MIME::Body(3) User Contributed Perl Documentation MIME::Body(3)
NAME
MIME::Body - the body of a MIME message
SYNOPSIS
Before reading further, you should see MIME::Tools to make sure that
you understand where this module fits into the grand scheme of things.
Go on, do it now. I'll wait.
Ready? Ok...
Obtaining bodies
### Get the bodyhandle of a MIME::Entity object:
$body = $entity->bodyhandle;
### Create a body which stores data in a disk file:
$body = new MIME::Body::File "/path/to/file";
### Create a body which stores data in an in-core array:
$body = new MIME::Body::InCore \@strings;
Opening, closing, and using IO handles
### Write data to the body:
$IO = $body->open("w") || die "open body: $!";
$IO->print($message);
$IO->close || die "close I/O handle: $!";
### Read data from the body (in this case, line by line):
$IO = $body->open("r") || die "open body: $!";
while (defined($_ = $IO->getline)) {
### do stuff
}
$IO->close || die "close I/O handle: $!";
Other I/O
### Dump the ENCODED body data to a filehandle:
$body->print(\*STDOUT);
### Slurp all the UNENCODED data in, and put it in a scalar:
$string = $body->as_string;
### Slurp all the UNENCODED data in, and put it in an array of lines:
@lines = $body->as_lines;
Working directly with paths to underlying files
### Where's the data?
if (defined($body->path)) { ### data is on disk:
print "data is stored externally, in ", $body->path;
}
else { ### data is in core:
print "data is already in core, and is...\n", $body->as_string;
}
### Get rid of anything on disk:
$body->purge;
DESCRIPTION
MIME messages can be very long (e.g., tar files, MPEGs, etc.) or very
short (short textual notes, as in ordinary mail). Long messages are
best stored in files, while short ones are perhaps best stored in core.
This class is an attempt to define a common interface for objects which
contain message data, regardless of how the data is physically stored.
The lifespan of a "body" object usually looks like this:
1. Body object is created by a MIME::Parser during parsing. It's at
this point that the actual MIME::Body subclass is chosen, and new()
is invoked. (For example: if the body data is going to a file,
then it is at this point that the class MIME::Body::File, and the
filename, is chosen).
2. Data is written to the body (usually by the MIME parser) like this:
The body is opened for writing, via "open("w")". This will trash
any previous contents, and return an "I/O handle" opened for
writing. Data is written to this I/O handle, via print(). Then
the I/O handle is closed, via close().
3. Data is read from the body (usually by the user application) like
this: The body is opened for reading by a user application, via
"open("r")". This will return an "I/O handle" opened for reading.
Data is read from the I/O handle, via read(), getline(), or
getlines(). Then the I/O handle is closed, via close().
4. Body object is destructed.
You can write your own subclasses, as long as they follow the interface
described below. Implementers of subclasses should assume that steps 2
and 3 may be repeated any number of times, and in different orders
(e.g., 1-2-2-3-2-3-3-3-3-3-2-4).
In any case, once a MIME::Body has been created, you ask to open it for
reading or writing, which gets you an "i/o handle": you then use the
same mechanisms for reading from or writing to that handle, no matter
what class it is.
Beware: unless you know for certain what kind of body you have, you
should not assume that the body has an underlying filehandle.
PUBLIC INTERFACE
new ARGS...
Class method, constructor. Create a new body. Any ARGS are sent
to init().
init ARGS...
Instance method, abstract, initiallizer. This is called
automatically by "new()", with the arguments given to "new()". The
arguments are optional, and entirely up to the subclass. The
default method does nothing,
as_lines
Instance method. Return the contents of the body as an array of
lines (each terminated by a newline, with the possible exception of
the final one). Returns empty on failure (NB: indistinguishable
from an empty body!).
Note: the default method gets the data via repeated getline()
calls; your subclass might wish to override this.
as_string
Instance method. Return the body data as a string (slurping it
into core if necessary). Best not to do this unless you're sure
that the body is reasonably small! Returns empty string for an
empty body, and undef on failure.
Note: the default method uses print(), which gets the data via
repeated read() calls; your subclass might wish to override this.
binmode [ONOFF]
Instance method. With argument, flags whether or not open() should
return an I/O handle which has binmode() activated. With no
argument, just returns the current value.
is_encoded [ONOFF]
Instance method. If set to yes, no decoding is applied on output.
This flag is set by MIME::Parser, if the parser runs in
decode_bodies(0) mode, so the content is handled unmodified.
dup Instance method. Duplicate the bodyhandle.
Beware: external data in bodyhandles is not copied to new files!
Changing the data in one body's data file, or purging that body,
will affect its duplicate. Bodies with in-core data probably need
not worry.
open READWRITE
Instance method, abstract. This should do whatever is necessary to
open the body for either writing (if READWRITE is "w") or reading
(if mode is "r").
