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 CWlowercase_with_underscores, while the Apache version uses CWStudlyCaps with a CWMason prefix. The conversion from one version to the other is otherwise very predictable. For example,

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CWautohandler_name CW<--> CWMasonAutohandlerName

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CWcomp_root CW<--> CWMasonCompRoot

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CWdata_cache_defaults CW<--> CWMasonDataCacheDefaults

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,

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In an custom wrapper-based configuraiton, you can pass most of these parameters to the ApacheHandler constructor.

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In a standalone Mason script, you can pass most of these parameters to the Interp constructor.

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When launching a subrequest, you can pass any of the CWHTML::Mason::Request parameters to make_subrequest.

* Perl name: allow_globals

* Apache name: MasonAllowGlobals

* Type in httpd.conf: list

* Default: []

List of variable names, complete with prefix (CW$@%), that you intend to use as globals in components. Normally global variables are forbidden by CWstrict, 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, CW$r (the request object) is automatically added to this list.

* Perl name: apache_status_title

* Apache name: MasonApacheStatusTitle

* Type in httpd.conf: string

* Default: HTML::Mason status

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.

* Perl name: args_method

* Apache name: MasonArgsMethod

* Type in httpd.conf: string

* Default: mod_perl

Method to use for unpacking GET and POST arguments. The valid options are 'CGI' and 'mod_perl'; these indicate that a CWCGI.pm or CWApache::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 CWApache::Request package. Under mod_perl-2, the default is 'CGI' because CWApache2::Request is still in development.

If args_method is 'mod_perl', the CW$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 CWApache::Request for more information.

If the args_method is 'CGI', the Mason request object (CW$m) will have a method called CWcgi_object available. This method returns the CGI object used for argument processing.

While Mason will load CWApache::Request or CWCGI 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.

* Perl name: auto_send_headers

* Apache name: MasonAutoSendHeaders

* Type in httpd.conf: boolean

* Default: 1

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 CW$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 CW$r->send_http_header is no longer needed.

* Perl name: autoflush

* Apache name: MasonAutoflush

* Type in httpd.conf: boolean

* Default: 0

True or false, default is false. Indicates whether to flush the output buffer (CW$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 CW$m->flush_buffer calls would work nearly as well.

* Perl name: autohandler_name

* Apache name: MasonAutohandlerName

* Type in httpd.conf: string

* Default: autohandler

File name used for autohandlers. Default is autohandler. If this is set to an empty string ("") then autohandlers are turned off entirely.

* Perl name: buffer_preallocate_size

* Apache name: MasonBufferPreallocateSize

* Type in httpd.conf: string

* Default: 0

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.

* Perl name: code_cache_max_size

* Apache name: MasonCodeCacheMaxSize

* Type in httpd.conf: string

* Default: unlimited

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.

* Perl name: comp_class

* Apache name: MasonCompClass

* Type in httpd.conf: string

* Default: HTML::Mason::Component

The class into which component objects are blessed. This defaults to HTML::Mason::Component.

* Perl name: comp_root

* Apache name: MasonCompRoot

* Type in httpd.conf: list

* Default: Varies

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 CWtitle() 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 CW$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.

* Perl name: compiler_class

* Apache name: MasonCompilerClass

* Type in httpd.conf: string

* Default: HTML::Mason::Compiler::ToObject

The class to use when creating a compiler. Defaults to HTML::Mason::Compiler.

* Perl name: data_cache_api

* Apache name: MasonDataCacheApi

* Type in httpd.conf: string

* Default: 1.1

The CW$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.

* Perl name: data_cache_defaults

* Apache name: MasonDataCacheDefaults

* Type in httpd.conf: hash_list

* Default: None

A hash reference of default options to use for the CW$m->cache command. For example, to use the CWMemoryCache implementation by default,

    data_cache_defaults => {cache_class => 'MemoryCache'}

These settings are overriden by options given to particular CW$m->cache calls.

* Perl name: data_dir

* Apache name: MasonDataDir

* Type in httpd.conf: string

* Default: None

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 CWMemoryCache instead of CWFileCache.

* Perl name: decline_dirs

* Apache name: MasonDeclineDirs

* Type in httpd.conf: boolean

* Default: 1

True or false, default is true. Indicates whether Mason should decline directory requests, leaving Apache to serve up a directory index or a CWFORBIDDEN error as appropriate. See the allowing directory requests section of the administrator's manual for more information about handling directories with Mason.

* Perl name: default_escape_flags

* Apache name: MasonDefaultEscapeFlags

* Type in httpd.conf: string

* Default: []

Escape flags to apply to all <% %> expressions by default. The current valid flags are

    h - escape for HTML ('<' => '&lt;', 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.

* Perl name: define_args_hash

* Apache name: MasonDefineArgsHash

* Type in httpd.conf: string

* Default: auto

One of always, auto, or never. This determines whether or not an CW%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.

* Perl name: dhandler_name

* Apache name: MasonDhandlerName

* Type in httpd.conf: string

* Default: dhandler

File name used for dhandlers. Default is dhandler. If this is set to an empty string ("") then dhandlers are turned off entirely.

