- SINGLE VS MULTIPLE WINDOWS
- THE %WindowInterface HASH
- SCRIPT HANDLERS
- WRITING PLUGINS
- AUTHOR & COPYRIGHT
- SEE ALSO
WWW::Scripter - For scripting web sites that have scripts
This is a subclass of WWW::Mechanize that uses the W3C DOM and provides support for scripting.
No actual scripting engines are provided with WWW::Scripter, but are available as separate plugins. (See also the "SEE ALSO" section below.)
SINGLE VS MULTIPLE WINDOWS
There are two basic modes in which you can use WWW::Scripter:
If you only need a single virtual window (which is usually the case), use WWW::Scripter itself, as described below and in WWW::Mechanize.
For multiple windows, start with a window group (see WWW::Scripter::WindowGroup) and fetch the WWW::Scripter object via its
active_window method before proceeding.
At any time you can attach an existing window (WWW::Scripter object) to a window group using the latter's
attach method. You can also
->close a window to detach it from its window group and put it back in single-window mode.
These two modes affect the behaviour of a few methods (
focus) and hyperlinks and forms with explicit targets.
In addition to those, this module implements the well-known Window interface, providing also a few routines for attaching scripting engines and what-not.
In the descriptions below,
$w refers to the WWW::Scripter object. You can think of it as short for either 'WWW::Scripter' or 'window'.
my $w = new WWW::Scripter %args
The constructor accepts named arguments. There are only two that WWW::Scripter itself deals with directly. The rest are passed on to the superclass. See WWW::Mechanize and LWP::UserAgent for details on what other arguments the constructor accepts.
The two arguments are:
The maximum number of document objects to keep in history (along with their corresponding request and response objects). If this is omitted, Mech's
stack_depth+ 1 will be used. This is off by one because
stack_depthis the number of pages you can go back to, so it is one less than the number of recorded pages.
max_docsconsiders 0 to be equivalent to infinity.
If the number of items in history exceeds
max_docs, WWW::Scripter will still keep the request objects (so you can go back more than
max_docstimes and previously visited pages will reload).
max_historyrestricts the total number of items in history (whether full document objects or just requests). 0 is equivalent to infinity.
The Window Interface
Returns the location object (see WWW::Scripter::Location). If you pass an argument, it sets the
hrefattribute of the location object.
Each of these calls the function assigned by one of the
set_*methods below under "Window-Related Methods".
Returns the navigator object. See WWW::Scripter::Navigator.
Returns the screen object. It currently has no features.
- setTimeout ( $code_string, $ms );
- setTimeout ( $coderef, $ms, @args );
This schedules the code to run after
$msmilliseconds have elapsed, returning a number uniquely identifying the time-out. If the first argument is a coderef or an object with
- setInterval ( $code_string, $ms );
- setInterval ( $coderef, $ms, @args );
This method is just like
setTimeout, except that, when the code runs, it schedules it to run again after
- clearTimeout ( $timeout_id )
The cancels the time-out corresponding to the
$timeout_id. This only works for those registered with
- clearInterval ( $timer_id )
The cancels the timer corresponding to the
$timer_id. This only works for those registered with
- open ( $url, $target, $features, $replace )
$targetis not specified or if there is no window or frame named
$target, this methods opens the
$urlin a new window in multiple-window mode, or at the top-level window in single-window mode.
If there is a window or frame named
$target, then the
$urlis opened in that window. If
$replaceis true, it replaces the current page.
$urlis resolved according to the base URL of the current window (the one that
openis called on), not the
$featuresargument is ignored.
In multiple-window mode, this detaches this window from its window group. In single-window mode (when there is no window group) it goes back to the previous entry in history (so that it is the opposite of
In multiple-window mode, this brings this window to the front. In single-window mode (when there is no window group) it does nothing.
In multiple-window mode, this sends this window back one, if it is the frontmost window. In single-window mode (when there is no window group) it does nothing.
Returns the history object. See WWW::Scripter::History.
These two return the window object itself.
Although the W3C DOM specifies that this return
$w(the window itself), for efficiency's sake this returns a separate object which one can use as a hash or array reference to access its sub-frames. (The window object itself cannot be used that way.) The frames object (class WWW::Scripter::Frames) also has a
windowmethod that returns
In list context a list of frames is returned.
Returns the number of frames.
$w->lengthis equivalent to
Returns the 'top' window, which is the window itself if there are no frames.
Returns the parent frame, if there is one, or the window object itself otherwise.
This returns the window's name, if applicable. For a frame, this comes from the frame element to which the window belongs. For a top-level window created by
open, this is the name that was passed as the second argument.
