Hi Krzysztof,
The "reenter" flag is supposed to protect against recursion; if a qlist gets a recursive "rewind", "next", etc message, the reenter flag should stop the qlist from bashing its state afterward. It seems I haven't got it right yet however...! I don't have time to get into Pd sources right now (teaching and concerts!) but will try to get this one right in a 34.x release soon.
I hadn't realized pointers could be put in qlists. I think that's dangerous and don't know what to do about it. It certainly doesn't make sense to save a pointer to a file...
cheers Miller
On Wed, Sep 26, 2001 at 06:01:11PM +0200, Krzysztof Czaja wrote:
hi,
after proposing midifile<->qlist addition I thought I would check the recently changed qlist version.
First of all, it still gives an error while running
... <target> next; <delay> <target> ...
sequence, if <target>'s output is connected to qlist's input. I am now looking at the code, and suspect that the added x_reentered flag-field is meant to break infinite loops, occuring when a qlist object is self-feeding itself with a 'rewind' message.
Well, reading code is misleading most of the time, so I may be wrong, but if not, then it is rather a `restarted' flag.
So my question is this: what about recursive `next' message? Can we simply say, that it should not be used? Maybe so, but maybe there is even simpler solution. What happens now is that:
- qlist_donext() in passes 1 to n of its main loop reads all
not delayed messages up to a recursive `next';
- recursive `next' causes invocation of a child-call of
qlist_donext();
- a child-call reads remaining messages up to a float (delay)
and quits;
- in pass n+1 of the main loop of parent-call, qlist_donext()
reuses a previous target, passing it a new target as a message selector -- error.
Target reusing should happen iff a new message is preceded by a comma -- or am I completely wrong here? If I am right, then maybe instead of checking, if we are going to read a new target, ie. instead of using a
semicolon-flag', it would be better to use acomma-flag', ie. to check, if we are going to use a previous target.This change would protect from semicolon-swallowing recursion.
Btw. what is the policy about adding pointers to qlists? It is now possible, but 1) pointer values cannot be saved in a file, and 2) in the current implementation pointers act as `comments', ie. everything starting from the pointer and up to a comma or a semicolon is ignored.
Krzysztof