Project idea: a poor man's VC backend

Project idea: a poor man's VC backend

[Marcin Borkowski]

In a recent question on ESE
(http://emacs.stackexchange.com/questions/2849/save-current-file-with-a-slightly-different-name)
the topic of versioning by means of putting a timestamp into the
filename came up again (it does have its place, especially when
communicating with people unable to learn a real VCS).

Just wondering: would it be possible/easy/reasonable to provide
something like this within the Emacs VC framework?

Best,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University

Re: Project idea: a poor man's VC backend

[Stefan Monnier]

> Just wondering: would it be possible/easy/reasonable to provide
> something like this within the Emacs VC framework?

Yes.


        Stefan

Re: Project idea: a poor man's VC backend

[Eli Zaretskii]

> From: Marcin Borkowski <mbork@wmi.amu.edu.pl>
> Date: Thu, 11 Dec 2014 17:09:05 +0100
> 
> In a recent question on ESE
> (http://emacs.stackexchange.com/questions/2849/save-current-file-with-a-slightly-different-name)
> the topic of versioning by means of putting a timestamp into the
> filename came up again (it does have its place, especially when
> communicating with people unable to learn a real VCS).
> 
> Just wondering: would it be possible/easy/reasonable to provide
> something like this within the Emacs VC framework?

Are you talking about time-stamp.el?

Re: Project idea: a poor man's VC backend

[Marcin Borkowski]

On 2014-12-11, at 18:59, Eli Zaretskii wrote:

>> From: Marcin Borkowski <mbork@wmi.amu.edu.pl>
>> Date: Thu, 11 Dec 2014 17:09:05 +0100
>> 
>> In a recent question on ESE
>> (http://emacs.stackexchange.com/questions/2849/save-current-file-with-a-slightly-different-name)
>> the topic of versioning by means of putting a timestamp into the
>> filename came up again (it does have its place, especially when
>> communicating with people unable to learn a real VCS).
>> 
>> Just wondering: would it be possible/easy/reasonable to provide
>> something like this within the Emacs VC framework?
>
> Are you talking about time-stamp.el?

Not really.

I mean that e.g. C-x v v will "do the right thing", for instance:

I'm editing file.el (the only file in the current directory).  I press
C-x v v.  I'm asked for a "commit message" and the current contents of
file.el are save as e.g. file.el.2014-12-11-20:39:01-CET or something
like that, with the "commit message" put at the beginning in a comment
(for example).  I edit it further, and C-x v v behaves similarly.  Then,
I can press C-x v =, and see the diff between the current version and
the last stamped one.  Or C-u C-x v = and be asked (with autocompletion)
for the timestamp.  Then, have similar commands for analogs of
blame/annotate, revert to earlier versions etc.

Of course, it's impossible to recreate the functionality of Git in this
way.  Or even RCS, I'm afraid.  But for many use cases this might be
enough (for instance, one/two authors working on a single LaTeX file of
the paper).  (One paticular functionality that would be difficult to
implement would be branching; while possible, it might be even
misleading and hence dangerous.  Remember, the target would be the
users, uhm, not wise enough to use a real VCS;-).)

The rationale would be that e.g. if I work with a non-computer-savvy
researcher, any "real" VCS might be confusing; I might be expected to
e.g. send him file versions with a timestamp in the filename etc.

Best,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University

Re: Project idea: a poor man's VC backend

[Marcin Borkowski]

On 2014-12-11, at 17:38, Stefan Monnier wrote:

>> Just wondering: would it be possible/easy/reasonable to provide
>> something like this within the Emacs VC framework?
>
> Yes.

You mean yes/yes/yes or some other combination?  I might be tempted to
try to implement this, but my time and Elisp-fu are limited.

>         Stefan

Best,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University

Re: Project idea: a poor man's VC backend

[Stefan Monnier]

>>> Just wondering: would it be possible/easy/reasonable to provide
>>> something like this within the Emacs VC framework?
> You mean yes/yes/yes or some other combination?  I might be tempted to
> try to implement this, but my time and Elisp-fu are limited.

