[Tutor] Is this possible and should it be done?

[wolfrage8765 at gmail.com]

On Mon, May 21, 2012 at 4:06 PM, William R. Wing (Bill Wing)
<wrw at mac.com> wrote:
> On May 21, 2012, at 6:38 AM, wolfrage8765 at gmail.com wrote:
>
>> All, I have had a curious idea for awhile, and was wondering the best
>> way to implement it in Python and if it is even possible. The concept
>> is this, a file that is actually a folder that contains multiple files
>> (Like an Archive format). The actual files are really un-important.
>> What I want is for the folder to be represented as a single file by
>> any normal file browser, but to be able to access the files with-in
>> via Python. I will actually use the word archive to represent my
>> mystical folder as a file concept for the rest of this message. Some
>> additional things I would like to be possible: is for multiple copies
>> of the program to write to the same archive, but different files
>> with-in at the same time (Reading & Writing to the archive should not
>> lock the archive as long as they are different files); and for just
>> the desired files with-in the archive to be loaded to memory with out
>> having to hold the entire archive in memory.
>> Use case for these additional capabilities. I was reading about how
>> some advanced word processing programs (MS Word) actually save
>> multiple working copies of the file with-in a single file
>> representation and then just prior to combining the working copies it
>> locks the original file and saves the working changes. That is what I
>> would like to do. I want the single file because it is easy for a user
>> to grasp that they need to copy a single file or that they are working
>> on a single file, but it is not so easy for them to grasp the multiple
>> file concepts.
>
> As others have noted, this smells a lot like a .tar or similar archive.
>
> I'd suggest that it also smells like a scaled down and locally served Concurrent Versioning System.  CVS does exactly what you want in terms of preserving only differences between edited versions of a file and it only locks the particular file that has been checked out; also allows you to back up to any previous version of a file.  There are CVS-Python bindings (as well as SVN-Python, SVN being a newer more modern version of CVS).  Google will turn up lots of references to both.
>
> -Bill

Hey that sounds really interesting I did not know that SVN or CVS was
even an option, but can they work with an archive, I will have to
experiment, but that would take care of the multiple working copies
and final merges latter. Thanks for the idea!