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15.11. Editing Input

15.11.1. Problem

You want a user to be able to edit a line before sending it to you for reading.

15.11.2. Solution

Use the standard Term::ReadLine library along with the Term::ReadLine::Gnu module from CPAN:

use Term::ReadLine; $term = Term::ReadLine->new("APP DESCRIPTION"); $OUT = $term->OUT || *STDOUT; $term->addhistory($fake_line); $line = $term->readline($prompt); print $OUT "Any program output\n";

15.11.3. Discussion

The program in Example 15-4 acts as a crude shell. It reads a line and passes it to the shell to execute. The readline method reads a line from the terminal, with editing and history recall. It automatically adds the user's line to the history.

Example 15-4. vbsh

#!/usr/bin/perl -w # vbsh - very bad shell use strict; use Term::ReadLine; use POSIX qw(:sys_wait_h); my $term = Term::ReadLine->new("Simple Shell"); my $OUT = $term->OUT( ) || *STDOUT; my $cmd; while (defined ($cmd = $term->readline('$ ') )) { my @output = `$cmd`; my $exit_value = $? >> 8; my $signal_num = $? & 127; my $dumped_core = $? & 128; printf $OUT "Program terminated with status %d from signal %d%s\n", $exit_value, $signal_num, $dumped_core ? " (core dumped)" : "; print @output; $term->addhistory($cmd); }

If you want to seed the history with your own functions, use the addhistory method:

$term->addhistory($seed_line);

You can't seed with more than one line at a time. To remove a line from the history, use the remove_history method, which takes an index into the history list. 0 is the first (least recent) entry, 1 the second, and so on up to the most recent history lines.

$term->remove_history($line_number);

To get a list of history lines, use the GetHistory method, which returns a list of the lines:

@history = $term->GetHistory;

15.11.4. See Also

The documentation for the standard Term::ReadLine module and the Term::ReadLine::Gnu from CPAN


15.10. Reading Passwords		15.12. Managing the Screen