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=== Engines using Value Substitution ===

The simplest form of templating engine is that which merely substitutes values into a template in order to produce the final output.

    * [http://docs.python.org/lib/node109.html string.Template] in the standard library
    * [http://www.stringtemplate.org stringtemplate] - employs recursion in order to provide support for complicated templating whilst avoiding side-effects
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A popular approach with templating engines is to embed logic or control-flow statements into the templates themselves in a way that can make the templates visually rather different from the final output, as well as introducing problems for some XML-based tools. Nevertheless, such templating engines may be more applicable to non-Web templating problems or for situations where separating logic from content may actually make the solution harder to understand. A popular approach with templating engines is to embed logic or control-flow statements into the templates themselves in a way that can make the the final output appear rather different from the original template. For example:

{{{
<table>
  <%
  for item in items:
    %>
    <tr>
      <th>Name</th>
      <td><%= item.name %></td>
    </tr>
    <%
  %>
</table>
}}}

The introduction of such logic may also cause problems for some XML-based tools. Despite these shortcomings, such templating engines may be more applicable to non-Web templating problems or for situations where separating logic from content may actually make the solution harder to understand.
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    * [http://www.stringtemplate.org stringtemplate]
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The following engines feature template documents whose sections are marked using special attributes (or, less frequently, special elements or tags). In some systems, the sections are then manipulated within program code: The following engines feature template documents whose sections are marked using special attributes (or, less frequently, special elements or tags). For example:

{{{
<table annotation:element="items">
  <tr annotation:element="item">
    <th>Name</th>
    <td>{name}</td>
  </tr>
</table>
}}}

In some systems, the sections are then manipulated within program code; in others, the template structure indicates sections which are to be repeated, omitted, and so on, and the templating system then merges the template with some data structure provided by the program. Generally, the reason for annotating templates in this way (particularly through the use of attributes) is to better support the editing of such templates in XML-based tools which might otherwise complain about or damage template information if it were not included carefully in documents.
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    * [http://psilib.sf.net/webstring.html webstring] uses ID attributes for markers
    * [http://www.python.org/pypi/XSLTools XSLTools] - uses special attributes (with XML documents providing the data)
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    * [http://genshi.edgewall.org/ Genshi] - Template engine inspired by Kid, supports both [http://genshi.edgewall.org/wiki/Documentation/xml-templates.html XML] and [http://genshi.edgewall.org/wiki/Documentation/text-templates.html plain-text] templates
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    * [http://kid.lesscode.org/ Kid] - XML based, compiling template engine     * [http://www.kid-templating.org/ Kid] - XML based, compiling template engine
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    * [http://cherrytemplate.python-hosting.com/ CherryTemplate]
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   * [http://genshi.edgewall.org/ Genshi] The genshi.builder module provides [http://genshi.edgewall.org/wiki/Documentation/builder.html simple markup generation]

Templating in Python

Templating, and in particular Web templating, involves the presentation of information in a form which is often (but not always) intended to be readable, even attractive, to a human audience. Frequently, templating solutions involve a document (the template) which may look somewhat like the final output but perhaps in a simplified or stylized form, along with some data which must be presented using that template; combining these two things produces the final output which in Web templating is usually (but not always) a Web page of some kind.

Templating Engines

There are many, many different HTML/XML templating packages and modules for Python that provide different feature sets and syntaxes. These libraries usually assume that you know how to write HTML or XML.

The number of templating engines is so great because the mechanisms involved are pretty easy to write in Python, at least for a fairly basic template engine; [http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52305 this recipe from the Python Cookbook] shows how easy it is.

Engines using Value Substitution

The simplest form of templating engine is that which merely substitutes values into a template in order to produce the final output.

Engines Mixing Logic into Templates

A popular approach with templating engines is to embed logic or control-flow statements into the templates themselves in a way that can make the the final output appear rather different from the original template. For example: 

<table>
  <%
  for item in items:
    %>
    <tr>
      <th>Name</th>
      <td><%= item.name %></td>
    </tr>
    <%
  %>
</table>

The introduction of such logic may also cause problems for some XML-based tools. Despite these shortcomings, such templating engines may be more applicable to non-Web templating problems or for situations where separating logic from content may actually make the solution harder to understand.

Engines with Annotated Templates

The following engines feature template documents whose sections are marked using special attributes (or, less frequently, special elements or tags). For example: 

<table annotation:element="items">
  <tr annotation:element="item">
    <th>Name</th>
    <td>{name}</td>
  </tr>
</table>

In some systems, the sections are then manipulated within program code; in others, the template structure indicates sections which are to be repeated, omitted, and so on, and the templating system then merges the template with some data structure provided by the program. Generally, the reason for annotating templates in this way (particularly through the use of attributes) is to better support the editing of such templates in XML-based tools which might otherwise complain about or damage template information if it were not included carefully in documents.

In other systems, the annotations are actually evaluated in order to produce repeated sections to omit or to include sections, and so on:

HTML Shorthand Processors

The libraries in this section implement simpler markup languages that can be automatically converted to HTML. This lets you avoid having to write HTML by hand.

HTML Generation Packages

These packages are not really templating systems in that they do not typically employ a template document as such to define the form of the output they produce, but they can be useful in applications where it is more convenient to programmatically generate output.

Static Website Generators

Static website generators are more than templating engines in that they create the whole site structure, not just individual files. While templating is an important part of their function, determining the site structure and incorporating structural information in the output (for example to automatically generate navigational elements) is what really makes a static website generator a useful tool.

Java Templating Engines

The following templating engines are accessible or usable via Jython:

CPython-accessible C Templating Engines

Templating (last edited 2019-12-15 07:18:08 by FrancesHocutt)

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