[PD] object names with "."

IOhannes m zmölnig zmoelnig at iem.at
Tue Oct 17 20:41:14 CEST 2017

On 10/17/2017 07:44 PM, Jonathan Wilkes via Pd-list wrote:
>> and how come underline works just fine?
> Because Pd's loader mechanism searches for the symbol "${libname}_setup", 
> where "${libname}" is the name of the library being loaded.
> If you make sure that "${libname}" is drawn from the set of characters thatcan appear in a C function name, then users will be able to load your object 
> in all the ways that Pd provides (using declare, using an absolute path name, 
> etc.)
> If instead you use characters that cannot appear in a C function name, you 
> either limit the ways that users can load that library or require complicated 
> workarounds like hexloader in order to make the library generally loadable.

for what it is worth, hexloader is not *very* complicated.

what most people seem to forget is, that hexloader really consists of
two parts, solving two different problems:
- allowing file names that would otherwise be forbidden (by the
underlying filesystem)
- allowing setup functions names that would otherwise be forbidden (by
the C-standard)

the allowed characters in C functions are well defined, e.g. [1]
the allowed characters in filenames are filesystem dependent, but a good
overview can be found at [2].

both problems are somewhat similar, as they try to encode the forbidden
characters into something not forbidden.
they both use the same method: replacing the forbidden characters with a

now the good news is, that if your object name only falls into one
category, then you only need to deal with that part.

the part of the hexloader implementation that is built into Pd, only
tackles the 2nd problem (function names).
since C function names are much more restrictive than file names, this
usually covers most problems (though obviously not all).

so, if you want an external that contains characters allowed on the
filesystem but forbidden as (part of) a function name, you only need to
provide a hexloadable name for the setup function, and don't have to
worry about ugly filenames that nobody understands.

furthermore, you don't even need to remember the way those hexloadable
setup function name is to be constructed. simply compile your external
into "foo.bar.pd_linux", start Pd with "-verbose" and try to instantiate
Pd will fail to load the external (as it cannot find and call the setup
function), but will display the setup name it tried to find when setting
the log-level to "all".

>> What other easy options do I have besides "_"?
> Why do you want to avoid using an underscore?



[1] http://www.c4learn.com/c-programming/c-variable-nameing-rules/
[2] https://en.wikipedia.org/wiki/Filename#Reserved_characters_and_words

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