[PD-dev] some tclpd questions/comments

[Hans-Christoph Steiner]

On Nov 7, 2011, at 5:43 PM, mescalinum at gmail.com wrote:

> Il 07/11/2011 23:25, Hans-Christoph Steiner ha scritto:
>> I'm just trying my hand at writing my first tclpd library, 'tclfile', which is basically all of the individual subcommands of Tcl's 'file' command broken out as separate objects.
> 
> cheers!
> 
>>  This has given rise to a couple questions/comments:
>> 
>> - do I need to use proc+ or can I just use proc?
> 
> proc+ is defined in tclpd.tcl as follows:
> 
>    proc proc+ {name arglist body} {
>        set body2 [concat "global _;" [regsub -all @(\\\$?\[\\w\\?\]+) $body _(\$self:\\1)]]
>        uplevel #0 [list proc $name $arglist $body2]
>    }
> 
> it allows you to have per instance ($self) object variables, like you usually have fields in the t_yourobject struct when coding externals in C (always have the first method argument called 'self'!)



>> - it seems like the 'constructor' proc is the same as Pd's setup() function.  If so, I think it should also be called 'setup'.
> 
> it is not the setup function.
> maybe it is the _new() function

Ah right, yes, outlet creation is done in _new mostly.  It would be nice to have tclpd use the same function names as Pd as much as possible because then the Pd docs like the Externals HOWTO will then also apply to Tclpd.   free() is another name instead of destructor.

>> - is there an 0_anything/A_GIMME proc that can be used?
> 
> yes
> check examples/dynreceive.tcl
> 
>> 
>> - multi-level namespaces to represent library and classname?  Something like tclfile/mkdir would be tclfile::mkdir and have tclfile::mkdir::constructor.
> 
> didn't think of that, and right now it is not possible (the calling mechanism is hardcoded in c as ::<classname>::method)

I can imagine that for an full library written with tclpd, there would be shared code between the objects.  That would then be in the ::tclfile namespace.  Then each object would have a sub-namespace, i.e. ::tclfile::mkdir  This will also make name collisions easier to avoid.  There could be multiple libs with objects called 'mkdir'.  I was thinking, the pd::class proc could just take the final piece of the namespaces as the object name

I have another question: with proc+ 0_symbol I seem to get "\{symbol blah\}" as $args.  That's really hard to work with, how about making 0_symbol $args just be the symbol itself, i.e. "blah". This is what I had to do to get it to work:

    set @filename [lindex {*}$args 1]

Also, I couldn't figure out how to output a float to the outlet, my attempt creates a message that is "float 1" but not a float:

    pd::outlet $self 0 [list float [file exists $@filename]]

Here's my start of a 'tclfile' lib:
http://pure-data.svn.sourceforge.net/viewvc/pure-data/trunk/externals/tclfile/

.hc

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