HTML::Mason::Interp - Mason Component Interpreter
my $i = HTML::Mason::Interp->new (data_dir=>'/usr/local/mason',
comp_root=>'/usr/local/www/htdocs/',
...other params...);
Interp is the Mason workhorse, executing components and routing their output and errors to all the right places. In a mod_perl environment, Interp objects are handed off immediately to an ApacheHandler object which internally calls the Interp implementation methods. In that case the only user method is the new() constructor.
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 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 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.
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.
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.
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.
All of the above properties have standard accessor methods of the same name. Only comp_root and ignore_warnings_expr can be modified in an existing interpreter; the rest are read-only.
This method applies a one or more escapes to a piece of text. The escapes are specified by giving their flag. Each escape is applied to the text in turn, after which the now-modified text is returned.
Given an escape name, this removes that escape from the interpreter's known escapes. If the name is not recognized, it is simply ignored.
This method is called to add an escape flag to the list of known
escapes for the interpreter. The flag may only consist of the
characters matching \w and the dash (-). It must start with an
alpha character or an underscore (_).
The right hand side may be one of several things. It can be a
subroutine reference. It can also be a string match /^\w+$/, in
which case it is assumed to be the name of a subroutine in the
HTML::Mason::Escapes module. Finally, if it is a string that does
not match the above regex, then it is assumed to be evalable code,
which will return a subroutine reference.
When setting these with PerlSetVar directives in an Apache
configuration file, you can set them like this:
PerlSetVar MasonEscapeFlags "h => \&HTML::Mason::Escapes::basic_html_escape"
PerlSetVar MasonEscapeFlags "flag => \&subroutine"
PerlSetVar MasonEscapeFlags "uc => sub { ${$_[0]} = uc ${$_[0]}; }"
PerlAddVar MasonEscapeFlags "thing => other_thing"
Given an absolute component path, this method returns a boolean value indicating whether or not a component exists for that path.
Creates a new HTML::Mason::Request object for the given comp and args, and executes it. The return value is the return value of comp, if any.
This is useful for running Mason outside of a web environment. See HTML::Mason::Admin/using Mason from a standalone script for examples.
This method isn't generally useful in a mod_perl environment; see subrequests instead.
Empties the component cache. When using Perl 5.00503 or earlier, you should call this when finished with an interpreter, in order to remove circular references that would prevent the interpreter from being destroyed.
Returns the component object corresponding to an absolute component
path, or undef if none exists. Dies with an error if the component
fails to load because of a syntax error.
This method compiles Mason component source code and returns a
Component object. The source may be passed in as a string in comp_source,
or as a filename in comp_file. When using comp_file, the
filename is specified as a path on the file system, not as a path
relative to Mason's component root (see
$m->fetch_comp for that).
If Mason encounters an error during processing, an exception will be thrown.
Example of usage:
# Make an anonymous component
my $anon_comp =
eval { $interp->make_component
( comp_source => '<%perl>my $name = "World";</%perl>Hello <% $name %>!' ) };
die $@ if $@;
$m->comp($anon_comp);
This method creates a Mason request object. The arguments to be passed
are the same as those for the HTML::Mason::Request->new
constructor or its relevant subclass. This method will likely only be
of interest to those attempting to write new handlers or to subclass
HTML::Mason::Interp. If you want to create a subrequest, see
subrequests instead.
Called during request execution in order to clear out the code cache. Mainly useful to subclasses that may want to take some custom action upon clearing the cache.
This method sets a global to be used in components. varname is a
variable name, optionally preceded with a prefix ($, @, or
%); if the prefix is omitted then $ is assumed. varname is
followed by a value, in the case of a scalar, or by one or more values
in the case of a list or hash. For example:
# Set a global variable $dbh containing the database handle
$interp->set_global(dbh => DBI->connect(...));
# Set a global hash %session from a local hash
$interp->set_global('%session', %s);
The global is set in the package that components run in: usually
HTML::Mason::Commands, although this can be overridden via the
in_package parameter.
The lines above, for example, are equivalent to:
$HTML::Mason::Commands::dbh = DBI->connect(...);
%HTML::Mason::Commands::session = %s;
assuming that in_package has not been changed.
Any global that you set should also be registered with the
allow_globals parameter; otherwise you'll get warnings from
strict.