This document lists all available selectors of @doctitle@ and - describes their purpose.
++ This document lists all available selectors of @doctitle@ and + describes their purpose. +
Forthcoming... -
+
+ Selectors in @docname@ have a role similar to matchers
+ while being more flexible. Like matchers they are designed
+ to test something against a part of the environment (the
+ request URI, headers, cookies and so on), but unlike matchers
+ they can be active decision driving components.
+ A matcher allows only for simple
+ "yes/no" decisions: the match can be succesful or not, if it
+ is the pipeline is executed, if not it's simply ignored.
+ Selectors go a step further allowing for more complex
+ use cases, where there is need for a decision to be
+ made according to a multiple chance scenario. In short you can
+ think of matchers as an "if" statement, while selectors have all
+ the power of an "if-else if-else" or "switch-case" construct.
+ The selector syntax is similar will be familiar to people
+ using the XSLT <xsl:test> statement.
+
+ As an example consider the typical scenario where a page has to + be rendered in different way according to the browser being + used. There are plenty of browsers out there so expressing this + need as a set of matchers might become ankward and counterintuitive. + Using the BrowserSelector, which checks a given pattern + against the user-agent header, it's easy to deploy a consistent + and readable setup: +
+Forthcoming... -
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