[PD-dev] mystery type generated by [list trim]

Hans-Christoph Steiner hans at eds.org
Sun Oct 29 01:29:34 CEST 2006

On Oct 28, 2006, at 3:57 AM, Frank Barknecht wrote:

> Hallo,
> Hans-Christoph Steiner hat gesagt: // Hans-Christoph Steiner wrote:
>> A student just discovered this strange behavior.  Basically, if you
>> get something that generates a symbolic atom that has numeric data in
>> it, you can then create a mystery type by feeding that thru [list
>> trim].  Don't know exactly where the problem is, but something fishy
>> is going on.
> What "list trim" does on a "symbol X" is generate a meta message
> consisting only of the selector "X". But here this selector is
> numeric. Numeric selectors are illegal, because selectors have to be a
> symbol. It could be considered a bug in the patch trying to generate
> such illegal meta-messages. Removing the [list trim] will fix the
> patch as will adding a [list] after [list trim].
>> My guess is that [list trim] should output a float.
> To me it is a bug in the patch rather than in [list trim]. In my
> understanding [list trim] is designed to remove the "list"-selector
> and through that the other two standard Pd selectors, "float" and
> "symbol" as well, but it was not designed to add them or to convert
> from "symbol ..." to "float ...". For that, [list] itself should be
> used.

Yes, this is a strange thing to do, but I am just illustrating a  
point.  This problem came to my attention because of a real world  
problem where OSC from Flash is being received from Pd fine, but its  
generating this format of data, and it is therefore useless (without  
[atoi], which works correctly here, IMHO).

If this is a totally useless and illegal value, then nothing should  
ever generate it.  By definition, anything that can be interrupted as  
a number, should be a float.  The Pd manual 2.1.2 says "Anything that  
is not a valid number is considered a symbol" ("symbol" here meaning  
symbolic atom, not symbol message).  That means that the converse  
should be true too: "anything that is a valid number should be  
considered a float".

Therefore any atom containing "1234" should always be a float.



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