[PD] array size (was Re: arraysize)

Ed Kelly morph_2016 at yahoo.co.uk
Thu Oct 4 05:56:16 CEST 2012 

I think you can't fix a bug in a core object and retain complete backwards compatibility in terms of the audio result of old patches, unless you implement a "pre-0.44 mode" or something. But why would you want to do that? Perhaps a method can be used to switch between the two modes in hip~, but that might introduce a small overhead.

I think the integrity of the objects in terms of what they should do is more important than total backwards compatibilty - old patches will still load, but they may not sound _exactly_ the same. Personally I'd like hip~ to do highpass filtering properly, and so my expectation when I invoke hip~ is that it will do exactly that. Having a patch that "works like this but I don't know why" is a bad thing. I'd be sure to find the tiny DC component a nuisance at some point.

Ed 


>For the hip~ problem, I'm fine with just fixing it in 0.44, leaving it
>as hip~, and being done with it.  I agree with Jonathan: the default
>behavior should be the non-buggy behavior.
>
>The issue I am addressing is the -pre-0.44-hip idea and other ideas for
>providing backwards compatibility.  Namespaces provide a nice, clean
>technique for doing this, on top of other advantages.  And if we
>implement them right, people will only need to know about them if then
>need to do advanced things like running a patch in 0.44 while using a
>0.42 compatibility mode.
>
>Most users are just going to see the [import] or [declare] statement in
>a patch.  I think that's proven to be a much more newbie-friendly way to
>load external libraries than command line flags, especially on Mac and
>Windows.
>
>Namespaces are part of general programming, and are essential unless you
>are willing to greatly limit the domain the language is used for.  I
>think we can implement namespaces that are simple and Pdish.  I think
>we're close.  Even C requires the use of a crufty form of namespaces. 
>Try writing a C program without a single #include.
>
>.hc
>
>On 10/02/2012 08:33 PM, Miller Puckette wrote:
>> 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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