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HTML::Mason::Params - Mason configuration parameters
This document lists all of the Mason configuration parameters that are
intended to be used by end users.
Each parameter has two names: a Perl version and an Apache version.
The Perl version uses lowercase_with_underscores, while the Apache
version uses StudlyCaps with a Mason prefix. The conversion from
one version to the other is otherwise very predictable. For example,
-
autohandler_name <--> MasonAutohandlerName
-
comp_root <--> MasonCompRoot
-
data_cache_defaults <--> MasonDataCacheDefaults
The Apache parameter names are used in the Apache configuration file
in an httpd-based configuration.
The Perl parameter names are used from Perl code, i.e. anywhere other
than the Apache configuration file. For example,
List of variable names, complete with prefix ($@%), that you intend
to use as globals in components. Normally global variables are
forbidden by strict, but any variable mentioned in this list is
granted a reprieve via a ``use vars'' statement. For example:
allow_globals => [qw($DBH %session)]
In a mod_perl environment, $r (the request object) is automatically
added to this list.
Title that you want this ApacheHandler to appear as under
Apache::Status. Default is ``HTML::Mason status''. This is useful if
you create more than one ApacheHandler object and want them all
visible via Apache::Status.
Method to use for unpacking GET and POST arguments. The valid options
are 'CGI' and 'mod_perl'; these indicate that a CGI.pm or
Apache::Request object (respectively) will be created for the
purposes of argument handling.
'mod_perl' is the default under mod_perl-1 and requires that you have
installed the Apache::Request package. Under mod_perl-2, the default
is 'CGI' because Apache2::Request is still in development.
If args_method is 'mod_perl', the $r global is upgraded to an
Apache::Request object. This object inherits all Apache methods and
adds a few of its own, dealing with parameters and file uploads. See
Apache::Request for more information.
If the args_method is 'CGI', the Mason request object ($m) will have a
method called cgi_object available. This method returns the CGI
object used for argument processing.
While Mason will load Apache::Request or CGI as needed at runtime, it
is recommended that you preload the relevant module either in your
httpd.conf or handler.pl file, as this will save some memory.
True or false, default is true. Indicates whether Mason should
automatically send HTTP headers before sending content back to the
client. If you set to false, you should call $r->send_http_header
manually.
See the sending HTTP headers section of the developer's manual for more details about the automatic
header feature.
NOTE: This parameter has no effect under mod_perl-2, since calling
$r->send_http_header is no longer needed.
True or false, default is false. Indicates whether to flush the output
buffer ($m->flush_buffer) after every string is output. Turn on
autoflush if you need to send partial output to the client, for
example in a progress meter.
As of Mason 1.3, autoflush will only work if enable_autoflush has
been set. Components can be compiled more efficiently if they don't
have to check for autoflush. Before using autoflush you might consider
whether a few manual $m->flush_buffer calls would work nearly
as well.
File name used for
autohandlers. Default is
``autohandler''. If this is set to an empty string (``'') then
autohandlers are turned off entirely.
Number of bytes to preallocate in the output buffer for each request.
Defaults to 0. Setting this to, say, your maximum page size (or close
to it) can reduce the number of reallocations Perl performs as
components add to the output buffer.
Specifies the maximum number of components that should be held in the
in-memory code cache. The default is 'unlimited', meaning no
components will ever be discarded; Mason can perform certain
optimizations in this mode. Setting this to zero disables the code
cache entirely. See the code cache
section of the administrator's manual for further details.
The class into which component objects are blessed. This defaults to
HTML::Mason::Component.
The component root marks the top of your component hierarchy and
defines how component paths are translated into real file paths. For
example, if your component root is /usr/local/httpd/docs, a component
path of /products/index.html translates to the file
/usr/local/httpd/docs/products/index.html.
Under Apache and
CGI, comp_root defaults to the server's
document root. In standalone mode comp_root defaults to the current
working directory.
This parameter may be either a scalar or an array reference. If it is
a scalar, it should be a filesystem path indicating the component
root. If it is an array reference, it should be of the following form:
[ [ foo => '/usr/local/foo' ],
[ bar => '/usr/local/bar' ] ]
This is an array of two-element array references, not a hash. The
``keys'' for each path must be unique and their ``values'' must be
filesystem paths. These paths will be searched in the provided order
whenever a component path is resolved. For example, given the above
component roots and a component path of /products/index.html, Mason
would search first for /usr/local/foo/products/index.html, then for
/usr/local/bar/products/index.html.
The keys are used in several ways. They help to distinguish component
caches and object files between different component roots, and they
appear in the title() of a component.
