Re: A few issues and suggestions

At 10:30 PM 11/4/2008 +0200, Sergey Schetinin wrote:
>I applied the suggested fix and it resolved the issue in the app as
>well, thanks!
>
>I see how it wouldn't work for AddOns though, so I guess it's better
>to avoid mixing Components and Addons, or at least only create them in
>top-level, non-undoable code and not inside rules.

Either that, or make the addition undoable, but that only works 
correctly in an unthreaded program.  (Of course, there are no 
guarantees *anything* works correctly in a threaded program.  And in 
any case the trellis only supports threading in theory, not practice: 
cells would need to have their manager attribute set to some sort of 
lock in order to be (somewhat) safe.)


>On Tue, Nov 4, 2008 at 22:14, Sergey Schetinin <[email protected]> wrote:
> > On Tue, Nov 4, 2008 at 16:36, Phillip J. Eby <pje-Wh6+Hckhi6HFNGf7iClzIwC/[email protected]> wrote:
> >> I don't see from this example why .c's initialization 
> *shouldn't* be undone,
> >> unless you're saying that the make() isn't also being undone...  in which
> >> case the test should be about that.
> >
> > You're right, but in the app it wasn't obvious that the problem is
> > with make, what was apparent is that some changes from __init__ don't
> > stick. So, I didn't know what the problem is exactly, until I figured
> > out the test case.
> >
> >> It seems to me that the real issue here is that CellAttribute and
> >> TodoProperty don't undo-log their addition of a cell to a Component's
> >> __cells__.  I didn't originally do this because then the Cells() 
> addon would
> >> need to support locking to be able to be threadsafe in the future.  But I
> >> suppose that bridge can be crossed later.
> >>
> >> Is there any other reason besides this inconsistency, that the component
> >> __init__ shouldn't be undone?
> >
> > No, I think this is it.
> >
> >> (Btw, the same problem occurs with cells in addons and services, and won't
> >> be fixed by undo-logging the cell creation.  It's a big open issue at the
> >> moment, since even avoiding an __init__ doesn't help.  In essence, undo
> >> logging and "write-until-read" consistency simply don't mix, and  Addons,
> >> services, and the Cells() map all run off the write-until-read model.)
> >>
> >> At 05:09 AM 11/4/2008 +0200, Sergey Schetinin wrote:
> >>>
> >>> Here's the test case:
> >>>
> >>> class C(Component):
> >>>    x = attr(0)
> >>>    def __init__(self):
> >>>        self.x = 10
> >>>        @on_undo
> >>>        def undo():
> >>>            print 'UNDO'
> >>>
> >>>
> >>> class TC(Component):
> >>>    c = make(C)
> >>>    x = attr(0)
> >>>    y = attr(0)
> >>>
> >>>    @maintain
> >>>    def test(self):
> >>>        if self.x:
> >>>            self.c
> >>>            self.y
> >>>
> >>>    @maintain
> >>>    def write(self):
> >>>        self.y = self.x
> >>>
> >>>
> >>> tc = TC()
> >>>
> >>> @atomically
> >>> def test():
> >>>    tc.x = 1
> >>>    tc.test
> >>>
> >>> print tc.c.x
> >>>
> >>> # prints UNDO \ 0
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> On Tue, Nov 4, 2008 at 04:51, Sergey Schetinin <[email protected]> wrote:
> >>> >> Thanks for your help identifying and fixing the 
> problems.  I've checked
> >>> >> in
> >>> >> fixes, as described here:
> >>> >>
> >>> >> http://svn.eby-sarna.com?rev=2595&view=rev
> >>> >
> >>> > Thanks a lot. However, I see that some problems, that I thought was
> >>> > related to my monkeypatching, didn't go away, what happens in effect
> >>> > is that changes done Component.__init__ get rolled back. I'm working
> >>> > on a test case for this, and I've noticed something I didn't think
> >>> > about before. In the following example __init__ reads data it
> >>> > shouldn't. This isn't a problem normally, but something to keep in
> >>> > mind when writing components' __init__
> >>> >
> >>> > class TC(Component):
> >>> >    y = attr(0)
> >>> >
> >>> >    def __init__(self):
> >>> >        print self.read # 0
> >>> >
> >>> >    @compute
> >>> >    def read(self):
> >>> >        return self.y
> >>> >
> >>> >    @maintain
> >>> >    def write(self):
> >>> >        self.y = 5
> >>> >
> >>>
> >>>
> >>>
> >>> --
> >>> Best Regards,
> >>> Sergey Schetinin
> >>>
> >>> http://s3bk.com/ -- S3 Backup
> >>> http://word-to-html.com/ -- Word to HTML Converter
> >>
> >>
> >
> >
> >
> > --
> > Best Regards,
> > Sergey Schetinin
> >
> > http://s3bk.com/ -- S3 Backup
> > http://word-to-html.com/ -- Word to HTML Converter
> >
>
>
>
>--
>Best Regards,
>Sergey Schetinin
>
>http://s3bk.com/ -- S3 Backup
>http://word-to-html.com/ -- Word to HTML Converter