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.IX Title "IPC::Run::IO 3pm"
.TH IPC::Run::IO 3pm 2024-04-01 "perl v5.38.2" "User Contributed Perl Documentation"
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.\" way too many mistakes in technical documents.
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.nh
.SH NAME
IPC::Run::IO \-\- I/O channels for IPC::Run.
.SH SYNOPSIS
.IX Header "SYNOPSIS"
\&\fBNOT IMPLEMENTED YET ON Win32! Win32 does not allow select() on
normal file descriptors; IPC::RUN::IO needs to use IPC::Run::Win32Helper
to do this.\fR
.PP
.Vb 1
\&   use IPC::Run qw( io );
\&
\&   ## The sense of \*(Aq>\*(Aq and \*(Aq<\*(Aq is opposite of perl\*(Aqs open(),
\&   ## but agrees with IPC::Run.
\&   $io = io( "filename", \*(Aq>\*(Aq,  \e$recv );
\&   $io = io( "filename", \*(Aqr\*(Aq,  \e$recv );
\&
\&   ## Append to $recv:
\&   $io = io( "filename", \*(Aq>>\*(Aq, \e$recv );
\&   $io = io( "filename", \*(Aqra\*(Aq, \e$recv );
\&
\&   $io = io( "filename", \*(Aq<\*(Aq,  \e$send );
\&   $io = io( "filename", \*(Aqw\*(Aq,  \e$send );
\&
\&   $io = io( "filename", \*(Aq<<\*(Aq, \e$send );
\&   $io = io( "filename", \*(Aqwa\*(Aq, \e$send );
\&
\&   ## Handles / IO objects that the caller opens:
\&   $io = io( \e*HANDLE,   \*(Aq<\*(Aq,  \e$send );
\&
\&   $f = IO::Handle\->new( ... ); # Any subclass of IO::Handle
\&   $io = io( $f, \*(Aq<\*(Aq, \e$send );
\&
\&   require IPC::Run::IO;
\&   $io = IPC::Run::IO\->new( ... );
\&
\&   ## Then run(), harness(), or start():
\&   run $io, ...;
\&
\&   ## You can, of course, use io() or IPC::Run::IO\->new() as an
\&   ## argument to run(), harness, or start():
\&   run io( ... );
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
This class and module allows filehandles and filenames to be harnessed for
I/O when used IPC::Run, independent of anything else IPC::Run is doing
(except that errors & exceptions can affect all things that IPC::Run is
doing).
.SH SUBCLASSING
.IX Header "SUBCLASSING"
INCOMPATIBLE CHANGE: due to the awkwardness introduced in ripping pseudohashes
out of Perl, this class \fIno longer\fR uses the fields pragma.
.SH SUBROUTINES
.IX Header "SUBROUTINES"
.IP new 4
.IX Item "new"
I think it takes >> or << along with some other data.
.Sp
TODO: Needs more thorough documentation. Patches welcome.
.IP filename 4
.IX Item "filename"
Gets/sets the filename.  Returns the value after the name change, if
any.
.IP init 4
.IX Item "init"
Does initialization required before this can be run.  This includes \fBopen()\fRing
the file, if necessary, and clearing the destination scalar if necessary.
.IP open 4
.IX Item "open"
If a filename was passed in, opens it.  Determines if the handle is open
via \fBfileno()\fR.  Throws an exception on error.
.IP open_pipe 4
.IX Item "open_pipe"
If this is a redirection IO object, this opens the pipe in a platform
independent manner.
.IP close 4
.IX Item "close"
Closes the handle.  Throws an exception on failure.
.IP fileno 4
.IX Item "fileno"
Returns the fileno of the handle.  Throws an exception on failure.
.IP mode 4
.IX Item "mode"
Returns the operator in terms of 'r', 'w', and 'a'.  There is a state
\&'ra', unlike Perl's \fBopen()\fR, which indicates that data read from the
handle or file will be appended to the output if the output is a scalar.
This is only meaningful if the output is a scalar, it has no effect if
the output is a subroutine.
.Sp
The redirection operators can be a little confusing, so here's a reference
table:
.Sp
.Vb 6
\&   >      r      Read from handle in to process
\&   <      w      Write from process out to handle
\&   >>     ra     Read from handle in to process, appending it to existing
\&                 data if the destination is a scalar.
\&   <<     wa     Write from process out to handle, appending to existing
\&                 data if IPC::Run::IO opened a named file.
.Ve
.IP op 4
.IX Item "op"
Returns the operation: '<', '>', '<<', '>>'.  See "mode" if you want
to spell these 'r', 'w', etc.
.IP binmode 4
.IX Item "binmode"
Sets/gets whether this pipe is in binmode or not.  No effect off of Win32
OSs, of course, and on Win32, no effect after the harness is \fBstart()\fRed.
.IP dir 4
.IX Item "dir"
Returns the first character of \f(CW$self\fR\->op.  This is either "<" or ">".
.IP poll 4
.IX Item "poll"
TODO: Needs confirmation that this is correct. Was previously undocumented.
.Sp
I believe this is polling the IO for new input and then returns undef if there will never be any more input, 0 if there is none now, but there might be in the future, and TRUE if more input was gotten.
.SH AUTHOR
.IX Header "AUTHOR"
Barrie Slaymaker <barries@slaysys.com>
.SH TODO
.IX Header "TODO"
Implement bidirectionality.