[PD-dev] [ pure-data-Patches-1543850 ] $@ and $# expansion (argc, argv)

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Patches item #1543850, was opened at 2006-08-21 03:24
Message generated for change (Comment added) made by eighthave
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Category: puredata
Group: wishlist
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: IOhannes m zmölnig (zmoelnig)
Assigned to: Miller Puckette (millerpuckette)
Summary: $@ and $# expansion (argc, argv)

Initial Comment:
the attached patch extends the $-expansion mechanism:

$# expands to the number of arguments; usable both as
A_DOLLAR (just "$#") and A_DOLLSYM ("$#-bla")

$@ expands to the entire list of arguments (e.g. [$@
$@( will expand [1 2 3( to [1 2 3 1 2 3(); this is only
usable as A_DOLLAR; i.e. [symbol $@-a( will always
expand to "$@-a"

why:
well, its a way to deal with dynamic length lists that
is still missing in pd (though 1st steps have been made
with [list])


caveats:
what is still missing is an expansion for the selector
of messages and objects (the selector of an object
would be the object's instantation name); would $$ be a
good name for this? (since $0 is already taken)

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>Comment By: Hans-Christoph Steiner (eighthave)
Date: 2012-10-11 09:01

Message:
This is included in Pd-extended 0.43

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Comment By: Mathieu Bouchard (matju)
Date: 2007-01-12 21:24

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i think that $@ is what is necessary to allow abstractions to do what they
want with args, and that $# is not so useful in comparison, and what would
be more useful than $# (in the sense of avoiding more detours) would be to
be able to do a $@-like thing that only starts at the Nth argument, e.g. if
I have an abstraction that takes $1 $2 $3 and then a variable number of
arguments, and those arguments starting with $4 are to be all written
directly in an objectbox. witness the strange stuff going on in [nqpoly]...

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Comment By: IOhannes m zmölnig (zmoelnig)
Date: 2007-01-02 10:52

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updated for current CVSversion of pd (2007-01-02)
File Added: dollargcargv.patch

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Comment By: Hans-Christoph Steiner (eighthave)
Date: 2006-08-22 15:21

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Yes!  This is great!

As for the selector, $0 is not taken in message space, so I
think it makes sense there.  Since message expansion
variables are already different than object arguments, I
think that won't be too confusing.  Plus the $ variable
syntax comes from shell scripting, where $0 is basically the
selector of the message that is the command line arguments.

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