view release on metacpan or  search on metacpan

README  view on Meta::CPAN

NAME

    AnyEvent::Open3::Simple - Interface to open3 under AnyEvent

VERSION

    version 0.90

SYNOPSIS

     use 5.010;
     use AnyEvent;
     use AnyEvent::Open3::Simple;
     
     my $done = AnyEvent->condvar;
     
     my $ipc = AnyEvent::Open3::Simple->new(
       on_start => sub {
         my $proc = shift;       # isa AnyEvent::Open3::Simple::Process
         my $program = shift;    # string
         my @args = @_;          # list of arguments
         say 'child PID: ', $proc->pid;
       },
       on_stdout => sub {
         my $proc = shift;       # isa AnyEvent::Open3::Simple::Process
         my $line = shift;       # string
         say 'out: ', $string;
       },
       on_stderr => sub {
         my $proc = shift;       # isa AnyEvent::Open3::Simple::Process
         my $line = shift;       # string
         say 'err: ', $line;
       },
       on_exit   => sub {
         my $proc = shift;       # isa AnyEvent::Open3::Simple::Process
         my $exit_value = shift; # integer
         my $signal = shift;     # integer
         say 'exit value: ', $exit_value;
         say 'signal:     ', $signal;
         $done->send;
       },
       on_error => sub {
         my $error = shift;      # the exception thrown by IPC::Open3::open3
         my $program = shift;    # string
         my @args = @_;          # list of arguments
         warn "error: $error";
         $done->send;
       },
     );
     
     $ipc->run('echo', 'hello there');
     $done->recv;

DESCRIPTION

    This module provides an interface to open3 while running under AnyEvent
    that delivers data from stdout and stderr as lines are written by the
    subprocess. The interface is reminiscent of IPC::Open3::Simple,
    although this module does provides a somewhat different API, so it
    cannot be used a drop in replacement for that module.

    There are already a number of interfaces for interacting with
    subprocesses in the context of AnyEvent, but this one is the most
    convenient for my usage. Note the modules listed in the SEE ALSO
    section below for other interfaces that may be more or less
    appropriate.

CONSTRUCTOR

    Constructor takes a hash or hashref of event callbacks and attributes.
    Event callbacks have an on_ prefix, attributes do not.

 ATTRIBUTES

      * implementation

      The implementation to use for detecting process termination. This
      should be one of child, idle or mojo. On all platforms except for
      Microsoft Windows (but not Cygwin) the default is child.

      You can change the default by setting the ANYEVENT_OPEN3_SIMPLE
      environment variable, like this:

       % export ANYEVENT_OPEN3_SIMPLE=idle

      The mojo implementation is experimental and allows you to use
      AnyEvent::Open3::Simple with Mojolicious but without EV (which is
      usually required for AnyEvent, Mojolicious interaction).

 EVENTS

    These events will be triggered by the subprocess when the run method is
    called. Each event callback (except on_error) gets passed in an
    instance of AnyEvent::Open3::Simple::Process as its first argument
    which can be used to get the PID of the subprocess, or to write to it.
    on_error does not get a process object because it indicates an error in
    the creation of the process.

    Not all of these events will fire depending on the execution of the

README  view on Meta::CPAN

    loop.

    You may optionally provide the full content of standard input as a
    string reference or list reference as the last argument (or second to
    last if you are providing a callback below). If provided as a list
    reference, it will be joined by new lines in whatever format is native
    to your Perl. Currently on (non cygwin) Windows (Strawberry,
    ActiveState) this is the only way to provide standard input to the
    subprocess.

    Do not mix the use of passing standard input to run and
    AnyEvent::Open3::Simple::Process#print or
    AnyEvent::Open3::Simple::Process#say, otherwise bad things may happen.

    In version 0.80 or better, you may provide a callback as the last
    argument which is called before on_start, and takes the process object
    as its only argument. For example:

     foreach my $i (1..10)
     {
       $ipc->run($prog, @args, \$stdin, sub {
         my($proc) = @_;
         $proc->user({ iteration => $i });
       });
     }

    This is useful for making data accessible to $ipc object's callbacks
    that may be out of scope otherwise.

CAVEATS

    Some AnyEvent implementations may not work properly with the method
    used by AnyEvent::Open3::Simple to wait for the child process to
    terminate. See "CHILD PROCESS WATCHERS" in AnyEvent for details.

    This module uses an idle watcher instead of a child watcher to detect
    program termination on Microsoft Windows (but not Cygwin). This is
    because the child watchers are unsupported by AnyEvent on Windows. The
    idle watcher implementation seems to pass the test suite, but there may
    be some traps for the unwary. There may be other platforms or event
    loops where this is the appropriate choice, and you can use the
    ANYEVENT_OPEN3_SIMPLE environment variable or the implementation
    attribute to force it use an idle watcher instead. Patches for
    detecting environments where idle watchers should be used are welcome
    and encouraged.

    As of version 0.85, this module works on Windows with
    AnyEvent::Impl::EV, AnyEvent::Impl::Event and AnyEvent::Impl::Perl
    (possibly others), although in the past they have either not worked or
    had limitations placed on them. Because the author of AnyEvent does not
    hold the native Windows port of Perl in high regard: problems such as
    this may pop up again in the future and may not be addressed, and may
    be out of the control of the author of this module.

    Performance for the idle watcher implementation on native Windows
    (non-Cygwin) is almost certainly suboptimal, but the author of this
    module uses it and finds it useful despite this.

    Writing to a subprocesses stdin with
    AnyEvent::Open3::Simple::Process#print or
    AnyEvent::Open3::Simple::Process#say is unsupported on Microsoft
    Windows (it does work under Cygwin though).

    There are some traps for the unwary relating to buffers and deadlocks,
    IPC::Open3 is recommended reading.

    If you register a call back for on_exit, but not on_error then use a
    condition variable to wait for the process to complete as in this:

     my $cv = AnyEvent->condvar;
     my $ipc = AnyEvent::Open3::Simple->new(
       on_exit => sub { $cv->send },
     );
     $ipc->run('command_not_found');
     $cv->recv;

    You might be waiting forever if there is an error starting the process
    (if for example you give it a bad command). To handle this situation
    you might use croak on the condition variable in the event of error:

     my $cv = AnyEvent->condvar;
     my $ipc = AnyEvent::Open3::Simple->new(
       on_exit => sub { $cv->send },
       on_error => sub {
         my $error = shift;
         $cv->croak($error);
       },
     );
     $ipc->run('command_not_found');
     $cv->recv;

    This will cause the recv to die, printing a useful diagnostic if the
    exception isn't caught somewhere else.

SEE ALSO

    AnyEvent::Open3::Simple::Process

      Represents a process being run by this module, typically passed into
      the callbacks.

    AnyEvent::Subprocess

      Alternative to this module.

    AnyEvent::Run

      Alternative to this module.

AUTHOR

    Author: Graham Ollis <plicease@cpan.org>

    Contributors:

    Stephen R. Scaffidi

    Scott Wiersdorf

    Graham Knop (HAARG)