* Perl name: dynamic_comp_root

* Apache name: MasonDynamicCompRoot

* Type in httpd.conf: boolean

* Default: 0

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.

* Perl name: enable_autoflush

* Apache name: MasonEnableAutoflush

* Type in httpd.conf: boolean

* Default: 1

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.

* Perl name: error_format

* Apache name: MasonErrorFormat

* Type in httpd.conf: string

* Default: Varies

Indicates how errors are formatted. The built-in choices are

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brief - just the error message with no trace information

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text - a multi-line text format

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line - a single-line text format, with different pieces of information separated by tabs (useful for log files)

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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 CWHTML::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 CWHTML::Mason::Exception::as_xml patterned after one of the built-in methods.

* Perl name: error_mode

* Apache name: MasonErrorMode

* Type in httpd.conf: string

* Default: Varies

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.

* Perl name: escape_flags

* Apache name: MasonEscapeFlags

* Type in httpd.conf: hash_list

* Default: None

A hash reference of escape flags to set for this object. See the section on the set_escape method for more details.

* Perl name: ignore_warnings_expr

* Apache name: MasonIgnoreWarningsExpr

* Type in httpd.conf: regex

* Default: qr/Subroutine .* redefined/i

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.

* Perl name: in_package

* Apache name: MasonInPackage

* Type in httpd.conf: string

* Default: HTML::Mason::Commands

This is the package in which a component's code is executed. For historical reasons, this defaults to CWHTML::Mason::Commands.

* Perl name: interp_class

* Apache name: MasonInterpClass

* Type in httpd.conf: string

* Default: HTML::Mason::Interp

The class to use when creating a interpreter. Defaults to HTML::Mason::Interp.

* Perl name: lexer_class

* Apache name: MasonLexerClass

* Type in httpd.conf: string

* Default: HTML::Mason::Lexer

The class to use when creating a lexer. Defaults to HTML::Mason::Lexer.

* Perl name: max_recurse

* Apache name: MasonMaxRecurse

* Type in httpd.conf: string

* Default: 32

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.

* Perl name: object_file_extension

* Apache name: MasonObjectFileExtension

* Type in httpd.conf: string

* Default: .obj

Extension to add to the end of object files. Default is .obj.

* Perl name: out_method

* Apache name: MasonOutMethod

* Type in httpd.conf: code

* Default: Print to STDOUT

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 CW$r->print.

* Perl name: plugins

* Apache name: MasonPlugins

* Type in httpd.conf: list

* Default: []

An array of plugins that will be called at various stages of request processing. Please see HTML::Mason::Plugin for details.

* Perl name: postamble

* Apache name: MasonPostamble

* Type in httpd.conf: string

* Default: None

Text given for this parameter is placed at the end of each component. See also preamble. The request will be available as CW$m in postamble code.

* Perl name: postprocess_perl

* Apache name: MasonPostprocessPerl

* Type in httpd.conf: code

* Default: None

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.

* Perl name: postprocess_text

* Apache name: MasonPostprocessText

* Type in httpd.conf: code

* Default: None

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.

* Perl name: preamble

* Apache name: MasonPreamble

* Type in httpd.conf: string

* Default: None

Text given for this parameter is placed at the beginning of each component, but after the execution of any CW<%once> block. See also postamble. The request will be available as CW$m in preamble code.

* Perl name: preloads

* Apache name: MasonPreloads

* Type in httpd.conf: list

* Default: None

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 CW<%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 CW$m or CW$r in a CW<%once> section will fail.

* Perl name: preprocess

* Apache name: MasonPreprocess

* Type in httpd.conf: code

* Default: None

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.

* Perl name: request_class

* Apache name: MasonRequestClass

* Type in httpd.conf: string

* Default: HTML::Mason::Request

The class to use when creating requests. Defaults to HTML::Mason::Request.

* Perl name: resolver_class

* Apache name: MasonResolverClass

* Type in httpd.conf: string

* Default: HTML::Mason::Resolver::File

The class to use when creating a resolver. Defaults to HTML::Mason::Resolver::File.

* Perl name: static_source

* Apache name: MasonStaticSource

* Type in httpd.conf: boolean

* Default: 0

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.

* Perl name: static_source_touch_file

* Apache name: MasonStaticSourceTouchFile

* Type in httpd.conf: string

* Default: None

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.

* Perl name: subcomp_class

* Apache name: MasonSubcompClass

* Type in httpd.conf: string

* Default: HTML::Mason::Component::Subcomponent

The class into which subcomponent objects are blessed. This defaults to HTML::Mason::Component::Subcomponent.

* Perl name: use_object_files

* Apache name: MasonUseObjectFiles

* Type in httpd.conf: boolean

* Default: 1

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.

* Perl name: use_source_line_numbers

* Apache name: MasonUseSourceLineNumbers

* Type in httpd.conf: boolean

* Default: 1

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.

* Perl name: use_strict

* Apache name: MasonUseStrict

* Type in httpd.conf: boolean

* Default: 1

True or false, default is true. Indicates whether or not a given component should CWuse strict.