a reading/presentation prog

[stabu]

I want to build a prog to read and concurrently edit edit text files in perl. For the first stage, I just wanted to write up a script which will make the lines of a text file appear one after the other after a certain time interval. I reckon this is achieveable for my elementary perl knowledge.

I plan to:

• slurp the file lines as a scalar
• split according to sentences
• put into an array and then
• print the array elements out,
• waiting a certain time interval each time.

Sounds like something some one has done already? Is there a wait function in perl? Can I write over the the previously printed-out array elements?

Thanks in adv for advice.

[holli]

while ( <> )
{
  print;
  sleep(60);
}

[anonymized user 468275]

That is assuming sentences are defined by "\n". The input line separator can however be changed early in the program, e.g.:

$/ = '.';
$snoozeTime = 10;
while( <> ) {
    print $_;
    sleep $snoozeTime;
}

But if ':' is also needed as a sentence terminator, there are a number of solutions for extracting the ':'-terminated sentences from each '.' separated chunk, especially regular expressions and the built-in function split.

[ysth]

Can I write over the the previously printed-out array elements?

The easiest way is to turn off buffering and start each output with a carriage return character and end with sufficient trailing blanks:

$|=1; # flush output after each print
@outputs = qw/fred jim sheila barney/;
$maxlen = 6;
$delaysecs = 1;
for my $out (@outputs) {
   printf "\r%-${maxlen}s", $out;
   sleep($delaysecs);
}
print "\n";

If your sentences wrap onto the next line on the terminal, you'll have to do something more fancy.