[PD-dev] $0 in messages, was: multiple $arg-expansion

[Hans-Christoph Steiner]

On Jan 15, 2006, at 9:28 AM, Frank Barknecht wrote:

> Hallo,
> Frank Barknecht hat gesagt: // Frank Barknecht wrote:
>
>> What I would be interested in more is being able to use $0 and other
>> $x *literally*, for example to be able to dynamically create
>> objects which use $0 as argument like:
>>
>>   [obj 100 100 f $0(
>>   |
>>   [s pd-subpatch]
>>
>> to create a [f $0] in [pd subpatch] and not a [f 1001].
>
> Ah, scrap that: Using "$0" this way in messages is not good, as it
> would be too different from how "$1,..." are used. Of course it's not
> possible nor useful to create a [f $1] by using "obj 100 100 f $1"
> This stuff needs proper escaping.
>
> So what about this, which tries to keep a bit of backwards
> compatibility:
>
> * Object arguments change from $x to #x with x in 0(sic!),1,...,n
>
> * $x in objects are kept for a while for compatibility
>
> * Messages will get additional placeholders for canvas-properties,
>   that start with a #hash and directly correspond to the object
>   arguments from above. They will keep $-placeholders starting from
>   1(sic!) as in the past.
>
> * There will be no $0 anymore in the long run.

I personally don't like expanding Pd's syntax with the #, I think one  
of Pd's strength is minimal syntax.

$ args are expandable arguments, whether in objects or in messages.   
You can break down everything in Pd to those two basic categories:  
objects and messages.  When you want an expandable argument, then use a  
$ arg.  Since objects and messages are different things, it makes sense  
that $ args don't expand to the same thing within objects and messages.  
  That seems nicely logical and compact to me.  I think if people have  
trouble with that, they are likely not understanding the distinction  
between messages and objects rather than the $ args themselves.

But using the instance ID in messages would be a handy shortcut, so $$  
could be the instance ID for both objects and messages without breaking  
anything AFAIK.  It would make $ arg parsing perhaps more tricky, but I  
that code could be lifted from BSD's sh, for example, since its  
tried-n-true and released under a BSD license.

.hc

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