Re: [Pythoncad-developer] Undo functionality

[<ger...@gm...>]

I like this idea of revisions.

The user can do undo steps in the current revision but not touch anything  
in any older revision, older revisions are "read only"
We need to think very carefully about the implementation.

I will start to write the use cases for "undo", "redo" and "show revision".
I will send you the links to these pages so anyone can add remarks and  
additions.

After that we can create the additional fields for the database tables from  
the use cases.

Regards,
Gertwin



Op schreef Matteo Boscolo <mat...@bo...>:
> You are right Yagnesh,



> Even if we think of a pdm integration ... or erp .. this will help us

> too mutch.



> we can provide 3 additional column at the entity table:

> date*revision*state



> date :

> could have null or a date

> if null we can delete the entity

> if date have a value we can not delete (it's versionade)



> revision:

> a number that indicate the revision

> could be a str field in case the user use letter insted of nuber for

> revision



> starte:

> Indicate the state of the entity released/undo_mark/... all we whant

> in case the date field is not null the state is released





> what do you think ?



> Regards

> Matteo





> On Sun, 2010-02-07 at 08:04 +0530, Yagnesh Desai wrote:

> > Gertwin;

> >

> > I like the Idea. I think providing the facility of how drawing looked

> > on a particular date is helpful, if we are able to tag that

> > particular state of drawing as Major "Revision" then it would

> > be very helpful.

> >

> > All engineers use drawings as Rev 0, Rev 1, Rev 2 etc. All

> > the intermediate states are not that important.

> >

> > That is I can roll back to older "sensible" version and not

> > the draft version of it.

> >

> > - - - - - -

> > Best regards

> > Yagnesh Desai

> > Save a tree...please don't print this e-mail.

> >

> >

> > On Sat, Feb 6, 2010 at 11:51 PM, ger...@gm...> wrote:

> > > Hi All,

> > >

> > > I was thinking about implementing undo functionality in combination  
> with the

> > > database.

> > > I am not aware how this is solved in the current version but with a  
> database

> > > we can make the undo recording persistent (you can undo changes from a

> > > previous drawing session).

> > >

> > > The idea is not to modify entities in the database but mark the old  
> entity

> > > state as deleted and insert a new record for the modified entity  
> state.

> > > Then there are two records in the database, one is the previous state  
> and

> > > one is the the current state of the entity.

> > > Of course the entities that are marked as deleted (previous state)  
> are not

> > > drawn.

> > >

> > > When the user does undo the current state is marked as deleted and the

> > > previous state is marked as not deleted.

> > > A redo does this marking in the opposite direction.

> > >

> > > If we add a column "state" and a column "undo_mark" to our entity  
> table we

> > > can achieve this.

> > > The column "state" holds the delete (or not) state.

> > > The column "undo_mark" holds the value of the undo id.

> > > Because the user can modify many entities at once all those entities  
> get the

> > > same "undo_mark".

> > >

> > > This way the history of the drawing is kept in the database and the  
> user can

> > > undo and redo actions from previous sessions.

> > > If we also add a time stamp we even can provide functionality that  
> will show

> > > how the drawing looked at a certain date.

> > >

> > > I think this functionality can have some use and is something other  
> CAD

> > > programs does not always provide.

> > > Undo and redo are simple database queries that are easy to implement.

> > > We must keep the display list in sync with the state of the database  
> but I

> > > think this also it not difficult.

> > >

> > > We also need a function that compresses the drawing by removing the  
> history.

> > >

> > > If it needs clarification, let me know I will try to explain.

> > >

> > > Do you think it is useful?

> > >

> > > Regards,

> > > Gertwin

> > >  
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