[PD] array size (was Re: arraysize)

Miller Puckette msp at ucsd.edu
Wed Oct 3 02:33:45 CEST 2012 

Right, the two demands I'm trying to reconcile are keeping the name
hip~ (so that old patches remain comprehensible) and yet making hip~
work correctly -- it's a bug fix.  Seems to me one ought to be able to fix 
bugs without diving into library version confusion.

I think namespaces are very useful to expert programmers but are likely to
be confusing to many Pd users -- and its not that much of a necessity if
indeed c (in which Pd and linux are implemented) didn't need to have
them.

cheers
Miller

On Tue, Oct 02, 2012 at 08:24:19PM -0400, Hans-Christoph Steiner wrote:
> 
> If you think that's the preferrable approach, then shouldn't it be
> [newhip~]?  One thing libc did not do is break backwards compatibility
> of functions.  I think the libc example is a better approach than the
> -pre-0.44-hip flag or the aliasing to work around the existing versions
> of [pow].
> 
> My central point is that Pd should have a fully functioning namespace
> like modern languages do (C++, Obj-C, Java, Python, Ruby, Lua, Haskell,
> etc. etc.)  That's one lesson that we've learned from C.  Part of that
> is having a standard library that can be overridden.  Then if people
> want to have old versions of the standard library, they can easily be
> accomodated by adding the version number to the name of the library.
> 
> .hc
> 
> On 10/02/2012 07:02 PM, Miller Puckette wrote:
> > The libc way is just to have one libc and kludge your way through
> > compatibility problems.  For instance, seek() had to be replaced with lseek(),
> > gets and fgets were left with not-quite-the-same behavior, errno was
> > magically adapted to become a macro that grabbed a thread variable when
> > threads appeared, etc.  It's not pretty but way preferable to having
> > several versions of libc - what a nightmare that would have been.
> >
> > cheers
> > Miller
> >
> > On Tue, Oct 02, 2012 at 06:48:46PM -0400, Hans-Christoph Steiner wrote:
> >> Is the static variable you are talking about the "static t_class"
> >> declaration in the class C files?
> >>
> >> What's the libc way?
> >>
> >> The -pre-0.44-hip way would be easy to implement, but it has a number of
> >> problems:
> >>
> >> - there will be many flags like this, -pre-0.42-pow, etc. etc.
> >>
> >> - there will be no way to specify in the patch that it should use a
> >> specific version of hip~, pow~, etc.  That adds complexity to the patch
> >> setups since each patch will need an accompanying script for launching
> >> Pd properly and means Pd programmers have to learn non-Pd things like
> >> scripting to do this.
> >>
> >> .hc
> >>
> >> On 10/02/2012 06:39 PM, Miller Puckette wrote:
> >>> Actually I think my previous post was wrong - what I was unable to do was
> >>> get different sets of static variables for dlopen() - ing the _same file
> >>> twice_ -- which isn't what we're talking about here.
> >>>
> >>> But still, I think the libc way is much simpler and likely to be much more
> >>> robust.
> >>>
> >>> cheers
> >>> M
> >>>
> >>> On Tue, Oct 02, 2012 at 06:13:32PM -0400, Hans-Christoph Steiner wrote:
> >>>> Since Pd manually loads the libraries (.pd_linux), it can also manually
> >>>> map a given function address to the s_thing in the symbol table.  There
> >>>> is no need to load the symbols in a .pd_linux in the sense of a public
> >>>> shared library, and therefore no nameclashes.  Pd could get the address
> >>>> of the new() function using dlsym() and store that wherever.  This is
> >>>> already happening for the setup() function, so we can do the same thing
> >>>> to map the new() function to a symbol..
> >>>>
> >>>> So for example, pd could map the new() function to the fully qualified
> >>>> name in the symbol table, i.e "vanilla-0.42.5/hip~", then only in the
> >>>> canvas_local namespace would the symbol "hip~" be mapped to the new()
> >>>> function.
> >>>>
> >>>> .hc
> >>>>
> >>>> On 10/02/2012 05:09 PM, Miller Puckette wrote:
> >>>>> I'm not sure that any of the Windows, MaacOS, and linux dynamic loading
> >>>>> systems will support having multiple versions of a library loaded in the
> >>>>> same address space.  But here's a simpler way anyhow:  libraries such as
> >>>>> vanilla could maintain compatibility by querying the version number of
> >>>>> the patch at run time.
> >>>>>
> >>>>> In the case of hip~  I'm genuinely not sure whether the "correct" behavior
> >>>>> would then be to revert to the old behavior for all old patches or only on
> >>>>> request.  The confusing scenario I worry about is that you have a patch with 
