co-processes

Jonathan has asked for the wisdom of the Perl Monks concerning the following question:

I am currently rewriting my Korn shell scripts in perl (who said an old dog can't learn new tricks) and would like to know the best way to re-write ksh co-process handling.
For example how could the following example be best re-written?

# Open co-process
co_process_program |&
while read -p output
do
    if ((input_required == true))
    then
        input="just do some work";
        print -p $input;
    fi

    if [[ $output = +(*done*) ]]
    then
        input="do something else";
        print -p $input;
    fi

    if [[ $output = +(*finished*) ]]
    then
        input="time to go";
        print -p $input;
        break;
    fi
done
[download]

Comment on co-processes Download Code

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Re: co-processes by ZZamboni (Curate) on May 05, 2000 at 20:32 UTC
I'm not sure what you mean by "co-process handling". It seems to me that you are executing a command and reading its output. Is that it? In that case, one way of doing it with perl would be: `open(CMD, "co_process_program \|") or die "Error: $!\n"; while(<CMD>) { # each line of input will be in $_ } close(CMD);` [download]	[reply] [d/l]
RE: co-processes by Jonathan (Curate) on May 07, 2000 at 06:32 UTC
No, theres a lot more to it than that. The example was a very stripped down version. Perhaps a better one is to consider an interactive SQL program. Your script wants to run some sql, get back the number of rows processed and then decide whether the transaction should be commited or rollbacked. (Note this is only an example - anyone who mentions DBI will be shot ;-)	[reply]