On Sun, Jan 10, 2010 at 12:53 AM, sebb <seb...@gmail.com> wrote: > On 09/01/2010, Niall Pemberton <niall.pember...@gmail.com> wrote: >> On Fri, Jan 8, 2010 at 1:37 PM, sebb <seb...@gmail.com> wrote: >> > On 08/01/2010, sebb <seb...@gmail.com> wrote: >> >> On 08/01/2010, Niall Pemberton <niall.pember...@gmail.com> wrote: >> >> > On Thu, Jan 7, 2010 at 9:51 PM, sebb <seb...@gmail.com> wrote: >> >> > > The overridable methods in DirectoryWalker currently use >> Collection<?> >> >> > > as a parameter type. >> >> > > >> >> > > As far as I can tell, the Collections need to contain File >> objects, so >> >> > > would it not be better to use Collection<File>? >> >> > > >> >> > > Might be nice to use Collection<? extends File>, but when I tried >> that >> >> > > there were some problems with the test cases. >> >> > > >> >> > > Any views? >> >> > >> >> > >> >> > DirectoryWalker doesn't actually control what gets put into the >> >> > collection - the user can put whatever they want. So someone could, >> >> > for example, use it to add String file names to the collection. If we >> >> > lock it down to File then that would break for them. >> >> >> >> >> >> OK, I see. Perhaps the Javadoc should make this more explicit. >> >> >> >> Also, there don't seem to be any unit tests apart from ones which use >> >> File entries. I'll try to add some. >> >> >> > >> > I'm having trouble removing the "raw type" warnings from the existing >> > test cases. >> > It's not clear how to write type-safe classes that override the >> > methods in DirectoryWalker. >> > >> > The override only works if one uses Collection<?> or Collection<? >> > extends Object> as the results parameter type, but then results.add() >> > generates a compiler error, as one cannot add anything to a collection >> > of <?>. >> >> >> Yes this is not good. >> >> >> > One can solve the problem by casting results to the appropriate type, >> > but that will be an unchecked cast. Every implementation will need to >> > include the casts, and it does not make any use of the type-checking >> > features of generics. >> > >> > The DirectoryWalker class probably needs to be genericised, so the >> > user can specify what Collection type to be used. >> > >> > Alternatively, maybe the results parameter could be specified as >> > Collection<Object>. >> > However, that will require lots of casts in user code, and does not >> > make best use of generics either. >> > >> > Any other solutions? >> >> >> I've added a generic type to DirectoryWalker: >> >> http://svn.apache.org/viewvc?view=revision&revision=897578 >> > > Great. > > I've added a String Collection test to the generics test case. > Shall I add it to the Java4 version?
I don't mind - up to you. Niall >> Niall >> >> >> >> >> > Niall >> >> > >> >> > --------------------------------------------------------------------- >> >> > 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
