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chainTo: and chainUnlinkLast

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keith1y

chainTo: and chainUnlinkLast

Dear Lukas,

your rewrite of MAChainAccessor provoked some panic here!

Just to let you know that I had written a couple of chaining and
unchaining operaterations, which I use for mapping a flat db query into
a magritte model. It allows me to treat a chain accessor as a kind of
stack as the model is traversed.

These are

#last
#chainTo:
#chainUnlinkLast:

I thought that you might be interested in adopting these (now they are
fixed for the latest) as utilities into MA-Model. If you are interested
then you will find them in the latest Magritte-RDB package in magritte
addons.

best regards

Keith

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Lukas Renggli-2

Re: chainTo: and chainUnlinkLast

Hi Keith,

> your rewrite of MAChainAccessor provoked some panic here!

sorry, I didn't expect that anybody was using those.

I think with the refactoring they became more useful, especially since
you don't need to know anymore about the details. You can now just write

aDescription accessor: #foo

and it will automatically create the appropriate accessor object for
you. The same for

aDescription accessor: #(foo bar)

will chain #foo to #bar.

> Just to let you know that I had written a couple of chaining and
> unchaining operaterations, which I use for mapping a flat db query
> into a magritte model. It allows me to treat a chain accessor as a
> kind of stack as the model is traversed.

I don't know if that is useful in general? If you think so, please
feel free to add it to Magritte-Core. I saw that you use it to build a
stack. Wouldn't it be much simpler if you just kept the selectors in
an OrderedCollection and sent #asAccessor if required?

Cheers,
Lukas

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

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keith1y

Re: chainTo: and chainUnlinkLast

Lukas Renggli wrote:

> Hi Keith,
>
>
>> your rewrite of MAChainAccessor provoked some panic here!
>>
>
> sorry, I didn't expect that anybody was using those.
>
> I think with the refactoring they became more useful, especially since
> you don't need to know anymore about the details. You can now just write
>
> aDescription accessor: #foo
>
> and it will automatically create the appropriate accessor object for
> you. The same for
>
> aDescription accessor: #(foo bar)
>
> will chain #foo to #bar.
>
>
>> Just to let you know that I had written a couple of chaining and
>> unchaining operaterations, which I use for mapping a flat db query
>> into a magritte model. It allows me to treat a chain accessor as a
>> kind of stack as the model is traversed.
>>
>
> I don't know if that is useful in general? If you think so, please
> feel free to add it to Magritte-Core. I saw that you use it to build a
> stack. Wouldn't it be much simpler if you just kept the selectors in
> an OrderedCollection and sent #asAccessor if required?
>

I have to say that this is a very bumpy migration! I have over 900
existing instances and the new implementation is reversing the instVars.
At present I am attempting to reverse them by hand but it is tricky.

Keith

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