When you specify a single path for a component root, this is actually
translated into
[ [ MAIN => path ] ]
If you have turned on dynamic_comp_root, you may modify the
component root(s) of an interpreter between requests by calling
$interp->comp_root with a value. However, the path associated
with any given key may not change between requests. For example,
if the initial component root is
[ [ foo => '/usr/local/foo' ],
[ bar => '/usr/local/bar' ], ]
then it may not be changed to
[ [ foo => '/usr/local/bar' ],
[ bar => '/usr/local/baz' ],
but it may be changed to
[ [ foo => '/usr/local/foo' ],
[ blarg => '/usr/local/blarg' ] ]
In other words, you may add or remove key/path pairs but not modify an
already-used key/path pair. The reason for this restriction is that
the interpreter maintains a component cache per key that would become
invalid if the associated paths were to change.
The class to use when creating a compiler. Defaults to
HTML::Mason::Compiler.
A code reference used to handle errors thrown during component
compilation or runtime. By default, this is a subroutine that turns
non-exception object errors in components into exceptions. If this
parameter is set to a false value, these errors are simply rethrown
as-is.
Turning exceptions into objects can be expensive, since this will
cause the generation of a stack trace for each error. If you are using
strings or unblessed references as exceptions in your code, you may
want to turn this off as a performance boost.
The $m->cache API to use. '1.1', the default, indicates the newer
API documented in this manual.
'1.0' indicates the old API documented in 1.0x and earlier. This
compatibility layer is provided as a convenience for users upgrading
from older versions of Mason, but will not be supported indefinitely.
A hash reference of default options to use for the $m->cache
command. For example, to use the MemoryCache implementation
by default,
data_cache_defaults => {cache_class => 'MemoryCache'}
These settings are overriden by options given to particular
$m->cache calls.
The data directory is a writable directory that Mason uses for various
features and optimizations: for example, component object files and
data cache files. Mason will create the directory on startup, if necessary, and set its
permissions according to the web server User/Group.
Under Apache, data_dir defaults to a
directory called ``mason'' under the Apache server root. You will
need to change this on certain systems that assign a high-level
server root such as /usr!
In non-Apache environments, data_dir has no default. If it is left
unspecified, Mason will not use object files, and the default
data cache class will be
MemoryCache instead of FileCache.
True or false, default is true. Indicates whether Mason should decline
directory requests, leaving Apache to serve up a directory index or a
FORBIDDEN error as appropriate. See the allowing directory requests section of the administrator's manual
for more information about handling directories with Mason.
Escape flags to apply to all <% %> expressions by default. The current
valid flags are
h - escape for HTML ('<' => '<', etc.)
u - escape for URL (':' => '%3A', etc.)
The developer can override default escape flags on a per-expression
basis; see the escaping expressions section of the developer's manual.
If you want to set multiple flags as the default, this should be
given as a reference to an array of flags.
One of ``always'', ``auto'', or ``never''. This determines whether or not
an %ARGS hash is created in components. If it is set to ``always'',
one is always defined. If set to ``never'', it is never defined.
The default, ``auto'', will cause the hash to be defined only if some
part of the component contains the string ``ARGS''. This is somewhat
crude, and may result in some false positives, but this is preferable
to false negatives.
Not defining the args hash means that we can avoid copying component
arguments, which can save memory and slightly improve execution speed.
File name used for dhandlers. Default
is ``dhandler''. If this is set to an empty string (``'') then dhandlers
are turned off entirely.
True or false, defaults to false. Indicates whether the comp_root
can be modified on this interpreter between requests. Mason can
perform a few optimizations with a fixed component root, so you
should only set this to true if you actually need it.
True or false, default is true. Indicates whether components are
compiled with support for autoflush. The component can be compiled
to a more efficient form if it does not have to check for autoflush
mode, so you should set this to 0 if you can.
Indicates how errors are formatted. The built-in choices are
-
brief - just the error message with no trace information
-
text - a multi-line text format
-
line - a single-line text format, with different pieces of information separated by tabs (useful for log files)
-
html - a fancy html format
The default format under Apache and
CGI 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.
Indicates how errors are returned to the caller. The choices are
fatal, meaning die with the error, and output, meaning output
the error just like regular output.
The default under Apache and
CGI is output, causing the error to be
displayed in the browser. The default for standalone mode is
fatal.
A hash reference of escape flags to set for this object. See the
section on the set_escape method for more details.
Regular expression indicating which warnings to ignore when loading
components. Any warning that is not ignored will prevent the
component from being loaded and executed. For example:
ignore_warnings_expr =>
'Global symbol.*requires explicit package'
If set to undef, all warnings are heeded. If set to '.', warnings
are turned off completely as a specially optimized case.
