--------
Phil Taylor writes:
| John Chambers wrote:
| >Possible, but it would require a bit of a change to current parsers.
| >Like most ABC programs, my code tries hard to ignore everything that
| >isn't part of an ABC "tune". And it's real hard to write code that
| >matches English-language warnings or restrictions. If they're in
| >other languages, it's even harder.
|
| I was thinking of more formal instructions which could be placed in
| a field in the abc, e.g.
|
| I:RobotsDontIndex
|
| or
|
| I:RobotsWholeFileOnly
|
| and which (ideally) might become part of the abc standard.
Putting such instructions inside the ABC "tunes" would certainly
help. But I'd question whether this would have the desired result.
In the case of my search bot, it does read the entire file. Its job,
after all, is to build an index of the ABC tunes that it finds. It
pretty much has to read the entire file. So the second I field
wouldn't change its behavior at all. The first would, but would just
mean that the file wouldn't be indexed. You can do this with the
robots.txt file, but this I field would be better for ABC if that's
what you want.
The extraction of single tunes is done by other programs, CGI scripts
in my Tune Finder's case. And even they still download the entire
file, because again that's all they can do. There's no way to ask a
web server for a portion of a file; you just have to read through it
from the beginning. You can disconnect after you've found what you
want, but you can't avoid reading everything before that. (And it's
likely that if you disconnect, the server will have sent the entire
file by the time it realizes that you're gone, since file transfer
times are comparable to the two round trips that it takes for TCP to
terminate a connection.)
The "extraction" part comes about because of a web front end to my
tune index files that know how to do this. In at least one case, I
can again say that there's no choice. One of the formats returned is
MIDI. This is done by feeding the selected tune to abc2midi, which is
the only program that I know of that can run on unix as a subprocess
to a CGI script, read ABC, and produce MIDI. One of its properties is
that it only translates the first tune in its input. So if you want
to hear the 17th tune in the file, you must precede abc2midi with a
filter that cuts out everything before the X:17 line.
It's not obvious to me how the above I lines would apply to this. The
first would just mean that the tune wouldn't be in the index at all.
The second would mean that all MIDI requests would get the first
tune, in which case you might as well not bother (unless that's the
tune that the user asked for).
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