This method is expected to return an "I/O handle" object on
success, and undef on error. An I/O handle can be any object that
supports a small set of standard methods for reading/writing data.
See the IO::Handle class for an example.
path [PATH]
Instance method. If you're storing the body data externally (e.g.,
in a disk file), you'll want to give applications the ability to
get at that data, for cleanup. This method should return the path
to the data, or undef if there is none.
Where appropriate, the path should be a simple string, like a
filename. With argument, sets the PATH, which should be undef if
there is none.
print FILEHANDLE
Instance method. Output the body data to the given filehandle, or
to the currently-selected one if none is given.
purge
Instance method, abstract. Remove any data which resides external
to the program (e.g., in disk files). Immediately after a purge(),
the path() should return undef to indicate that the external data
is no longer available.
SUBCLASSES
The following built-in classes are provided:
Body Stores body When open()ed,
class: data in: returns:
--------------------------------------------------------
MIME::Body::File disk file IO::Handle
MIME::Body::Scalar scalar IO::Handle
MIME::Body::InCore scalar array IO::Handle
MIME::Body::File
A body class that stores the data in a disk file. Invoke the
constructor as:
$body = new MIME::Body::File "/path/to/file";
In this case, the "path()" method would return the given path, so you
could say:
if (defined($body->path)) {
open BODY, $body->path or die "open: $!";
while (<BODY>) {
### do stuff
}
close BODY;
}
But you're best off not doing this.
MIME::Body::Scalar
A body class that stores the data in-core, in a simple scalar. Invoke
the constructor as:
$body = new MIME::Body::Scalar \$string;
A single scalar argument sets the body to that value, exactly as though
you'd opened for the body for writing, written the value, and closed
the body again:
$body = new MIME::Body::Scalar "Line 1\nLine 2\nLine 3";
A single array reference sets the body to the result of joining all the
elements of that array together:
$body = new MIME::Body::Scalar ["Line 1\n",
"Line 2\n",
"Line 3"];
MIME::Body::InCore
A body class that stores the data in-core. Invoke the constructor as:
$body = new MIME::Body::InCore \$string;
$body = new MIME::Body::InCore $string;
$body = new MIME::Body::InCore \@stringarray
A simple scalar argument sets the body to that value, exactly as though
you'd opened for the body for writing, written the value, and closed
the body again:
$body = new MIME::Body::InCore "Line 1\nLine 2\nLine 3";
A single array reference sets the body to the concatenation of all
scalars that it holds:
$body = new MIME::Body::InCore ["Line 1\n",
"Line 2\n",
"Line 3"];
Defining your own subclasses
So you're not happy with files and scalar-arrays? No problem: just
define your own MIME::Body subclass, and make a subclass of
MIME::Parser or MIME::ParserBase which returns an instance of your body
class whenever appropriate in the "new_body_for(head)" method.
Your "body" class must inherit from MIME::Body (or some subclass of
it), and it must either provide (or inherit the default for) the
following methods...
The default inherited method should suffice for all these:
new
binmode [ONOFF]
path
The default inherited method may suffice for these, but perhaps there's
a better implementation for your subclass.
init ARGS...
as_lines
as_string
dup
print
purge
The default inherited method will probably not suffice for these:
open
NOTES
One reason I didn't just use IO::Handle objects for message bodies was
that I wanted a "body" object to be a form of completely encapsulated
program-persistent storage; that is, I wanted users to be able to write
code like this...
### Get body handle from this MIME message, and read its data:
$body = $entity->bodyhandle;
$IO = $body->open("r");
while (defined($_ = $IO->getline)) {
print STDOUT $_;
}
$IO->close;
...without requiring that they know anything more about how the $body
object is actually storing its data (disk file, scalar variable, array
variable, or whatever).
Storing the body of each MIME message in a persistently-open IO::Handle
was a possibility, but it seemed like a bad idea, considering that a
single multipart MIME message could easily suck up all the available
file descriptors on some systems. This risk increases if the user
application is processing more than one MIME entity at a time.
SEE ALSO
MIME::Tools(3)
AUTHOR
Eryq (eryq@zeegee.com), ZeeGee Software Inc (http://www.zeegee.com).
David F. Skoll (dfs@roaringpenguin.com) http://www.roaringpenguin.com
All rights reserved. This program is free software; you can
redistribute it and/or modify it under the same terms as Perl itself.
Thanks to Achim Bohnet for suggesting that MIME::Parser not be
restricted to the use of FileHandles.
#------------------------------ 1;
perl v5.10.0 2008-06-30 MIME::Body(3)
Mac OS X 10.6 - Generated Thu Sep 17 20:12:42 CDT 2009