the reflective methods discard any Exceptions and simply return null.
I would like to know why this design decision was made just in case I am missing something.
Regards,
Tim
Re: [compress] What is the purpose of the reflection usage in ArchiveStreamFactory and CompressorStreamFactory?
Posted by Torsten Curdt <tc...@apache.org>.
Applied! (Only modified slightly) Thanks!
On Wed, Jan 7, 2009 at 07:31, Christian Grobmeier <gr...@gmail.com> wrote:
> Hi,
> sorry for beeing late :-)
>
>> I guess we could also just get rid of the reflection. What do you think?
>
> I think this is good. I have attached a patch to:
> https://issues.apache.org/jira/browse/SANDBOX-262
> which eliminates the reflection usage in both factories.
>
> Can sombody (Torsten? :-)) please review the patch and apply it, if it is ok?
>
> Thanks,
> Christian
>
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Re: [compress] What is the purpose of the reflection usage in ArchiveStreamFactory and CompressorStreamFactory?
Posted by Christian Grobmeier <gr...@gmail.com>.
Hi,
sorry for beeing late :-)
> I guess we could also just get rid of the reflection. What do you think?
I think this is good. I have attached a patch to:
https://issues.apache.org/jira/browse/SANDBOX-262
which eliminates the reflection usage in both factories.
Can sombody (Torsten? :-)) please review the patch and apply it, if it is ok?
Thanks,
Christian
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Re: [compress] What is the purpose of the reflection usage in ArchiveStreamFactory and CompressorStreamFactory?
Posted by Torsten Curdt <tc...@vafer.org>.
> I will fix it up and suggest a patch to bring it to a workable state.
I guess we could also just get rid of the reflection. What do you think?
cheers
--
Torsten
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Re: [compress] What is the purpose of the reflection usage in ArchiveStreamFactory and CompressorStreamFactory?
Posted by Timothy James Pinet <tp...@zenasus.com>.
Reflection does handle checked exceptions for Constructor.newInstance() and
this is handled appropriately for:
public ArchiveInputStream createArchiveInputStream( final String
archiverName, final InputStream out ) throws ArchiveException {...}
However, the other method:
public ArchiveInputStream createArchiveInputStream( final InputStream
input ) throws IOException {...}
is not implemented to handle checked constructor exceptions since all
Exception catches are not handled. It looks as though this method was not
completed. I will fix it up and suggest a patch to bring it to a workable
state.
Thanks,
Tim
--------------------------------------------------
From: "Torsten Curdt" <tc...@apache.org>
Sent: Sunday, October 05, 2008 10:27 AM
To: "Commons Developers List" <de...@commons.apache.org>
Subject: [compress] What is the purpose of the reflection usage in
ArchiveStreamFactory and CompressorStreamFactory?
> Hey there
>
>> Out of curiosity why must reflection be used for the create*Stream()
>> methods in the ArchiveStreamFactory and CompressorStreamFactory? There
>> is a cast at the end of each method to a corresponding interface anyway
>> (ex ArchiveInputStream, ArchiveOutputStream, etc) so why cant we use
>> this knowledge ahead of time and execute on the interface?
>
> I think the idea that it makes "dropping in" a new implementation easier.
> But I agree with you.
>
> As the registerArchive*Stream methods need to be called to register the
> implementation this becomes a moo point.
>
> I would change the factory to
>
> public ArchiveInputStream createArchiveInputStream( final String
> archiverName, final InputStream stream ) throws ArchiveException {
>
> if ("ar".equals(archiverName)) {
> return new ArAchiveInputStream(stream)
> }
>
> ..
>
> return null;
> }
>
> and then instead of registering a new implementation you just extend the
> factory and overload the create*Stream methods to add your custom impl
> ...and of course delegate to the super class.
>
>> The current implementation makes it next to impossible to capture errors
>> being thrown by the constructors of new implementations since the
>> reflective methods discard any Exceptions and simply return null.
>
> Hm ... I thought that would be indeed possible:
>
> http://java.sun.com/docs/books/tutorial/reflect/member/ctorTrouble.html
>
> cheers
> --
> Torsten
>
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[compress] What is the purpose of the reflection usage in ArchiveStreamFactory and CompressorStreamFactory?
Posted by Torsten Curdt <tc...@apache.org>.
Hey there
> Out of curiosity why must reflection be used for the create*Stream()
> methods in the ArchiveStreamFactory and CompressorStreamFactory?
> There is a cast at the end of each method to a corresponding
> interface anyway (ex ArchiveInputStream, ArchiveOutputStream, etc)
> so why cant we use this knowledge ahead of time and execute on the
> interface?
I think the idea that it makes "dropping in" a new implementation
easier. But I agree with you.
As the registerArchive*Stream methods need to be called to register
the implementation this becomes a moo point.
I would change the factory to
public ArchiveInputStream createArchiveInputStream( final String
archiverName, final InputStream stream ) throws ArchiveException {
if ("ar".equals(archiverName)) {
return new ArAchiveInputStream(stream)
}
..
return null;
}
and then instead of registering a new implementation you just extend
the factory and overload the create*Stream methods to add your custom
impl ...and of course delegate to the super class.
> The current implementation makes it next to impossible to capture
> errors being thrown by the constructors of new implementations since
> the reflective methods discard any Exceptions and simply return null.
Hm ... I thought that would be indeed possible:
http://java.sun.com/docs/books/tutorial/reflect/member/ctorTrouble.html
cheers
--
Torsten
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