By default, this is set to 'Subroutine .* redefined'. This allows you
to declare global subroutines inside <%once> sections and not receive
an error when the component is reloaded.
This is the package in which a component's code is executed. For
historical reasons, this defaults to HTML::Mason::Commands.
The class to use when creating a interpreter. Defaults to
HTML::Mason::Interp.
The class to use when creating a lexer. Defaults to HTML::Mason::Lexer.
The maximum recursion depth for the component stack, for the request
stack, and for the inheritance stack. An error is signalled if the
maximum is exceeded. Default is 32.
When compiling a component, use uniquely named subroutines for the a
component's body, subcomponents, and methods. Doing this allows you to
effectively profile Mason components. Without this, all components
simply show up as __ANON__ or something similar in the profiler.
Extension to add to the end of object files. Default is ``.obj''.
Indicates where to send output. If out_method is a reference to a
scalar, output is appended to the scalar. If out_method is a
reference to a subroutine, the subroutine is called with each output
string. For example, to send output to a file called ``mason.out'':
my $fh = new IO::File ">mason.out";
...
out_method => sub { $fh->print($_[0]) }
By default, out_method prints to standard output. Under
Apache, standard output is
redirected to $r->print.
An array of plugins that will be called at various stages of request
processing. Please see HTML::Mason::Plugin for
details.
Text given for this parameter is placed at the end of each
component. See also preamble. The request will be available as
$m in postamble code.
Sub reference that is called to postprocess the Perl portion of a
compiled component, just before it is assembled into its final
subroutine form. The sub is called with a single parameter, a scalar
reference to the Perl portion of the component. The sub is expected
to process the string in-place. See also
preprocess and postprocess_text.
Sub reference that is called to postprocess the text portion of a
compiled component, just before it is assembled into its final
subroutine form. The sub is called with a single parameter, a scalar
reference to the text portion of the component. The sub is expected
to process the string in-place. See also
preprocess and postprocess_perl.
Text given for this parameter is placed at the beginning of each
component, but after the execution of any <%once> block. See
also postamble. The request will be available as $m in preamble
code.
A list of component paths, optionally with glob wildcards, to load
when the interpreter initializes. e.g.
preloads => ['/foo/index.html','/bar/*.pl']
Default is the empty list. For maximum performance, this should only
be used for components that are frequently viewed and rarely updated.
See the preloading components section of the administrator's manual for further details.
As mentioned in the developer's manual, a component's <%once>
section is executed when it is loaded. For preloaded components, this
means that this section will be executed before a Mason or Apache
request exist, so preloading a component that uses $m or $r in a
<%once> section will fail.
Sub reference that is called to preprocess each component before the compiler does
it's magic. The sub is called with a single parameter, a scalar reference
to the script. The sub is expected to process the script in-place. This is
one way to extend the HTML::Mason syntax with new tags, etc., although a much
more flexible way is to subclass the Lexer or Compiler class. See also
postprocess_text and postprocess_perl.
The class to use when creating requests. Defaults to
HTML::Mason::Request.
The class to use when creating a resolver. Defaults to
HTML::Mason::Resolver::File.
True or false, default is false. When false, Mason checks the
timestamp of the component source file each time the component is used
to see if it has changed. This provides the instant feedback for
source changes that is expected for development. However it does
entail a file stat for each component executed.
When true, Mason assumes that the component source tree is unchanging:
it will not check component source files to determine if the memory
cache or object file has expired. This can save many file stats per
request. However, in order to get Mason to recognize a component
source change, you must flush the memory cache and remove object files.
See static_source_touch_file for one easy way to arrange this.
We recommend turning this mode on in your production sites if
possible, if performance is of any concern.
Specifies a filename that Mason will check once at the beginning of
of every request. When the file timestamp changes, Mason will (1) clear
its in-memory component cache, and (2) remove object files if
they have not already been deleted by another process.
This provides a convenient way to implement static_source mode.
All you need to do is make sure that a single file gets touched
whenever components change. For Mason's part, checking a single
file at the beginning of a request is much cheaper than checking
every component file when static_source=0.
The class into which subcomponent objects are blessed. This defaults
to HTML::Mason::Component::Subcomponent.
True or false, default is true. Specifies whether Mason creates
object files to save the results of component parsing. You may want to
turn off object files for disk space reasons, but otherwise this
should be left alone.
True or false, default is true. Indicates whether component line
numbers that appear in error messages, stack traces, etc. are in terms
of the source file instead of the object file. Mason does this by
inserting '#line' directives into compiled components. While source
line numbers are more immediately helpful, object file line numbers
may be more appropriate for in-depth debugging sessions.
True or false, default is true. Indicates whether or not a given
component should use strict.
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