I haven't tried, but AFAICT it should be yes/yes/yes.


        Stefan

Re: Project idea: a poor man's VC backend

[Marcin Borkowski]

On 2014-12-11, at 21:17, Stefan Monnier wrote:

>>>> Just wondering: would it be possible/easy/reasonable to provide
>>>> something like this within the Emacs VC framework?
>> You mean yes/yes/yes or some other combination?  I might be tempted to
>> try to implement this, but my time and Elisp-fu are limited.
>
> I haven't tried, but AFAICT it should be yes/yes/yes.

Great.  So when I have some spare time, I'll try to look into this.

>         Stefan

Best,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University

Re: Project idea: a poor man's VC backend

[Rainer M Krug]

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Marcin Borkowski <mbork@wmi.amu.edu.pl> writes:

> On 2014-12-11, at 18:59, Eli Zaretskii wrote:
>
>>> From: Marcin Borkowski <mbork@wmi.amu.edu.pl>
>>> Date: Thu, 11 Dec 2014 17:09:05 +0100
>>> 
>>> In a recent question on ESE
>>> (http://emacs.stackexchange.com/questions/2849/save-current-file-with-a-slightly-different-name)
>>> the topic of versioning by means of putting a timestamp into the
>>> filename came up again (it does have its place, especially when
>>> communicating with people unable to learn a real VCS).
>>> 
>>> Just wondering: would it be possible/easy/reasonable to provide
>>> something like this within the Emacs VC framework?
>>
>> Are you talking about time-stamp.el?
>
> Not really.
>
> I mean that e.g. C-x v v will "do the right thing", for instance:
>
> I'm editing file.el (the only file in the current directory).  I press
> C-x v v.  I'm asked for a "commit message" and the current contents of
> file.el are save as e.g. file.el.2014-12-11-20:39:01-CET or something
> like that, with the "commit message" put at the beginning in a comment
> (for example).  I edit it further, and C-x v v behaves similarly.  Then,
> I can press C-x v =, and see the diff between the current version and
> the last stamped one.  Or C-u C-x v = and be asked (with autocompletion)
> for the timestamp.  Then, have similar commands for analogs of
> blame/annotate, revert to earlier versions etc.
>
> Of course, it's impossible to recreate the functionality of Git in this
> way.  Or even RCS, I'm afraid.  But for many use cases this might be
> enough (for instance, one/two authors working on a single LaTeX file of
> the paper).  (One paticular functionality that would be difficult to
> implement would be branching; while possible, it might be even
> misleading and hence dangerous.  Remember, the target would be the
> users, uhm, not wise enough to use a real VCS;-).)
>
> The rationale would be that e.g. if I work with a non-computer-savvy
> researcher, any "real" VCS might be confusing; I might be expected to
> e.g. send him file versions with a timestamp in the filename etc.

As it seems you are really aware of the pitfalls and dangers of using
this approach, I would suggest to not look into creating a
"time-stamp-file-based" VCS, but rather use on your side e.g. git, and
write some batch files which will be create time-stamped versions based
on git and also add a new time-stamped (time of check in) file to git. In this way, you
will have a good working VCS (git) with all the advantages, but also the
possibility to create consistent time-stamped files and check in new
time-stamped files.

