[PD] canvas path

[Frank Barknecht]

Hi,

here's some more food for thought: How to deal with library abstractions that
load other objects whose name is set at runtime? This is actually pretty
common, for example in abstractions that decorate other abstraction with e.g.
polyphony, or when writing soundfile/score loading objects.

I attached a test case that illustrates various combinations one may meet in
this case.

Please start Pd in the directory "metaprog" and open:

01_loadhere.pd
02_loadhere-declare-mylib.pd
03_loadhere-declare-dot.pd

Ciao
-- 
Frank


On Mon, Oct 20, 2014 at 08:34:13AM -0700, Miller Puckette wrote:
> Hi all,
> 
> I think it might work simply to maintain a per-patch list of "externs" 
> currently loaded.  New patches would start out with an empty list, which would
> then get filled in by that patch's own search procedures.
> 
> There might be some complicated problems to resove about such searche within
> abstractions (indeed, there are already severe problems the way that is set
> up that I want to try to fix.)
> 
> cheers
> Miller
> 
> Oe Sun, Oct 19, 2014 at 11:21:15AM -0700, Jonathan Wilkes via Pd-list wrote:
> > Hi list,
> > Let me describe a typical way to use Pd:
> > 1) patch author makes a patch
> > 2)
> >  patch author abstracts out certain functions into Pd abstractions
> > 3) patch author makes a self-contained collection of these abstractions (and maybe some helper abstractions)
> > 4) patch author takes every _reasonable_ step to make their collection portable-- that is, to ensure that their abstractions and nested abstractions create correctly on any version of Pd and don't collide with anything in the standard library path.
> > 
> > Currently a patch author cannot achieve this.  Pure data forces them to care about what names pre-existing externals might have (which is probably why many externals make a common name prefix part of the name of each object).  The reason is that an abstraction's directory is not the first place to be searched for externals or abstractions to be loaded.  It is superceded by the searchpath set by [declare] for all of that abstraction's parent canvases.
> > 
> > If any of those parent canvases declare a path which
> >  has an external or abstraction by the same name as one of the helper abstractions, the object in that path will get created instead of the helper abstraction.  Furthermore, if any of those parent canvases declare a path that happens to have the same name as the subdirectory containing the helper abstraction, then "path/objectname" will override "subdirectory/helper".  This is even true if you use "./subdirectory/helper".
> > 
> > This means that if the patch author wants to grope toward portability they have to do this, too:
> > 5) read/search all the libnames and object names in pd-extended, and all the other widely used libs and objects scattered about the internet.  Then come up with a name that is human readable, but also unique enough to prevent collisions with anything else out there.
> > 
> > I think #5 is unreasonable, especially because creating a little zipped directory with abstractions (or even externals) is such a common way of
> >  making ostensibly portable libraries in Pd.  Essentially we're asking users to do their own name-mangling.
> > 
> > So why isn't an abstraction's directory the _first_ one to be searched by default in Pd?  I understand katja and Matt Barber's reasons for using [declare] to infect an entire running instance with different path priorities, but I think that's the exception rather than the rule.  Can we give abstraction directories precedence in the loading scheme, and maybe use a startup flag to trigger Pd's current behavior?
> > 
> > -Jonathan
> 
> > _______________________________________________
> > Pd-list at lists.iem.at mailing list
> > UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
> 
> 
> _______________________________________________
> Pd-list at lists.iem.at mailing list
> UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list

-- 
 Frank Barknecht                                     _ ______footils.org__
-------------- next part --------------
A non-text attachment was scrubbed...
Name: metaprog.tgz
Type: application/x-gtar
Size: 816 bytes
Desc: not available
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20141020/ef8574c7/attachment-0001.gtar>