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The Caboteria / TWiki Web / TWikiDotPm (11 Apr 2011, TWikiContributor)

Package TWiki

TWiki operates by creating a singleton object (known as the Session object) that acts as a point of reference for all the different modules in the system. This package is the class for this singleton, and also contains the vast bulk of the basic constants and the per- site configuration mechanisms.

Global variables are avoided wherever possible to avoid problems with CGI accelerators such as mod_perl.

Public Data members

On this page:

StaticMethod getTWikiLibDir () -> $path

Returns the full path of the directory containing TWiki.pm

ObjectMethod UTF82SiteCharSet ($utf8) -> $ascii

Auto-detect UTF-8 vs. site charset in string, and convert UTF-8 into site charset.

ObjectMethod writeCompletePage ($text,$pageType,$contentType)

Write a complete HTML page with basic header to the browser.

This method removes noautolink and nop tags before outputting the page unless $contentType is text/plain.

ObjectMethod generateHTTPHeaders ($pageType,$contentType,$contentLength) -> $header

All parameters are optional.

Implements the post-Dec2001 release plugin API, which requires the writeHeaderHandler in plugin to return a string of HTTP headers, CR/LF delimited. Filters any illegal headers. Plugin headers will override core settings.

Does not add a Content-length header.

StaticMethod isRedirectSafe ($redirect)=>$ok

tests if the $redirect is an external URL, returning false if AllowRedirectUrl is denied

ObjectMethod redirect ($url,$passthrough,$action_redirectto)

Redirects the request to $url, unless

  1. It is overridden by a plugin declaring a redirectCgiQueryHandler.
  2. $session->{request} is undef or
  3. $query->param('noredirect') is set to a true value.
Thus a redirect is only generated when in a CGI context.

Normally this method will ignore parameters to the current query. Sometimes, for example when redirecting to a login page during authentication (and then again from the login page to the original requested URL), you want to make sure all parameters are passed on, and for this $passthrough should be set to true. In this case it will pass all parameters that were passed to the current query on to the redirect target. If the request_method for the current query was GET, then all parameters will be passed by encoding them in the URL (after ?). If the request_method was POST, then there is a risk the URL would be too big for the receiver, so it caches the form data and passes over a cache reference in the redirect GET.

NOTE: Passthrough is only meaningful if the redirect target is on the same server.

ObjectMethod cacheQuery () -> $queryString

Caches the current query in the params cache, and returns a rewritten query string for the cache to be picked up again on the other side of a redirect.

We can't encode post params into a redirect, because they may exceed the size of the GET request. So we cache the params, and reload them when the redirect target is reached.

StaticMethod isValidWikiWord ($name) -> $boolean

Check for a valid WikiWord or WikiName

StaticMethod isValidTopicName ($name) -> $boolean

Check for a valid topic name

StaticMethod isValidAbbrev ($name) -> $boolean

Check for a valid ABBREV (acronym)

StaticMethod isValidWebName ($name,$system) -> $boolean

STATIC Check for a valid web name. If $system is true, then system web names are considered valid (names starting with _) otherwise only user web names are valid

If $TWiki::cfg{EnableHierarchicalWebs} is off, it will also return false when a nested web name is passed to it.

ObjectMethod readOnlyMirrorWeb ($theWeb) -> ($mirrorSiteName,$mirrorViewURL,$mirrorLink,$mirrorNote)

If this is a mirrored web, return information about the mirror. The info is returned in a quadruple:

site name URL link note

ObjectMethod getSkin () -> $string

Get the currently requested skin path

ObjectMethod getScriptUrl ($absolute,$script,$web,$topic,...) -> $scriptURL

Returns the URL to a TWiki script, providing the web and topic as "path info" parameters. The result looks something like this: "http://host/twiki/bin/$script/$web/$topic".

If $absolute is set, generates an absolute URL. $absolute is advisory only; TWiki can decide to generate absolute URLs (for example when run from the command-line) even when relative URLs have been requested.