Cheers,

Rainer


>
> Best,

-- 
Rainer M. Krug
email: Rainer<at>krugs<dot>de
PGP: 0x0F52F982

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Re: Project idea: a poor man's VC backend

[Marcin Borkowski]

On 2014-12-12, at 09:11, Rainer M Krug <Rainer@krugs.de> wrote:

> Marcin Borkowski <mbork@wmi.amu.edu.pl> writes:
>
>> On 2014-12-11, at 18:59, Eli Zaretskii wrote:
>>
>>>> From: Marcin Borkowski <mbork@wmi.amu.edu.pl>
>>>> Date: Thu, 11 Dec 2014 17:09:05 +0100
>>>> 
>>>> In a recent question on ESE
>>>> (http://emacs.stackexchange.com/questions/2849/save-current-file-with-a-slightly-different-name)
>>>> the topic of versioning by means of putting a timestamp into the
>>>> filename came up again (it does have its place, especially when
>>>> communicating with people unable to learn a real VCS).
>>>> 
>>>> Just wondering: would it be possible/easy/reasonable to provide
>>>> something like this within the Emacs VC framework?
>>>
>>> Are you talking about time-stamp.el?
>>
>> Not really.
>>
>> I mean that e.g. C-x v v will "do the right thing", for instance:
>>
>> I'm editing file.el (the only file in the current directory).  I press
>> C-x v v.  I'm asked for a "commit message" and the current contents of
>> file.el are save as e.g. file.el.2014-12-11-20:39:01-CET or something
>> like that, with the "commit message" put at the beginning in a comment
>> (for example).  I edit it further, and C-x v v behaves similarly.  Then,
>> I can press C-x v =, and see the diff between the current version and
>> the last stamped one.  Or C-u C-x v = and be asked (with autocompletion)
>> for the timestamp.  Then, have similar commands for analogs of
>> blame/annotate, revert to earlier versions etc.
>>
>> Of course, it's impossible to recreate the functionality of Git in this
>> way.  Or even RCS, I'm afraid.  But for many use cases this might be
>> enough (for instance, one/two authors working on a single LaTeX file of
>> the paper).  (One paticular functionality that would be difficult to
>> implement would be branching; while possible, it might be even
>> misleading and hence dangerous.  Remember, the target would be the
>> users, uhm, not wise enough to use a real VCS;-).)
>>
>> The rationale would be that e.g. if I work with a non-computer-savvy
>> researcher, any "real" VCS might be confusing; I might be expected to
>> e.g. send him file versions with a timestamp in the filename etc.
>
> As it seems you are really aware of the pitfalls and dangers of using
> this approach, I would suggest to not look into creating a
> "time-stamp-file-based" VCS, but rather use on your side e.g. git, and
> write some batch files which will be create time-stamped versions based
> on git and also add a new time-stamped (time of check in) file to git. In this way, you
> will have a good working VCS (git) with all the advantages, but also the
> possibility to create consistent time-stamped files and check in new
> time-stamped files.

Let me necromance this thread.

Thanks for this suggestion; it is a very good one.  However, what
I *really* would like to do is learning how Emacs' VC works.

Now I have another problem.  I decided to start reading the code for VC,
and after seeing the lisp/vc directory with its 41 files, felt a bit
overwhelmed.  Any suggestions on where to start reading to actually
understand anything?

> Cheers,
>
> Rainer

Regards,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University

Re: Project idea: a poor man's VC backend

[Dmitry Gutov]

On 01/15/2015 12:41 AM, Marcin Borkowski wrote:

> Now I have another problem.  I decided to start reading the code for VC,
> and after seeing the lisp/vc directory with its 41 files, felt a bit
> overwhelmed.  Any suggestions on where to start reading to actually
> understand anything?

You should start with the header commentary in lisp/vc/vc.el, and you 
can pretty much skip all VC backends you're not interested in.

RE: Project idea: a poor man's VC backend

[Doug Lewan]

> -----Original Message-----
> From: help-gnu-emacs-bounces+dougl
> To: help-gnu-emacs@gnu.org
> Subject: Re: Project idea: a poor man's VC backend
> 
> Thanks for this suggestion; it is a very good one.  However, what
> I *really* would like to do is learning how Emacs' VC works.

Excellent! That is a major part of the GNU philosophy.
Emphasize it!
I once had the task of designing a debugger and GDB was
the only thing around to learn from.

