1IO::Wrap(3)           User Contributed Perl Documentation          IO::Wrap(3)
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NAME

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

9          use IO::Wrap;
10
11          ### Do stuff with any kind of filehandle (including a bare globref), or
12          ### any kind of blessed object that responds to a print() message.
13          ###
14          sub do_stuff {
15              my $fh = shift;
16
17              ### At this point, we have no idea what the user gave us...
18              ### a globref? a FileHandle? a scalar filehandle name?
19
20              $fh = wraphandle($fh);
21
22              ### At this point, we know we have an IO::Handle-like object!
23
24              $fh->print("Hey there!");
25              ...
26          }
27

DESCRIPTION

29       Let's say you want to write some code which does I/O, but you don't
30       want to force the caller to provide you with a FileHandle or IO::Handle
31       object.  You want them to be able to say:
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33           do_stuff(\*STDOUT);
34           do_stuff('STDERR');
35           do_stuff($some_FileHandle_object);
36           do_stuff($some_IO_Handle_object);
37
38       And even:
39
40           do_stuff($any_object_with_a_print_method);
41
42       Sure, one way to do it is to force the caller to use tiehandle().  But
43       that puts the burden on them.  Another way to do it is to use IO::Wrap,
44       which provides you with the following functions:
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46       wraphandle SCALAR
47           This function will take a single argument, and "wrap" it based on
48           what it seems to be...
49
50           *   A raw scalar filehandle name, like "STDOUT" or "Class::HANDLE".
51               In this case, the filehandle name is wrapped in an IO::Wrap
52               object, which is returned.
53
54           *   A raw filehandle glob, like "\*STDOUT".  In this case, the
55               filehandle glob is wrapped in an IO::Wrap object, which is
56               returned.
57
58           *   A blessed FileHandle object.  In this case, the FileHandle is
59               wrapped in an IO::Wrap object if and only if your FileHandle
60               class does not support the "read()" method.
61
62           *   Any other kind of blessed object, which is assumed to be
63               already conformant to the IO::Handle interface.  In this case,
64               you just get back that object.
65
66       If you get back an IO::Wrap object, it will obey a basic subset of the
67       IO:: interface.  That is, the following methods (note: I said methods,
68       not named operators) should work on the thing you get back:
69
70           close
71           getline
72           getlines
73           print ARGS...
74           read BUFFER,NBYTES
75           seek POS,WHENCE
76           tell
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NOTES

79       Clearly, when wrapping a raw external filehandle (like \*STDOUT), I
80       didn't want to close the file descriptor when the "wrapper" object is
81       destroyed... since the user might not appreciate that!  Hence, there's
82       no DESTROY method in this class.
83
84       When wrapping a FileHandle object, however, I believe that Perl will
85       invoke the FileHandle::DESTROY when the last reference goes away, so in
86       that case, the filehandle is closed if the wrapped FileHandle really
87       was the last reference to it.
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WARNINGS

90       This module does not allow you to wrap filehandle names which are given
91       as strings that lack the package they were opened in. That is, if a
92       user opens FOO in package Foo, they must pass it to you either as
93       "\*FOO" or as "Foo::FOO".  However, "STDIN" and friends will work just
94       fine.
95

VERSION

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

100       Primary Maintainer
101           David F. Skoll (dfs@roaringpenguin.com).
102
103       Original Author
104           Eryq (eryq@zeegee.com).  President, ZeeGee Software Inc
105           (http://www.zeegee.com).
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109perl v5.8.8                       2005-02-10                       IO::Wrap(3)