Johan Corveleyn wrote on Tue, Dec 13, 2011 at 22:04:33 +0100: > On Tue, Dec 13, 2011 at 8:16 PM, Daniel Shahaf <d...@daniel.shahaf.name> > wrote: > > C. Michael Pilato wrote on Tue, Dec 13, 2011 at 14:01:45 -0500: > >> On 12/13/2011 01:25 PM, Eric S. Raymond wrote: > >> > C. Michael Pilato <cmpil...@collab.net>: > >> >>> Does a file replace differ in any way from a delete plus add of the > >> >>> new text? > >> >> > >> >> In Subversion, yes. A replacement is, like an add or a delete, an > >> >> operation > >> >> at the node level, not an operation on the contents of that node. A > >> >> replace > >> >> is an addition of a new object[1] -- with its own new line of version > >> >> control history -- that is coincidental with the removal of some > >> >> previously > >> >> existing object that occupied the same path. > >> > > >> > I still don't understand how this differs from a delete followed by an > >> > add. > >> > Explain it to me like I'm reallllyyy stuuupid, please, so I can document > >> > it > >> > and you never have to explain it again. > >> > > >> > When I add a file at a given path, it creates new object with a > >> > history that is tracked. When I delete that path, I destroy the > >> > container as well as the content. If I subsequently create a new > >> > file at the same path, it's a new object with its own history. > >> > > >> > How is a replace different? > >> > >> Assume your "delete" and subsequent "add" happens in the same commit, it's > >> not different at all. In fact, the Subversion filesystem API doesn't even > >> recognize a "replace" operation. There's "delete (file or dir)", there's > >> "make file" and "make dir", and there's "copy (file or dir)". The > >> "replace" > >> action found in the dumpfile is just a compacting of some delete operation > >> and a subsequent add or copy into a single verb, and that only because it > >> helps sequential processors of the dump stream avoid possibly notifying > >> about multiple actions on the same path. We favor the likes of: > >> > >> R /some/file.txt > >> > >> over: > >> > >> D /some/file.txt > >> A /some/file.txt > >> > >> in output. > >> > >> (My prior response was the result of my misreading your phrase "delete plus > >> add of the new text" as meaning "removing all the contents of the file, and > >> then adding all new contents of the same file". I see now that you were > >> talking about "container" operations, not content ones. Sorry about that.) > >> > >> >> [1] Most of the time. A replacement can have a copyfrom source, in > >> >> which > >> >> case its not strictly a new line of history for that object. > >> > > >> > I think I get this part. When you replace with a copy source, you're > >> > destroying the container that existed at this path, abd replacing it with > >> > a new container that has history extending back through the copy source. > >> > Is that correct? > >> > >> Yup! > >> > >> I was trying to think through the generalities here, too. I believe they > >> boil down to this: > >> > >> "delete" stands alone. It never has text. Never has properties. > >> Never has copyfrom. > >> > >> "add" and "replace" can have text if the added object is a file. The > >> text is the contents of the added object as it appears in the committed > >> revision. "add" and "replace" of directories can not have text. > >> > >> "add and replace" can have properties -- the set of properties present > >> on the added file/directory in the committed revision. > >> > >> "add and replace" can have copyfrom information, indicating that the > >> "added" object does not truly represent the creation of a new line of > >> history, but is instead a continuation of a pre-existing line of > >> history. This is still an addition of sorts in that the object is newly > >> added to the set of its parent directory's list of children. > >> > >> But I haven't double-thunk that for complete accuracy. > >> > >> > So, everything except a delete can include properties and they all > >> > work the same way. Correct? > >> > >> Yes. > >> > >> >>> If a file replace can have a copyfrom source, how does replace with a > >> >>> copyfrom source differ from add with a copyfrom source? > >> >> > >> >> The differ only in the fact that a replace implies the simultaneous > >> >> deletion > >> >> of some other object which previously lived at that path. > >> > > >> > Got it. That case I understand, it's how they differ in the non-copyfrom > >> > case that still confuses me. > >> > >> This is replace without copyfrom: > >> > >> $ svn rm some/file.txt > >> $ touch some/file.txt > >> $ svn add some/file.txt > >> $ svn ci -m "Replace some/file.txt with a new file." > >> > >> This is replace with copyfrom: > >> > >> $ svn rm some/file.txt > >> $ touch some/file.txt > >> $ svn copy someother/differentfile.txt some/file.txt > >> $ svn ci -m "Replace some/file.txt with a copy of a different file ." > > > > And: > > > > $ svn rm some/file.txt > > $ touch some/file.txt > > $ svn copy some/file.txt@HEAD some/file.txt > > $ svn ci -m "Replace some/file.txt with a copy itself." > > And even: > > $ svn mv some/file.txt some/otherfile.txt > $ svn mv some/otherfile.txt some/file.txt > $ svn ci -m "Replace some/file.txt with a copy of itself." > > (pre-1.7 this would be a replace without copyfrom, breaking the line > of history [1], but that is fixed as of 1.7) >
But the fix is client-side, right? One can still do things like that by driving an RA commit editor directly. > [1] http://subversion.tigris.org/issues/show_bug.cgi?id=3429 - "svn mv > A B; svn mv B A" generates replace without history > > -- > Johan
