On Wed, May 22, 2002 at 11:11:13PM +0100, [EMAIL PROTECTED]
wrote:
> Scot. Is $a guaranteed to be untouched?
Perhaps some context would help (and possibly present alternative
solutions, though these have been really fun).
Imagine something like this:
## $a is a flag that indicates we should do something
$SIG{HUP} = sub { $a++ };
while( 1 ) {
foo();
...
bar();
...
## check to see if we need to reread config file
if( data_is_stale() || $a ) {
$a = 0;
reread_config_file();
do_something_else();
do_yet_something_else();
}
## now $a is 0 and the above code won't get invoked again until
## someone sends us a HUP
}
For simplicity's sake, I reduced the problem to what Alistair quoted
above:
if( $a ) {
$a = 0;
do_something();
do_something_else();
...
}
Hence my original question: can the 'if( $a ) { $a = 0; ... }'
construct be done in fewer characters than my best try:
if( $a%2 .. $a-- ) {
do_something();
...
}
My example assumes the following constraints: $a is zero (or any even
number) to begin with. This next example doesn't assume digits, but it
does require the starting value of $a to be the empty string:
$SIG{HUP} = sub { $a='foo' };
$a = '';
while( 1 ) {
yada_yada();
if( $a=~s/.*// ) {
do_something();
...
}
}
I don't care what constraints you impose, as long as the block gets
executed exactly once and only when $a is true (for whatever you want
to define as true).
Shortest (looking) answer yet (which several people posted) is:
$a && $a-- && do {
do_something();
...
}
Two questions: a) can it be shortened to fewer characters? and b) is
there another way to do it better in general?
This has been a fun thread, btw (for me, anyway). Thanks.
Scott
--
Scott Wiersdorf
[EMAIL PROTECTED]
