لطفا منتظر باشید ...
 |  |
8.114. Filter::Util::Call
Provides a framework for implementing
source filters in Perl code. While you may use Filter::Util::Call
directly, we suggest you use Filter::Simple instead.
For example:package Milter; # Could just as well be called 'OldJoke'
use Filter::Util::Call ;
sub import {
my($type) = @_ ;
filter_add(bless []) ;
}
sub filter {
my($self) = @_;
my($status);
s/Shut-Up/Trouble/g
if ($status = filter_read()) > 0;
$status ;
}
1;
You'd use the above in your code like so:#!/usr/local/bin/perl -w
use Milter;
print "Are you looking for Shut-Up?\n" ;
This prints:Are you looking for Trouble?
Filter::Util::Call implements the following methods.
| filter |
filter()
Performs the main processing for the filter. Used with closure
filters; that is, a closure filter handles the lexical variables that
are maintained by the closure. The finished source, as processed by
filter, will be returned in $_.
filter returns a status, as follows:< 0
An error has been encountered.EOF
End-of-file has been reached unexpectedly.> 0
Everything is OK.
| filter_add |
filter_add(ref)
Installs the filter. filter_add takes one
parameter, a reference, and depending on the kind of reference used,
dictates which of the two filter types is used. CODE references
result in a closure filter; otherwise, method filters are assumed.
| filter_del |
filter_del()
Disables the current filter. It doesn't destroy any
filters, just tells Perl to stop using them.
| filter_read |
filter_read(n)
Obtains a line or block from the next filter in the chain. If there
are no other filters, then the actual source file is obtained. For
example:
$status = filter_read(); # Requests a line
$status = filter_read($size); # Requests a block of $size
| filter_read_exact |
filter_read_exact()
Obtains a line or block from the next filter in the chain. If there
are no other filters, then the actual source file is obtained.
| import |
import()
Creates an instance of the filter. Perl calls
import indirectly when it encounters use
Milter in your Perl program. import will
always have one parameter passed by Perl, which corresponds to the
name of your package—in this case, Milter.
So, if you do this:use Milter qw(pinta nina santa-maria);You get in @_:@_[0] => "Milter"
@_[1] => "pinta"
@_[2] => "nina"
@_[3] => "santa-maria"import then calls filter_add
before finishing.
|  | |
| 8.113. Filter::Simple |  | 8.115. FindBin |
Copyright © 2002 O'Reilly & Associates. All rights reserved.
