Thank you very much for the correction.
However, after checking your Wiki references, I must say I still donīt
understand the difference between context and containment (these are
words that I naively used as synonyms in my message).
In <http://www.zope.org/Wikis/zope-dev/AcquisitionUsage> we find:
- Containment: Search the object, then its container, then the
container's container, and so on. Ignore objects not in this chain.
- Context: Search the objects in precisely the reverse of the order in
which they were mentioned, so "A.B.C.D" is always searched in the order
"D", "C", "B", "A".
But for me, A.B.C.D means that A contains B; B contains C; and C
contains D, so I donīt see the difference from the first definition.
Maybe you are using the word "container" in a more restricted sense?
Stephen Harrison wrote:
> Luciano Ramalho wrote:
> > [EMAIL PROTECTED] wrote:
> > > The effect I would like to achieve is:
> > > when user access http://myserver/,
> > > content of /text_object_1 and /text_object_2 will be shown
> > > while user access http://myserver/subfolder/,
> > > content of /subfolder/text_object_1 and /subfolder/text_object_2
> > >
> > > The point is that there's no index_html in /subfolder
> > > so /index_html will be acquested and by default it displays
> > > content of /text_object_1 and /text_object_2
> > >
> > > The question is: we got text_object_1 and text_object_2 in /subfolder
> > > how could I let the acquested index_html in subfolder to use the
> > > objects inside the subfolder?
> > What you want is what Zope already does!
> > That is how acquisition works: if /subfolder has no index_html, it will
> > acquire that object from the root. But the DTML inside index_html will
> > be rendered in the context (namespace) of the subfolder, so the desired
> > effect will be achieved.
> Unfortunately it is not quite as simple as that. Infact, to say that
> that is how acquisition works is misleading. It is not how acquisition
> works, but if you are using DTML Methods then you can create the effect
> of that being the way it works.
> Let me explain. When you acquire an object, the acquisition method used
> is to first look at the containment of the object before the context of
> the object. So if you have the scenario described above, when you call
> /subfolder/ it fist looks for index_html inside subfolder, but it isn't
> there, so it looks in subfolders containing object, /, where it does
> find index_html. Now it executes index_html and finds a call to
> text_object_1. So it first looks inside index_html for text_object_1,
> but it can't find it, so it looks in the _containing_ object of
> index_html, /, and finds text_object_1.
> However, if index_html is a DTML Method then things are different,
> because a DTML Method does not have it's own namespace and isn't an
> object in it's own right - rather it is a method of the calling object.
> The problem with this *containment before context* is that in most cases
> it goes against what is trying to be achieved. In the example above,
> there may be very good reasons why index_html needs to be a document
> rather than a method - maybe it needs it's own properties, etc. The
> point is that most often, the important thing when calling an object is
> the *context* in which it is called, not the location in the object
> store where it happens to be located.
> As I have mentioned several times now on the list, I can't see any good
> reason why acquisition should use the containment before context method
> (refered to as Simplified Acquisition) and in my opinion it should be
> changed to use context before containment (refered to as Natural
> See http://www.zope.org/Wikis/zope-dev/AcquisitionUsage for some
> explanation of the different types of acquisiton, and
> http://www.zope.org/Wikis/zope-dev/AcquisitionFeedback for a summary of
> the problem as I see it - if you have opinions then do add them.
> Also, Patrick Lewis wrote:
> > Try changing /index_html as follows:
> > <dtml-var standard_html_header>
> > <table>
> > <tr><td><dtml-var "PARENTS.text_object_1" fmt=structured-text>
> > </td></tr>
> > <tr><td><dtml-var "PARENTS.text_object_2" fmt=structured-text>
> > </td></tr>
> > </table>
> > <dtml-var standard_html_footer>
> > Basically force Zope to look in the current folder first.
> That is all well and good for solving this particular problem, but it
> crosses a threshold in terms of accessability to the person writing the
> code. For a 'non-programmer', writing <dtml-var object> is not too
> difficult or scary, but <dtml-var "PARENTS.object"> is a world apart
> and quite a scary place to be. It's complicated, it doesn't make a lot
> of sense and it makes doing what should be quite simple things
> I work with a variety of people here, some of whom have no problem at
> all with any of the above, but others for whom there is a definite
> barrier between the first and second snippets of code. It's like the
> old "function(_, _.None) thing, which just shouldn't be necessary, but
> that's a different story.
> Anyway, in this particular case, if acquisition worked in a more useful
> way (see above) then this problem would be avoided.
> Stephen Harrison [EMAIL PROTECTED]
> New Information Paradigms www.nipltd.com
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