26 Jan
2004
26 Jan
'04
10:40 a.m.
On Tue, Jan 27, 2004 at 12:59:30 +1100, rd(a)alphalink.com.au wrote:
Good :))
Well actually it is only doing the byte encoding. SC3, being dragged out
for yet another example, allows users to link in the synthesis engine and
push OSC packets directly onto a queue, thus avoiding any IPC
operations but still using an identical communication protocol. For the
liblo case you are of course correct, but the temporal behaviour of the
encoder/decoder can be pretty predictable.
Yes, true.
Did you get that the wrong way round? I though to problem was that 1.0 was
an integer in scheme? Couldnt the problem be solved by specifying the type
explicitly at send time and doing the coercion then? eg:
(-> "/foo" "isf" 100 "hello" 100.0)
- Steve
OK,
interesting - it wouldn't be a huge task, but why is this a good
idea?
It just seems inconvienient for the recipient and
I dont know of any
other
RPC mechanisms where its allowed (or wanted). In
the case of
typetag-less
messages it would be difficult to handle,
you'd have to try to discover
the type of the argument by inspection. Do you have a link to a
rationale
for this?
Firstly, from the horses mouth, "non-type-tagged messages [are] totally
deprecated". See
<http://www.create.ucsb.edu/pipermail/osc_dev/2003-November/00032
9.html> and surrounding posts. I don't think you need to even try to think
about possibly considering perhaps partially supporting such things! Secondly, it is actually no work for the receiver.
The receiver says that is
needs a signed 32bit integer and it gets such an integer. It is a little
work for the library. On the other hand it can be a lot of work for the
sender. Domain specific languages often do not implement full C like
numerical towers, a signal processing language could easily only
implement floating point numbers, Lua famously has only double
precision floating point numbers, and lots of people use Lua.
Thats only true if thier using the engine to do the type conversion for
them, if thier doing it by hand then its going to need a lot of switch
(cond?) statements.
Since I think this is really important I will give an
example, and from the
other end of a continuum. I use scheme for most of my music work.
Scheme has a very sophisticated numerical tower. I might write (->
"/n_set" 1001 "freq" 440) to set the frequency of an instrument at
SC3.
The OSC encoder encodes values based on their lisp type, 1001 is an
integer and gets encoded as 'i'. Lets assume that to the receiver the
frequency argument is a float, here I lose because 440 is an integer. I
argue that a receiver implemented like that is just wrong, that an integer
440 frequency is completely valid, and SC3 thankfully agrees and plays
the right note.
However if you disagree and say that I should write the literal as a float
then that makes scheme a hopeless language to work in, 440.0 is still
an exact integer, I need to write #i440 to get an inexact integer. But the
situation is far worse, if I write (* m 1.5) this seems like it should make
an inexact value regardless where m arrives from, however scheme
knows that (* 0 1.5) is an exact zero and I lose again, it may even know
that (* 2 1.5) == (* 2 3/2) == 3, an exact integer . Forcing a user to _very_
carefully annotate _all_ code that might get sent as an OSC packet
_only because_ the OSC receiver cannot accept exact integers is not
going to work, I just won't be able to work with the process. SC3 gets
this very right, as usual, and in fact allows:
OK, I see your problem, but its just further convinced me that scheme is
not a nice language ;) [I never liked lisp].
How far do you want to take the conversion? Do strings get converted to
float? Timestamps? Perl could easily get confused and send 1.0 as "1.0" or
vice versa if you weren't careful.
* not allocate any memory or call any other non-RT
safe procedure
This one is inherantly not possible, youre doing i/o operations.
I've
always been more of a strongly-typed guy :)
Me too, we schemers all are, we just think that an exact integer is a real
number :)