The default script url is taken from {ScriptUrlPath}, unless there is an exception defined for the given script in {ScriptUrlPaths}. Both {ScriptUrlPath} and {ScriptUrlPaths} may be absolute or relative URIs. If they are absolute, then they will always generate absolute URLs. if they are relative, then they will be converted to absolute when required (e.g. when running from the command line, or when generating rss). If $script is not given, absolute URLs will always be generated.

If either the web or the topic is defined, will generate a full url (including web and topic). Otherwise will generate only up to the script name. An undefined web will default to the main web name.

ObjectMethod getPubUrl ($absolute,$web,$topic,$attachment) -> $url

Composes a pub url. If $absolute is set, returns an absolute URL. If $absolute is set, generates an absolute URL. $absolute is advisory only; TWiki can decide to generate absolute URLs (for example when run from the command-line) even when relative URLs have been requested.

$web, $topic and $attachment are optional. A partial URL path will be generated if one or all is not given.

ObjectMethod cacheIconData ($action)

Cache icon data based on action:

ObjectMethod formatIcon ($iconName,$format,$default) -> $icon

Format an icon based on name and format parameter. The format parameter handles these variables (with example):

The optional default parameter specifies the icon name in case the icon is not defined. Leave empty if you assume icon files exist in the default location.

ObjectMethod normalizeWebTopicName ($theWeb,$theTopic) -> ($theWeb,$theTopic)

Normalize a Web.TopicName

See TWikiFuncDotPm for a full specification of the expansion (not duplicated here)

WARNING if there is no web specification (in the web or topic parameters) the web defaults to $TWiki::cfg{UsersWebName}. If there is no topic specification, or the topic is '0', the topic defaults to the web home topic name.

ClassMethod new ($loginName,$query,\%initialContext)

Constructs a new TWiki object. Parameters are taken from the query object.

ObjectMethod renderer ()

Get a reference to the renderer object. Done lazily because not everyone needs the renderer.

ObjectMethod attach ()

Get a reference to the attach object. Done lazily because not everyone needs the attach.

ObjectMethod templates ()

Get a reference to the templates object. Done lazily because not everyone needs the templates.

ObjectMethod i18n ()

Get a reference to the i18n object. Done lazily because not everyone needs the i18ner.

ObjectMethod search ()

Get a reference to the search object. Done lazily because not everyone needs the searcher.

ObjectMethod security ()

Get a reference to the security object. Done lazily because not everyone needs the security.

ObjectMethod net ()

Get a reference to the net object. Done lazily because not everyone needs the net.

ObjectMethod finish ()

Break circular references.

ObjectMethod writeLog ($action,$webTopic,$extra,$user)

Write the log for an event to the logfile

ObjectMethod writeWarning ($text)

Prints date, time, and contents $text to $TWiki::cfg{WarningFileName}, typically 'warnings.txt'. Use for warnings and errors that may require admin intervention. Use this for defensive programming warnings (e.g. assertions).

ObjectMethod writeDebug ($text)

Prints date, time, and contents of $text to $TWiki::cfg{DebugFileName}, typically 'debug.txt'. Use for debugging messages.

StaticMethod applyPatternToIncludedText ($text,$pattern) -> $text

Apply a pattern on included text to extract a subset

ObjectMethod inlineAlert ($template,$def,...) -> $string

Format an error for inline inclusion in rendered output. The message string is obtained from the template 'oops'.$template, and the DEF $def is selected. The parameters (...) are used to populate %PARAM1%..%PARAMn%

StaticMethod parseSections ($text) -> ($string,$sectionlistref)

Generic parser for sections within a topic. Sections are delimited by STARTSECTION and ENDSECTION, which may be nested, overlapped or otherwise abused. The parser builds an array of sections, which is ordered by the order of the STARTSECTION within the topic. It also removes all the SECTION tags from the text, and returns the text and the array of sections.

Each section is a TWiki::Attrs object, which contains the attributes {type, name, start, end} where start and end are character offsets in the string after all section tags have been removed. All sections are required to be uniquely named; if a section is unnamed, it will be given a generated name. Sections may overlap or nest.

See test/unit/Fn_SECTION.pm for detailed testcases that round out the spec.

ObjectMethod expandVariablesOnTopicCreation ($text,$user,$web,$topic) -> $text

Expand limited set of variables during topic creation. These are variables expected in templates that must be statically expanded in new content.

