4 Replies Latest reply on Jan 20, 2010 5:38 PM by alrubinger

    SHRINKWRAP-104: Empty Directories

    alrubinger
    alrubinger Dec 6, 2009 11:12 PM

      https://jira.jboss.org/jira/browse/SHRINKWRAP-104

      I've added support for empty directories (and tests) in r3836. This is nice, because importers can now account for empty dirs as well.

      The design I've used is a new Asset implementation:

      public enum DirectoryAsset implements Asset {

 /**
 * Singleton Instance
 */
 INSTANCE;

 /**
 * {@inheritDoc}
 * @see org.jboss.shrinkwrap.api.Asset#openStream()
 */
 @Override
 public InputStream openStream()
 {
 // To signify that we've got nothing to back us (we're just a directory),
 // we use null. A stream backed by an empty byte array would be an
 // empty file, which is different.
 return null;
 }

}


      This sucks because:

      1) We don't really obey the contract of "Asset", returning a null reference on "openStream"
      2) The implementation relies upon "instanceof" runtime type checking to do things like creating directories in the exporter. Meaning we're checking for a specific implementation.

      An alternate approach is to add: 

      Asset.isDirectory()


      ...to all Asset types. In this case "DirectoryAsset.openStream" would still return null, but we could do "Asset.isDirectory" instead of the runtime type checking.

      Which is uglier to you?

      S,
      ALR

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        • 1. Re: SHRINKWRAP-104: Empty Directories
          aslak
          aslak Dec 7, 2009 3:06 AM (in response to alrubinger)

          What if we drop the Asset all together and make a add method like:

          archive.add(Path)


          Maybe we then also have to support all the convenience overloads like ? 
          addManifestResource(Path)
addWebResource(Path)
etc..



          Path should then probably have a isDirectory method, checking if it ends with '/' seems to be common. Could add checks to other add methods so you can't add a Asset to a directory Path, can't get the Asset of a directory path etc..

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          • 2. Re: SHRINKWRAP-104: Empty Directories
            jesper.pedersen
            jesper.pedersen Dec 7, 2009 9:39 AM (in response to alrubinger)

            I say follow the java.io.File API and add

            isFile()
isDirectory()


            I'll let you worry about the implementation details ;)

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            • 3. Re: SHRINKWRAP-104: Empty Directories
              alrubinger
              alrubinger Dec 7, 2009 11:57 AM (in response to alrubinger)

               

              "aslak" wrote:
              What if we drop the Asset all together and make a add method like:
              archive.add(Path)


              @see DirectoryContainer, which has: 

              container.addDirectory(Path);
container.addDirectories(Path...);
container.addDirectory(String);
container.addDirectories(String...);


              All spec archives types bring in DirectoryContainer support.

              "aslak" wrote:
              Path should then probably have a isDirectory method, checking if it ends with '/' seems to be common. Could add checks to other add methods so you can't add a Asset to a directory Path, can't get the Asset of a directory path etc...


              Paths, as defined, don't know anything about what's under them in the context of an archive. So in my view a directory is more of an Asset; it's what's some Path in an archive.

              S,
              ALR



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              • 4. Re: SHRINKWRAP-104: Empty Directories
                alrubinger
                alrubinger Jan 20, 2010 5:38 PM (in response to jesper.pedersen)

                jesper.pedersen wrote:

                 

                I say follow the java.io.File API and add

                isFile()
isDirectory()


                I'll let you worry about the implementation details ;)

                The motivation behind ArchivePath was that it specifically did *not* follow this pattern, which IMO couples things.

                 

                On some further review, we can just say in the JavaDoc of Asset that "returning null on getInputStream() denotes a logical Path only with no content".  Then we follow the API.

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