> >>>>> an old hip~ object in it, save it from 0.44, and then have it switch to the
> >>>>> new behavior next time it's loaded.
> >>>>>
> >>>>> I think I have found ad hoc ways to fix the other problems without breaking 
> >>>>> old patches.
> >>>>>
> >>>>> cheers
> >>>>> Miller
> >>>>>
> >>>>>  n Tue, Oct 02, 2012 at 11:36:47AM -0400, Hans-Christoph Steiner wrote:
> >>>>>> I think having a compatibility version stamp in the patch is a good
> >>>>>> idea.  This ties in well with the experiments I've been doing with
> >>>>>> splitting out all of the objects from pd itself.  If all of the core
> >>>>>> objects are a standard library, then that means its easy to choose which
> >>>>>> version of the standard library that a patch is using.  In Pd-extended,
> >>>>>> this is called the 'vanilla' lib, and its been included in some form
> >>>>>> since 0.42.
> >>>>>>
> >>>>>> Then if a patch has a compatibility version stamp in it, Pd can
> >>>>>> automatically look to see if it has a copy of that version of the
> >>>>>> standard library, and load it.  Otherwise, it would load the version
> >>>>>> closest to that, and throw a warning, or optionally that could be
> >>>>>> considered an error.
> >>>>>>
> >>>>>> To make this work well, the key missing feature is the ability to change
> >>>>>> which loaded library an object name maps to in the canvas-local
> >>>>>> namespace.  Currently, once an object name is mapped to a loaded
> >>>>>> .pd_linux, that is a global association.  This is needed so that patches
> >>>>>> using different standard libs can be open at the same time.
> >>>>>>
> >>>>>> Then making the versioned standard libs would be pretty easy, mostly
> >>>>>> just bundling the right .c files into a lib.
> >>>>>>
> >>>>>> .hc
> >>>>>>
> >>>>>>
> >>>>>> On 10/02/2012 11:15 AM, Miller Puckette wrote:
> >>>>>>> This is in my long-range plan but hasn't yet risen to the level of "urgent".
> >>>>>>> However, this migth be a good moment to get started on this because several
> >>>>>>> other backward- and even forward-imcompatible needs are also rising to the
> >>>>>>> fore:
> >>>>>>>
> >>>>>>> 1. there's a bug in hip~ - its DC gain is slightly (and possibly considerably)
> >>>>>>> greater than 1.  "fixing" this will change the audio output of older patches,
> >>>>>>> usually much too slightly to matter, but there will have to b a "-pre-0.44-hip"
> >>>>>>> flag or something to allow strict back compatibility;
> >>>>>>>
> >>>>>>> 2. There's no place in the pre-0.43 file format to alow specifying individual
> >>>>>>> box widths and font sizes; I put an "f" (=format) message to the canvas
> >>>>>>> object in 0.43 so that in 0.44 I can make it set font size and box width and
> >>>>>>> perhaps leave an opening for other formatting info.
> >>>>>>>
> >>>>>>> 3. the upsampling inlet~ by default zero-pads its input.  This is incorrect as
> >>>>>>> its DC gain is less than one.  (Try using that as input to a phasor~ for
> >>>>>>> instance - bad surprise!)  I want to change the default so that it acts like
> >>>>>>> a sample-and-hold, which I believe is an option now.  To preserve back 
> >>>>>>> compatibility I'd keep all the "upsampling methods" in place but only change
> >>>>>>> default behavior for patches with a 0.44 or later version stamped on them.
> >>>>>>>
> >>>>>>> Each of these presents a different spin on the age-old issue of keeping
> >>>>>>> total back compatibility in place, even when the compatibility is to preserve
> >>>>>>> a big as in (1) and (3) - and arguably in the file searching too; I'm not sure
> >>>>>>> whether to regard that as a bug or just over-hasty design.
> >>>>>>>
> >>>>>>> cheers
> >>>>>>> Miller
> >>>>>>>
> >>>>>>>>       Here's a good sketch of the idea
> >>>>>>>>       (http://puredata.info/dev/PdSearchPath):
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>       Proposed Functionality
> >>>>>>>>
> >>>>>>>>    for path in paths do -- the core does this bit
> >>>>>>>>      for loader in loaders do
> >>>>>>>>        loader(path, library, object)
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>       Existing Functionality
> >>>>>>>>
> >>>>>>>>   for loader in loaders do
> >>>>>>>>     for path in paths do -- the loader does this bit
> >>>>>>>>       loader(path, library, object)
> >>>>>>>>
> >>>>>>>> .hc 
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> _______________________________________________
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> >>>>>> _______________________________________________
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>

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