These exist in case scripts try to call them. They don't do anything.
These methods are not part of the Window interface, but are closely related to the object's window behaviour.
Use these to set the functions called by the above methods. There are no default
promptfunctions. The default
alertprints to the currently selected file handle, with a line break tacked on the end.
This evaluates the code associated with each timeout registered with the
setTimeoutmethod, if the appropriate interval has elapsed.
This returns the number of timers currently registered.
- wait_for_timers ( %args )
This method waits for any registered timers to finish (calling
check_timersrepeatedly in a loop). Its
%argsare as follows:
max_wait Number indicating for how many seconds the loop should run before giving up and returning. min_timers Only run until this many timers are left, not until they have all finished. interval Number of seconds to wait before each iteration of the loop. The default is .1.
Some websites have timers running constantly, that are never cleared. For these, you will usually need to set a value for
max_wait) to avoid an infinite loop.
This returns the window group that owns this window. See "SINGLE VS MULTIPLE WINDOWS", above.
You can also pass an argument to set it, but you should only do so if you know what you are doing, as it does not update the window group's list. Consider using WWW::Scripter::WindowGroup's
attachmethod (which itself uses this method).
- find_target ( $name )
This finds the WWW::Scripter object (window or frame) in which a link will be opened.
$nameis not an empty string, it returns the window corresponding to
$nameis the empty string or undefined, it returns the default target for this window, based on the first
If a named window cannot be found: in multiple-window mode, a new window is opened and returned; in single-window mode,
Methods for Fetching Images
- fetch_images ( $new_val )
A boolean indicating whether images should be fetched. Some sites use images with special URLs as cookies and refuse to work if those images are not fetched. Most of the time, however, you probably want to leave this off, for speed's sake.
Setting this does not affect any pages that are already loaded.
- image_handler ( $coderef )
A subroutine for handling any images that are fetched. The subroutine will be passed three arguments: 0) the WWW::Scripter object, 1) the image or input element and 2) the response object.
Methods for Plugins, Scripting, etc.
- eval ( $code [, $scripting_language] )
$codepassed to it. This method dies if there is no script handler registered for the
- use_plugin ( $plugin_name [, @options] )
This will automatically
require()the plugin for you, and then initialise it. To pass extra options to the plugin after loading it, just use the same syntax again. This will return the plugin object if the plugin has one.
- plugin ( $plugin_name )
This will return the plugin object, if it has one. Some plugins may provide this as a way to communicate directly with the plugin.
You can also use the return value as a boolean, to see whether a plugin is loaded.
- dom_enabled ( $new_val )
This returns a boolean indicating whether HTML pages are parsed and turned into a DOM tree. It is true by default. You can disable HTML parsing by passing a false value. Of course, if you are using WWW::Scripter to begin with, you won't want to turn this off will you? Nevertheless, this is useful for fetching files behind the scenes when just the file contents are needed.
- scripts_enabled ( $new_val )
This returns a boolean indicating whether scripts are enabled. It is true by default. You can disable scripts by passing a false value. When you disable scripts, event handlers are also disabled, as is the registration of event handlers by HTML event attributes.
- script_handler ( $language_re, $object )
A script handler is a special object that knows how to run scripts in a particular language. Use this method to register such an object.
$language_reis a regular expression that will be matched against a scripting language name (from a 'language' HTML attribute) or MIME type (<script type=...). You can also use the special value 'default'.
$objectis the script handler object. For its interface, see "SCRIPT HANDLERS", below.
- class_info ( \%interfaces )
With this you can provide information for binding Perl classes to scripting languages, so that scripts can handle objects of those classes.
You should pass a hash ref that has the structure described in HTML::DOM::Interface, except that this method also accepts a
_constructorhash element, which should be set to the name of the method to be called when the constructor function is called from the scripting language (e.g.,
_constructor => 'new') or a subroutine reference.
The return value is a list of all hashrefs passed to
class_infoso far plus a few that WWW::Scripter has by default (to support the DOM). You can call it without any arguments just to get that list.
The equivalent of hitting the 'forward' button in a browser. This, of course, only works after
- clear_history ( $including_current_page )
This clears the history, preventing
backfrom working until after the next request, and freeing up some memory. If supplied with a true argument, it also clears the current page. It returns
- max_history ( $new_value )
- max_docs ( $new_value )
These two return what was passed to the constructor, optionally setting it.
Notes About WWW::Mechanize Methods
WWW::Scripter overrides the
follow_linkuse behind the scenes, to make it use the HTML DOM tree instead of the source code of the page.
This overridden method tries hard to match WWW::Mechanize as closely as possible, which means it includes link tags, (i)frames, and meta tags with http-equiv set to 'refresh'.