# SMELL: no plugin handler

StaticMethod entityEncode ($text,$extras) -> $encodedText

Escape special characters to HTML numeric entities. This is not a generic encoding, it is tuned specifically for use in TWiki.

HTML4.0 spec: "Certain characters in HTML are reserved for use as markup and must be escaped to appear literally. The "<" character may be represented with an entity, &lt;. Similarly, ">" is escaped as &gt;, and "&" is escaped as &amp;. If an attribute value contains a double quotation mark and is delimited by double quotation marks, then the quote should be escaped as &quot;.

Other entities exist for special characters that cannot easily be entered with some keyboards..."

This method encodes HTML special and any non-printable ascii characters (except for \n and \r) using numeric entities.

FURTHER this method also encodes characters that are special in TWiki meta-language.

$extras is an optional param that may be used to include additional characters in the set of encoded characters. It should be a string containing the additional chars.

StaticMethod entityDecode ($encodedText) -> $text

Decodes all numeric entities (e.g. &#123;). Does not decode named entities such as &amp; (use HTML::Entities for that)

StaticMethod urlEncodeAttachment ($text)

For attachments, URL-encode specially to 'freeze' any characters >127 in the site charset (e.g. ISO-8859-1 or KOI8-R), by doing URL encoding into native charset ($siteCharset) - used when generating attachment URLs, to enable the web server to serve attachments, including images, directly.

This encoding is required to handle the cases of:

- browsers that generate UTF-8 URLs automatically from site charset URLs - now quite common - web servers that directly serve attachments, using the site charset for filenames, and cannot convert UTF-8 URLs into site charset filenames

The aim is to prevent the browser from converting a site charset URL in the web page to a UTF-8 URL, which is the default. Hence we 'freeze' the URL into the site character set through URL encoding.

In two cases, no URL encoding is needed: For EBCDIC mainframes, we assume that site charset URLs will be translated (outbound and inbound) by the web server to/from an EBCDIC character set. For sites running in UTF-8, there's no need for TWiki to do anything since all URLs and attachment filenames are already in UTF-8.

StaticMethod urlEncode ($string) -> encodedstring

Encode by converting characters that are illegal in URLs to their %NN equivalents. This method is used for encoding strings that must be embedded verbatim in URLs; it cannot be applied to URLs themselves, as it escapes reserved characters such as = and ?.

RFC 1738, Dec. '94: 

    ...Only alphanumerics [0-9a-zA-Z], the special
    characters $-_.+!*'(), and reserved characters used for their
    reserved purposes may be used unencoded within a URL.

Reserved characters are $&+,/:;=?@ - these are also encoded by this method.

This URL-encoding handles all character encodings including ISO-8859-*, KOI8-R, EUC-* and UTF-8.

This may not handle EBCDIC properly, as it generates an EBCDIC URL-encoded URL, but mainframe web servers seem to translate this outbound before it hits browser - see CGI::Util::escape for another approach.

StaticMethod urlDecode ($string) -> decodedstring

Reverses the encoding done in urlEncode.

StaticMethod isTrue ($value,$default) -> $boolean

Returns 1 if $value is true, and 0 otherwise. "true" means set to something with a Perl true value, with the special cases that "off", "false" and "no" (case insensitive) are forced to false. Leading and trailing spaces in $value are ignored.

If the value is undef, then $default is returned. If $default is not specified it is taken as 0.

StaticMethod spaceOutWikiWord ($word,$sep) -> $string

Spaces out a wiki word by inserting a string (default: one space) between each word component. With parameter $sep any string may be used as separator between the word components; if $sep is undefined it defaults to a space.

ObjectMethod expandAllTags (\$text,$topic,$web,$meta)

Expands variables by replacing the variables with their values. Some example variables: %TOPIC%, %SCRIPTURL%, %WIKINAME%, etc. $web and $incs are passed in for recursive include expansion. They can safely be undef. The rules for tag expansion are:
  1. Tags are expanded left to right, in the order they are encountered.
  2. Tags are recursively expanded as soon as they are encountered - the algorithm is inherently single-pass
  3. A tag is not "encountered" until the matching }% has been seen, by which time all tags in parameters will have been expanded
  4. Tag expansions that create new tags recursively are limited to a set number of hierarchical levels of expansion

ObjectMethod enterContext ($id,$val)

Add the context id $id into the set of active contexts. The $val can be anything you like, but should always evaluate to boolean TRUE.

