HTML::Mason::Request - Mason Request Class
$m->abort (...) $m->comp (...) etc.
The Request API is your gateway to all Mason features not provided by
syntactic tags. Mason creates a new Request object for every web
request. Inside a component you access the current request object via
the global $m
. Outside of a component, you can use the class
method instance
.
The methods Request->comp, Request->comp_exists, and Request->fetch_comp take a component path argument. Component paths are like URL paths, and always use a forward slash (/) as the separator, regardless of what your operating system uses.
my $fh = new IO::File ">mason.out"; ... out_method => sub { $fh->print($_[0]) }
By default, out_method prints to standard output. When the
HTML::Mason::ApacheHandler module is used, the out method uses the <
$r-
print >> method to send output.
Interp::exec
; in a web environment, this ultimately
becomes the HTTP status code.
abort
is implemented by throwing an HTML::Mason::Exception::Abort
object and can thus be caught by eval(). The aborted
method is a
shortcut for determining whether a caught error was generated by
abort
.
$err
was generated by abort
. If no $err
was passed, use $@
.
In this code, we catch and process fatal errors while letting abort
exceptions pass through:
eval { code_that_may_fail_or_abort() }; if ($@) { die $@ if $m->aborted;
# handle fatal errors...
$@
can lose its value quickly, so if you are planning to call
$m->aborted more than a few lines after the eval, you should save $@
to a temporary variable.
base_comp
is dynamically set to that
component until call_method exits. See Object-Oriented Techniques in the Component Developer's Guide for examples of usage.
$m->cache
returns a new cache object with a namespace specific
to this component.
cache_class specifies the class of cache object to create. It defaults to Cache::FileCache in most cases, or Cache::MemoryCache if the interpreter has no data directory, and must be a subclass of Cache::Cache. If cache_class does not contain a ``::'', the prefix ``Cache::'' is automatically prepended.
cache_options may include any valid options to the new()
method of
the cache class. e.g. for Cache::FileCache, valid options include
default_expires_in and cache_depth.
See the data caching in the Component Developer's Guide for examples and caching strategies. See the Cache::Cache documentation for a complete list of options and methods.
$m->cache_self
caches the entire output and return result of a
component.
It takes all of the options which can be passed to the cache method, plus two additional options:
cache_self
either returns undef, or a list containing the
return value of the component followed by '1'. You should return
immediately upon getting the latter result, as this indicates
that you are inside the second invocation of the component.
To cache the component's output:
<%init> return if $m->cache_self(expires_in => '3 hours'[, key => 'fookey']); ... <rest of init> ... </%init>
To cache the component's scalar return value:
<%init> my ($result, $cached) = $m->cache_self(expires_in => '3 hours'[, key => 'fookey']);
return $result if $cached; ... <rest of init> ... </%init>
To cache the component's list return value:
<%init> my (@retval) = $m->cache_self(expires_in => '3 hours'[, key => 'fookey']);
return @retval if pop @retval; ... <rest of init> ... </%init>
We call pop
on @retval
to remove the mandatory '1' at the end of
the list.
$m->caller_args(0) # arguments passed to current component $m->caller_args(1) # arguments passed to component that called us $m->caller_args(-1) # arguments passed to first component executed
When called in scalar context, a hash reference is returned. When called in list context, a list of arguments (which may be assigned to a hash) is returned.
my @comps = $m->callers # all components $m->callers(0) # current component $m->callers(1) # component that called us $m->callers(-1) # first component executed
$m->comp
in terms of return value and
scalar/list context. See the autohandlers section in the Component Developer's Guide for
examples.
clear_buffer is, of course, thwarted by flush_buffer
.
Components work exactly like Perl subroutines in terms of return
values and context. A component can return any type of value, which is
then returned from the $m->comp
call.
The <& &> tag provides a convenient shortcut for $m->comp
.
As of 1.10, component calls can accept an initial hash reference of
modifiers. The only currently supported modifier is store
, which
stores the component's output in a scalar reference. For example:
my $buf; my $return = $m->comp( { store => \$buf }, '/some/comp', type => 'big' );
This mostly duplicates the behavior of scomp, but can be useful in rare cases where you need to capture both a component's output and return value.
This modifier can be used with the <& &> tag as well, for example:
<& { store => \$buf }, '/some/comp', size => 'medium' &>
Returns undef if there is no content.
Interp::exec
path when the dhandler directory is
removed. Otherwise returns undef.
dhandler_arg
may be called from any component in the request, not just
the dhandler.
The default format within mod_perl and CGI environments is either line or html depending on whether the error mode is fatal or output, respectively. The default for standalone mode is text.
The formats correspond to HTML::Mason::Exception methods named as_format. You can define your own format by creating an appropriately named method; for example, to define an ``xml'' format, create a method HTML::Mason::Exception::as_xml patterned after one of the built-in methods.
The default mode within mod_perl and CGI environments is output, causing the error will be displayed in HTML form in the browser. The default for standalone mode is fatal.
A request can only be executed once; e.g. it is an error to call this recursively on the same request.
$r->rflush
to flush
the Apache buffer. Flushing the initial bytes of output can make your
servers appear more responsive.
Attempts to flush the buffers are ignored within the context of a call
to $m->scomp
or when output is being stored in a scalar
reference, as with the { store =
\$out } > component call
modifier.
Additionally, if a component has a <%filter>
block, that
component is buffered until its entire output is generated. This
means that inside that component and any components that it calls,
the buffer cannot be flushed.
HTML::Mason:::Request
currently in
use. If called when no Mason request is active it will return
undef
.
If called inside a subrequest, it returns the subrequest object.
autoflush
and out_method
. These
values may be overridden by passing parameters to this method.
See the Subrequests section in the Component Developer's Guide for more details about the subrequest feature.
$m->print
.
$m->print
is useful
if you need to output something in the middle of a Perl block.
In 1.1 and on, print
and $r->print
are remapped to $m->print
,
so they may be used interchangeably. Before 1.1, one should only use
$m->print
.
$m->comp
, but returns the component output as a string
instead of printing it. (Think sprintf versus printf.) The
component's return value is discarded.
$m->call_next
chain.
These additional methods are available when running Mason with mod_perl and the ApacheHandler.
See the Sending HTTP Headers section of the Component Developer's Guide for details about the automatic header feature.
This method is available when Mason is running under either the ApacheHandler or CGIHandler modules.
args_method
parameter. If you are using the
'mod_perl' args method, then calling this method is a fatal error.
See the ApacheHandler and
CGIHandler documentation for more details.
Jonathan Swartz <swartz@pobox.com>, Dave Rolsky <autarch@urth.org>, Ken Williams <ken@mathforum.org>