Templates

A template is a pattern with slots to be filled in.

• A stencil serves as a physical example of a template.
• A "form" with spaces to be filled in serves as a paper example.
• An HTML form entity is a software analogue.
• A simple type of template which connects software and hardware is an optically scanned "bubble sheet".

In computer language recognition, one can apply templates in two modes:

• recognition:

  - discovery of entities in the template;

  - interpretation of these entities

  - interpretation might include interactions between entities

• generation:

  - generate a legal "instance" of the template

  - this usually means the instance should have particular semantics

  Terms:

  • attribute — a property of an entity
  • attribute value — the value of an instance of that entity

  In a "classical" template system, attributes are determined by their location in relation to some "base datum".

  • A clear example of this is the "bubble sheet".
  • Discuss how in a particular browser window, at a particular time, an HTML form exhibits the same characteristic, viz., that attributes depend on explicit locations.

  In recognition mode, the computer determines what the attribute is from where it occurs in the "pattern" currently being examined. It "reads" the attribute's value at this location.

  (In the "bubble-sheet" example, the value is yes/no, depending on whether the bubble is blackened or not. In the HTML form example, the value is text that has been filled in by the user.)

  In generation mode, the computer "somehow" assigns a value to the attribute.

  A simple example of this is when a user signs in to an on-line site. The login mechanism retrieve the user's profile elements and puts the contents into a form for display.