[PD] [list] output

Jonathan Wilkes jancsika at yahoo.com
Sat Feb 6 05:18:34 CET 2010

--- On Fri, 2/5/10, Matteo Sisti Sette <matteosistisette at gmail.com> wrote:

> From: Matteo Sisti Sette <matteosistisette at gmail.com>
> Subject: Re: [PD] [list] output
> To: "PD list" <pd-list at iem.at>
> Date: Friday, February 5, 2010, 7:56 PM
> Hi,
> Maybe I'm late, but I try to answer to the questions that
> have been raised about the list stuff, for two reasons:
> first, in case this is helpful to those who asked, and
> second, so that those who know more than I do can correct me
> where I'm wrong or show me if the whole thig can be stated
> in a different way.
> This is my understanding of how lists and messages
> interact.
> 1) The "float" or "list" identifiers are implicit when a
> message starts with a number atom, so
>  [1( is equivalent to [float 1(
>  [1 2 3( is equivalent to [list 1 2 3(
> Another way of stating this (perhaps more correct??) may be
> that a message cannot start with a number atom, i.e. it
> always starts with a symbol atom which is its identifier, so
> if you type "1" into a message box (or a text file read by
> [textfile]) the message actually generated has an implicit
> (or automatically added) "float" or "list" identifier -
> Which of the two interpretations is more correct is, from my
> point of view, just an implementation matter.
> 2) One-element lists are equivalent to symbols or numbers,
> depending on the type of their only element, so
>   [list foo( is equivalent to [symbol foo(
>   [list 1( is equivalent to [float 1( - which is
> equivalent to [1(
> 3) Equivalent means that ALL objects in Pd will treat such
> messages exactly the same way. The fact that some signal
> objects such as
>   [*~]
> will not accept "list <somenumber>" complaining they
> have no method for list, is in my opinion a BUG. Somebody
> just forgot to do the needed conversions at the inlets. I
> remember someone agreed with me on this.
> Whether the conversions are made at outlets or inlets of
> objects is another implementation matter that I think should
> be transparent/irrelevant to the user.

It is a bug.

I'm concerned mainly with documentation, and for an object like [list], 
I think it's best to say that it always outputs messages with the "list" 
selector, but also say how the message "list" and one-element lists are 
handled by objects in Pd.  (The paragraph in [pd list trim] in 
list-help.pd already goes in this direction, it just needs to be expanded.)



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