> 
> Now I have another problem.  I decided to start reading the code for
> VC,
> and after seeing the lisp/vc directory with its 41 files, felt a bit
> overwhelmed.  Any suggestions on where to start reading to actually
> understand anything?

First, look at the names of all those files and understand
which ones you shouldn't care about at the beginning.
(All those ediff files, for example, probably don't offer the big picture.)

Next I'd recommend that you look inside vc.el.
The commentary in the top matter alone gives good hints
about the history and design.
A significant part of this is to understand
that VC never calls a function for a specific version control system directly.
Instead, it figures out what the VC system is and then
picks the right set of functions and variables to use and then
assign them to a common set of variables.
(This is a common lisp technique and well worth learning
if you don't already know it.)

To delve into the code proper I might look 
at the help for C-x C-v C-v (M-x vc-next-action).
It's a vague concept, essentially "do the right thing".
Figure out how it decides what the next action should be.
Then study that action to see what variables (see above) it uses.
Those are your hooks into adding to the mode.

I hope this helps.

-- 
,Doug
Douglas Lewan
Shubert Ticketing
(201) 489-8600 ext 224 or ext 4335

"This is a slow pup," he said continuing his ascent.

Re: Project idea: a poor man's VC backend

[Damien Wyart]

* Marcin Borkowski <mbork@wmi.amu.edu.pl> in gnu.emacs.help:
> The rationale would be that e.g. if I work with a non-computer-savvy
> researcher, any "real" VCS might be confusing; I might be expected to
> e.g. send him file versions with a timestamp in the filename etc.

You might want to have a look at this:
http://www.catb.org/esr/src/

The interface is really simple, and vc-src.el has already been added in
Emacs (devel).

-- 
DW

Re: Project idea: a poor man's VC backend

[Joost Kremers]

Damien Wyart wrote:
> * Marcin Borkowski <mbork@wmi.amu.edu.pl> in gnu.emacs.help:
>> The rationale would be that e.g. if I work with a non-computer-savvy
>> researcher, any "real" VCS might be confusing; I might be expected to
>> e.g. send him file versions with a timestamp in the filename etc.
>
> You might want to have a look at this:
> http://www.catb.org/esr/src/

SRC. Great name for a revision control system ... Lowest googleability
ever. ;-)



-- 
Joost Kremers                                   joostkremers@fastmail.fm
Selbst in die Unterwelt dringt durch Spalten Licht
EN:SiS(9)

Re: Project idea: a poor man's VC backend

[Marcin Borkowski]

On 2015-01-15, at 21:17, Joost Kremers <joost.m.kremers@gmail.com> wrote:

> Damien Wyart wrote:
>> * Marcin Borkowski <mbork@wmi.amu.edu.pl> in gnu.emacs.help:
>>> The rationale would be that e.g. if I work with a non-computer-savvy
>>> researcher, any "real" VCS might be confusing; I might be expected to
>>> e.g. send him file versions with a timestamp in the filename etc.
>>
>> You might want to have a look at this:
>> http://www.catb.org/esr/src/
>
> SRC. Great name for a revision control system ... Lowest googleability
> ever. ;-)

Take that, LaTeX.

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University

Re: Project idea: a poor man's VC backend

[Bob Proulx]

Joost Kremers wrote:
> Damien Wyart wrote:
> > * Marcin Borkowski <mbork@wmi.amu.edu.pl> in gnu.emacs.help:
> >> The rationale would be that e.g. if I work with a non-computer-savvy
> >> researcher, any "real" VCS might be confusing; I might be expected to
> >> e.g. send him file versions with a timestamp in the filename etc.
> >
> > You might want to have a look at this:
> > http://www.catb.org/esr/src/
> 
> SRC. Great name for a revision control system ... Lowest googleability
> ever. ;-)

I know what you mean.  I immediately think of the "links" web browser.

  http://links.twibright.com/

Bob