| Template Attribute Language |
Article Index for Template |
Website Links For Template |
Information AboutTemplate Attribute Language |
| CATEGORIES ABOUT TEMPLATE ATTRIBUTE LANGUAGE | |
| zope | |
| template engines | |
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TAL was created for Zope but is used in other Python -based projects as well. OVERVIEW TAL Templates are often made from result pages with the variable content being replaced by special attributes; e.g., would be treated by a common HTML design tool as while the application server, evaluating the tal:content attribute, would yield Of course, String Literals are not the most common nor the most useful use case; the syntax of the possible attribute values is property of the TAL Expression Syntax ( TALES ) language. In the Python -based implementations, it is e.g. possible to use Python expressions. Using METAL (Macro Expansion TAL) it is possible to re-use code from other templates. When generating XML documents, it is important to specify the XML namespace xmlns:tal="http://xml.zope.org/namespaces/tal"ATTRIBUTES The following attributes are used, normally prefixed by „tal:“: ; define : creates local variables, valid in the Element bearing the attribute (including contained elements) ; condition : decides whether or not to render the tag (and all contained text) ; repeat : creates a loop variable and repeats the tag iterating a sequence, e.g. for creating a selection list or a table ; content : replaces the content of the tag ; replace : replaces the tag (and therefore is not usable together with content or attributes) ; attributes : replaces the given attributes (e. g. by using tal:attributes="name name; id name" the name and id attributes of an input field could be set to the value of the Variable „name“); omit-tag : allows to omit the start and end tag and only render the content if the given expression is true. ; on-error : if an error occurs, this attribute works like the content tag. If a tag has more than one TAL attributes, they are evaluated in the above (fairly logical) order. In cases when no tag is present which lends itself to take the attributes, special TAL tags can be used, making the „tal:“ prefix optional. E. g., would cause the code inside the tal:if tags to be used whenever the context (whatever the application server defines the context to be, e.g. an object) contains variable „itemlist“ with a ''true'' value, e.g. a list containing at least one element. The identifier following the colon is arbitrary; it simply needs to be there, and to be the same for the opening and closing tag.USAGE TAL/ TALES / METAL are used by the following projects:
OTHER IMPLEMENTATIONS Besides the original Zope implementation, there are (not exhaustive): Python
Java
Perl
PHP XSL
EXTERNAL LINKS
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