This is significantly different from
$w->document->links, an HTML::DOM method that follows the W3C DOM spec and returns only 'a' and 'area' elements.
To trigger events (and event handlers), use the
trigger_event method of the object on which you want to trigger it. For instance:
$w->trigger_event('resize'); # runs onresize handlers $w->document->links->->trigger_event('mouseover'); $w->current_form->trigger_event('submit'); # same as $w->submit
WWW::Scripter does not implement any event loop, so you have to call
wait_for_timers yourself to trigger any timeouts. If you set up a loop like this,
sleep 1, $w->check_timers while $w->count_timers;
or if you use
wait_for_timers, beware that these may cause an infinite loop if a timeout sets another timeout, or if a timer is registered with
setInterval. You basically have to know what works with the pages you are browsing.
The hash named
%WWW::Scripter::WindowInterface lists the interface members for the window object. It follows the same format as hashes within %HTML::DOM::Interface, like this:
( alert => VOID|METHOD, confirm => BOOL|METHOD, ... )
It only includes those methods listed above under "The Window Interface".
This section is only of interest to those implementing scripting engines. If you are not writing one, skip this section (or just read it anyway).
A script handler object must provide the following methods:
- eval ( $w, $code, $url, $line, $is_inline )
$wis the WWW::Scripter object)
This is supposed to run the
$codepassed to it. It must set
$@to a true value if there is an error.
- event2sub ( $w, $elem, $event_name, $code, $url, $line )
This is called for each HTML event attribute (onclick, etc.). It should return a coderef that runs the
If it could not create a code ref, it should return
undefand put the error message, if any, in
Plugins are usually under the WWW::Scripter::Plugin:: namespace. If a plugin name has a hyphen (-) in it, the module name will contain a double colon (::). If, when you pass a plugin name to
plugin, it has a double colon in its name, it will be treated as a fully-qualified module name (possibly) outside the usual plugin namespace. Here are some examples:
Plugin Name Module Name ----------- ----------- Chef WWW::Scripter::Plugin::Chef Man-Page WWW::Scripter::Plugin::Man::Page My::Odd::Plugin My::Odd::Plugin
This module will need to have an
init method, and possibly two more named
initwill be called as a class method the first time
use_pluginis called for a particular plugin. The second argument (
$_) will be the WWW::Scripter object. The third argument will be an array ref of options (see "options", below).
It may return an object if the plugin has one.
$w->use_pluginis called, if there are any arguments after the plugin name, then the plugin object's
optionsmethod will be called with the options themselves as the arguments.
If a plugin does not provide an object, an error will be thrown if options are passed to
initmethod can override this, however. When it is called, its third argument is a reference to an array containing the options passed to
use_plugin. The contents of that same array will be used when
optionsis called, so
initcan modify it and even prevent
optionsfrom being called altogether, by emptying the array.
When the WWW::Scripter object is cloned (via the
clonemethod), every plugin that has a clone method (as determined by
->can('clone')), will also be cloned. The new clone of the WWW::Scripter object is passed as its argument.
If the plugin needs to record data pertinent to the current page, it can do so by associating them with the document or the request via a field hash. See Hash::Util::FieldHash and Hash::Util::FieldHash::Compat.
See LWP's Handlers feature.
From within LWP's
response_* handlers, you can call
WWW::Scripter will export this function upon request:
use WWW::Scripter qw[ abort ];
or you can call it with a fully qualified name:
This is still an unfinished work. There are probably scores of bugs crawling all over the place. Here are some that are known (apart from the fact that so many features are still missing):
There is no support for XHTML, but HTML::Parser can handle most XHTML pages anyway, so maybe this is not a problem.
There is nothing to prevent infinite recursion when frames have circular references.
perl 5.8.3 or higher (5.8.4 or higher recommended)
HTML::DOM 0.045 or higher
LWP 5.77 or higher
WWW::Mechanize 1.2 or higher
Tie::RefHash::Weak 0.08 or higher for perl 5.8.x.
AUTHOR & COPYRIGHT
Copyright (C) 2009-16, Father Chrysostomos (sprout at, um, cpan dot org)
This program is free software; you may redistribute or modify it (or both) under the same terms as perl.
Some of the code in here was stolen from the immediate superclass, WWW::Mechanize, as were some of the tests and test data.
See WWW::Mechanize, of which this is a subclass.
See also the following plugins:
And, if you are curious, have a look at the plugin version of WWW::Mechanize and WWW::Mechanize::Plugin::DOM (experimental and now deprecated) that this was originally based on: http://www-mechanize.googlecode.com/svn/wm/branches/plugins/