重新建立初始状态的安全方法

Question

是否有可能调用函数main而不调用函数_end_win ?

#!/usr/bin/env perl
use warnings;
use strict;
use 5.10.0;
use Term::ReadKey;
use constant {
    NEXT_getch      => -1,
    CONTROL_C       => 0x03,
    CONTROL_D       => 0x04,
    KEY_ENTER       => 0x0d,
    KEY_RIGHT       => 0x1b5b43,
    KEY_LEFT        => 0x1b5b44,
};

say main();
sub main {
    my $arg = {};
    $arg->{handle_out} = *STDOUT;
    _init_scr( $arg );
    while ( 1 ) {
        my $c = _getch( $arg );
        if ( ! defined $c ) {
            _end_win( $arg );
            warn "EOT";
            return;
        }
        next if $c == NEXT_getch;
        given ( $c ) {
            when ( $c >= 97 && $c <= 122 ) {
                print chr $c;
                $arg->{string} .= chr $c;
            }
            when ( $c == KEY_RIGHT ) {
                print '>';
                $arg->{string} .= '>';
            }
            when ( $c == KEY_LEFT ) {
                print '<';
                $arg->{string} .= '<';
            }
            when ( $c == CONTROL_D ) {
                _end_win( $arg );
                return;
            }
            when ( $c == CONTROL_C ) {
                _end_win( $arg );
                print STDERR "^C";
                kill( 'INT', $$ );
                return;
            }
            when ( $c == KEY_ENTER ) {
                _end_win( $arg );
                return $arg->{string};
            }
        }
    }
}
sub _init_scr {
    my ( $arg ) = @_;
    $arg->{old_handle} = select( $arg->{handle_out} );
    $arg->{backup_flush} = $|;
    $| = 1;
    Term::ReadKey::ReadMode 'ultra-raw';
}
sub _end_win {
    my ( $arg ) = @_;
    print "nr";
    Term::ReadKey::ReadMode 'restore';
    $| = $arg->{backup_flush};
    select( $arg->{old_handle} );
}
sub _getch {
    my ( $arg ) = @_;
    my $c1 = ReadKey 0;
    return if ! defined $c1;
    if ( $c1 eq "e" ) {
        my $c2 = ReadKey 0.10;
        if ( ! defined $c2 ) { return NEXT_getch; }
        elsif ( $c2 eq 'C' ) { return KEY_RIGHT; }
        elsif ( $c2 eq 'D' ) { return KEY_LEFT; }
        elsif ( $c2 eq '[' ) {
            my $c3 = ReadKey 0;
            if ( $c3 eq 'C' ) { return KEY_RIGHT; }
            elsif ( $c3 eq 'D' ) { return KEY_LEFT; }
            else {
                return NEXT_getch;
            }
        }
        else {
            return NEXT_getch;
        }
    }
    else {
        return ord $c1;
    }
}

Answer 1

为确保程序退出时终端复位，将复位代码放入END块中。例如，可以将_end_win子节点替换为:

END {
    print "nr";
    Term::ReadKey::ReadMode 'restore';
}

(我删除了重置$|和select输出文件句柄的行，因为进程无论如何都要退出，所以它们将变得无关紧要。)

当程序以"正常"方式终止时，例如调用exit或die或到达可执行代码的末尾时，END块将始终运行。当进程因接收到信号而终止时，它不会触发;它看起来像你直接处理ctrl-C字符，但你可能要考虑添加一个%SIG{INT}处理程序，以防有人发送给你一个kill -2。