io::atomicfile(3) [osx man page]

IO::AtomicFile(3)					User Contributed Perl Documentation					 IO::AtomicFile(3)

NAME

       IO::AtomicFile - write a file which is updated atomically

SYNOPSIS

	   use IO::AtomicFile;

	   ### Write a temp file, and have it install itself when closed:
	   my $FH = IO::AtomicFile->open("bar.dat", "w");
	   print $FH "Hello!
";
	   $FH->close || die "couldn't install atomic file: $!";

	   ### Write a temp file, but delete it before it gets installed:
	   my $FH = IO::AtomicFile->open("bar.dat", "w");
	   print $FH "Hello!
";
	   $FH->delete;

	   ### Write a temp file, but neither install it nor delete it:
	   my $FH = IO::AtomicFile->open("bar.dat", "w");
	   print $FH "Hello!
";
	   $FH->detach;

DESCRIPTION

       This module is intended for people who need to update files reliably in the face of unexpected program termination.

       For example, you generally don't want to be halfway in the middle of writing /etc/passwd and have your program terminate!  Even the act of
       writing a single scalar to a filehandle is not atomic.

       But this module gives you true atomic updates, via rename().  When you open a file /foo/bar.dat via this module, you are actually opening a
       temporary file /foo/bar.dat..TMP, and writing your output there.   The act of closing this file (either explicitly via close(), or
       implicitly via the destruction of the object) will cause rename() to be called... therefore, from the point of view of the outside world,
       the file's contents are updated in a single time quantum.

       To ensure that problems do not go undetected, the "close" method done by the destructor will raise a fatal exception if the rename() fails.
       The explicit close() just returns undef.

       You can also decide at any point to trash the file you've been building.

AUTHOR

   Primary Maintainer
       David F. Skoll (dfs@roaringpenguin.com).

   Original Author
       Eryq (eryq@zeegee.com).	President, ZeeGee Software Inc (http://www.zeegee.com).

REVISION

       $Revision: 1.2 $

perl v5.16.2							    2005-02-10							 IO::AtomicFile(3)

IO::Wrap(3)						User Contributed Perl Documentation					       IO::Wrap(3)

NAME

       IO::Wrap - wrap raw filehandles in IO::Handle interface

SYNOPSIS

	  use IO::Wrap;

	  ### Do stuff with any kind of filehandle (including a bare globref), or
	  ### any kind of blessed object that responds to a print() message.
	  ###
	  sub do_stuff {
	      my $fh = shift;

	      ### At this point, we have no idea what the user gave us...
	      ### a globref? a FileHandle? a scalar filehandle name?

	      $fh = wraphandle($fh);

	      ### At this point, we know we have an IO::Handle-like object!

	      $fh->print("Hey there!");
	      ...
	  }

DESCRIPTION

       Let's say you want to write some code which does I/O, but you don't want to force the caller to provide you with a FileHandle or IO::Handle
       object.	You want them to be able to say:

	   do_stuff(*STDOUT);
	   do_stuff('STDERR');
	   do_stuff($some_FileHandle_object);
	   do_stuff($some_IO_Handle_object);

       And even:

	   do_stuff($any_object_with_a_print_method);

       Sure, one way to do it is to force the caller to use tiehandle().  But that puts the burden on them.  Another way to do it is to use
       IO::Wrap, which provides you with the following functions:

       wraphandle SCALAR
	   This function will take a single argument, and "wrap" it based on what it seems to be...

	   o   A raw scalar filehandle name, like "STDOUT" or "Class::HANDLE".	In this case, the filehandle name is wrapped in an IO::Wrap
	       object, which is returned.

	   o   A raw filehandle glob, like "*STDOUT".	In this case, the filehandle glob is wrapped in an IO::Wrap object, which is returned.

	   o   A blessed FileHandle object.  In this case, the FileHandle is wrapped in an IO::Wrap object if and only if your FileHandle class
	       does not support the "read()" method.

	   o   Any other kind of blessed object, which is assumed to be already conformant to the IO::Handle interface.  In this case, you just
	       get back that object.

       If you get back an IO::Wrap object, it will obey a basic subset of the IO:: interface.  That is, the following methods (note: I said
       methods, not named operators) should work on the thing you get back:

	   close
	   getline
	   getlines
	   print ARGS...
	   read BUFFER,NBYTES
	   seek POS,WHENCE
	   tell

NOTES

       Clearly, when wrapping a raw external filehandle (like *STDOUT), I didn't want to close the file descriptor when the "wrapper" object is
       destroyed... since the user might not appreciate that!  Hence, there's no DESTROY method in this class.

       When wrapping a FileHandle object, however, I believe that Perl will invoke the FileHandle::DESTROY when the last reference goes away, so
       in that case, the filehandle is closed if the wrapped FileHandle really was the last reference to it.

WARNINGS

       This module does not allow you to wrap filehandle names which are given as strings that lack the package they were opened in. That is, if a
       user opens FOO in package Foo, they must pass it to you either as "*FOO" or as "Foo::FOO".  However, "STDIN" and friends will work just
       fine.

VERSION

       $Id: Wrap.pm,v 1.2 2005/02/10 21:21:53 dfs Exp $

AUTHOR

       Primary Maintainer
	   David F. Skoll (dfs@roaringpenguin.com).

       Original Author
	   Eryq (eryq@zeegee.com).  President, ZeeGee Software Inc (http://www.zeegee.com).

POD ERRORS

       Hey! The above document had some coding errors, which are explained below:

       Around line 212:
	   '=item' outside of any '=over'

	   =over without closing =back

perl v5.18.2							    2005-02-10							       IO::Wrap(3)