An example of the use of contexts is in the use of tag expansion. The commonTagsHandler in plugins is called every time tags need to be expanded, and the context of that expansion is signalled by the expanding module using a context id. So the forms module adds the context id "form" before invoking common tags expansion.

Contexts are not just useful for tag expansion; they are also relevant when rendering.

Contexts are intended for use mainly by plugins. Core modules can use $session->inContext( $id ) to determine if a context is active.

ObjectMethod leaveContext ($id)

Remove the context id $id from the set of active contexts. (see enterContext for more information on contexts)

ObjectMethod inContext ($id)

Return the value for the given context id (see enterContext for more information on contexts)

StaticMethod registerTagHandler ($tag,$fnref)

STATIC Add a tag handler to the function tag handlers.

StaticMethod registerRESTHandler ($subject,$verb,\&fn)

Adds a function to the dispatch table of the REST interface for a given subject. See TWikiScripts#rest for more info.

The handler function must be of the form: 

sub handler(\%session,$subject,$verb) -> $text
where:

Since: TWiki::Plugins::VERSION 1.1

ObjectMethod handleCommonTags ($text,$web,$topic,$meta) -> $text

Processes %VARIABLE%, and %TOC% syntax; also includes 'commonTagsHandler' plugin hook.

Returns the text of the topic, after file inclusion, variable substitution, table-of-contents generation, and any plugin changes from commonTagsHandler.

$meta may be undef when, for example, expanding templates, or one-off strings at a time when meta isn't available.

ObjectMethod ADDTOHEAD ($args)

Add $html to the HEAD tag of the page currently being generated.

Note that TWiki variables may be used in the HEAD. They will be expanded according to normal variable expansion rules.

%ADDTOHEAD%

You can write == in a topic or template. This variable accepts the following parameters: %ADDTOHEAD% expands in-place to the empty string, unless there is an error in which case the variable expands to an error string.

Use %RENDERHEAD% to generate the sorted head tags.

%<nop}RENDERHEAD%

... should be written where you want the sorted head tags to be generated. This will normally be in a template. The variable expands to a sorted list of the head blocks added up to the point the RENDERHEAD variable is expanded. Each expanded head block is preceded by an HTML comment that records the ID of the head block.

Head blocks are sorted to satisfy all their requires constraints. The output order of blocks with no requires value is undefined. If cycles exist in the dependency order, the cycles will be broken but the resulting order of blocks in the cycle is undefined.

StaticMethod initialize ($pathInfo,$remoteUser,$topic,$url,$query) -> ($topicName,$webName,$scriptUrlPath,$userName,$dataDir)

Return value: ( $topicName, $webName, $TWiki::cfg{ScriptUrlPath}, $userName, $TWiki::cfg{DataDir} )

Static method to construct a new singleton session instance. It creates a new TWiki and sets the Plugins $SESSION variable to point to it, so that TWiki::Func methods will work.

This method is DEPRECATED but is maintained for script compatibility.

Note that $theUrl, if specified, must be identical to $query->url()

StaticMethod readFile ($filename) -> $text

Returns the entire contents of the given file, which can be specified in any format acceptable to the Perl open() function. Fast, but inherently unsafe.

WARNING: Never, ever use this for accessing topics or attachments! Use the Store API for that. This is for global control files only, and should be used only if there is absolutely no alternative.

StaticMethod expandStandardEscapes ($str) -> $unescapedStr

Expands standard escapes used in parameter values to block evaluation. The following escapes are handled:

Escape: Expands To:
$n or $n() New line. Use $n() if followed by alphanumeric character, e.g. write Foo$n()Bar instead of Foo$nBar
$nop or $nop() Is a "no operation".
$quot Double quote (")
$percnt Percent sign (%)
$dollar Dollar sign ($)
$lt Less than sign (<)
$gt Greater than sign (>)

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