What does this mean?

I saw some references to it in another older thread from last year..

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Richard E. Flower wrote: It takes a copy of the original, then compares the model to the copy to
make sure that no one else has changed it in the mean time, before
applying the new one.

If your real memento copy is not a completely independent copy then it
may be modifying the model by accident. On commit it finds the model has
changed.

Keith


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On Thu, August 21, 2008 10:46 am, Keith Hodges wrote:
> It takes a copy of the original, then compares the model to the copy to
> make sure that no one else has changed it in the mean time, before
> applying the new one.
>
> If your real memento copy is not a completely independent copy then it
> may be modifying the model by accident. On commit it finds the model has
> changed.

How does it determine (I guess I can pilfer thru the code tonight) if the
model has changed?  It's not like C++ comparing pointers -- is it doing a
bit-wise compare of each field (In a general sense)...?

Hmm.. In this case the model should not have changed -- it was rendered
and then I pressed the 'save' button w/o any changes.. I guess I'll have to
dig into the bowels of the RealMemento code (assuming that's where the
compare is being done)..

BTW -- what's the difference between MARealMemento and
MARealCheckedMemento?  I'm currently using MARealCheckedMemento --
not sure if that matters or not.. I only used that version because the
default Magritte one was MACheckedMemento IIRC.

-- Rick


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Magritte probably things that there is a conflict because GLORP  
doesn't keep the identity of objects and you don't properly implement  
#= in all the involved objects.

If the DB handles commit conflicts for you, there is no need for  
Magritte to do these checks for you. I remember doing some special  
memento class for OmniBase that used the mechanisms of the OODB to  
check for conflicts and to mark the changed parts as dirty.

If you don't want to check for conflicts you can simply replace the  
method Object>>#mementoClass to return MACachedMemento.

Cheers,
Lukas

--
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http://www.lukas-renggli.ch


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On Thu, August 21, 2008 1:24 pm, Lukas Renggli wrote:
> If the DB handles commit conflicts for you, there is no need for
Magritte to do these checks for you. I remember doing some special
memento class for OmniBase that used the mechanisms of the OODB to check
for conflicts and to mark the changed parts as dirty.
>
> If you don't want to check for conflicts you can simply replace the
method Object>>#mementoClass to return MACachedMemento.

I guess I'd like to have Magritte figure out if I need to issue a
'commit' or a roll-back and go from there..

I guess I'd like to know what the difference is between the following
(perhaps a good FAQ entry?):

1) MACachedMemento
2) MARealMemento
3) MACheckedMemento
4) MARealCheckedMemento
5) MAStraitMemento

Also -- is there a good place to read up on the object comparison operators
such as #=, #<, #>?  I've got a single ST book (in pdf form -- Smalltalk
by example) and didn't find any references to #= when doing a search and
little talk on comparisons..

Thx!



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> I guess I'd like to know what the difference is between the following
> (perhaps a good FAQ entry?):

Check out the class comments ;-)

Cheers,
Lukas

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http://www.lukas-renggli.ch


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On Thu, August 21, 2008 2:24 pm, Lukas Renggli wrote:
>> I guess I'd like to know what the difference is between the following
>> (perhaps a good FAQ entry?):
>
> Check out the class comments ;-)

Sorry Lukas.. One of these days I need to figure out how to see the class
comments while working in Squeak.. I know how in VW but not Squeak.. Anyway,
I'll check them out either way.. Thx!


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Ok -- solved my problem.. I put an address object as part of my  
Descriptions
but they are effectively 'sub' objects and I suspect I actually had  
two separate
objects.. I need to follow what others where talking about in the  
"Using One Magritte
form for two model objects" thread.. Thx!

-- Rick


On Aug 21, 2008, at 5:43 PM, Rick Flower wrote:


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Richard E. Flower wrote: With the realMemento sub-objects probably need to use a StraitMemento,
so that there is only one whole data-structure used as a memento.

Keith


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Thanks Keith!

On Aug 22, 2008, at 1:32 AM, Keith Hodges wrote:


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