Language Specification

Grammar

Language Specification

Concepts

Objects

However, there is one way in which Bento objects are unique. In Bento, all objects are considered data; they may contain logic, but this logic is not directly visible to a user of the object. All the user sees is the data generated by the logic.

Because Bento objects are data, not logic, Bento objects do not have callable functions in the conventional sense. The only methods in Bento are constructors.

This is a feature, not a flaw. Bento is capable of performing any computation or implementing any algorithm, but the logic must be properly encapsulated. This up front architectural cost is minor compared to the increased reliability and ease of maintenance which is achieved.

Processors

A Bento site is defined in one or more Bento files, which generally have a ".bento" extension. The Bento processor reads these files and builds an internal representation of their contents. This representation is then used to generate pages.

Elements

Comments

Comments may appear anywhere except inside static blocks or quoted strings. Comments may be nested.

Statements

• A directive provides information and structions to the Bento processor, such as linkage information for external objects.
• A definition specifies how an object is constructed.
• A construction generates data for an object.

Contained in the site and core definitions are object definitions, which may in turn contain more definitions. Object definitions may also contain constructions, which are the Bento statements that actually build the object.

Blocks

    [|
        <table border="1" bgcolor="#DDDDDD" cellpadding="16">
            <tr><td>This HTML code is inside of a static block.</td></tr>
        </table>
    |]

                

A dynamic block is delimited by the special character pairs [= and =] and contains Bento statements. Here is a dynamic block containing three Bento statements:

    [=
        prologue;
        story;
        epilogue;
    =]

                

Static blocks may have embedded dynamic blocks and vice versa. Here is the same dynamic block as above, but with three static blocks embedded in it:

    [=
        [| <h2>Prologue</h2> |]
        prologue;

        [| <h2>The Story</h2> |]
        story;

        [| <h2>Epilogue</h2> |]
        epilogue;
    =]

                

    [|
        <h2>Prologue</h2>
        [= prologue; =]

        <h2>The Story</h2>
        [= story; =]

        <h2>Epilogue</h2>
        [= epilogue; =]
    |]

                

Directives

Definitions

• top-level definitions, either site or core statements. They contain definitions that are global within a site or among all sites, respectively.

• object definitions, which contain the logic and data for constructing an object. Object definitions can optionally be typed, specify parameters or both.

• array definitions, which specify arrays of objects. Arrays can either be fixed in size or growable, and either typed or untyped.

The following example consists of a site definition containing a typed, unparamaterized object definition, which itself contains an untyped array definition.

    site simple_site [=

        page foo [=

            itemlist[] = [ "item 1", "item 2", "item 3" ]

        =]
    =]

                

Constructions

• anonymous constructions, consisting of unnamed static or dynamic blocks.

• named constructions, which instantiate specific objects.
• conditional constructions, which execute blocks if specified conditions hold true.
• iterated constructions, which execute blocks for all the members of a group, or until a specified condition holds true.
• sub and super constructions, which execute the constructions in the current object's subclass or superclass.

The following example consists of an object definition containing a number of different kinds of constructions, along with an object definition.

    thingamabob [=

        /* an anonymous construction */
        [| <h3> |]

        /* a conditional construction */
        if (label) [=

            /* a named construction */
            label;

        =] else [|
             (Untitled)
        |]

        /* another anonymous construction */
        [| </h3> |]

        /* sub construction */
        sub;

        /* abstract object definition */
        label [?]
    =]

                

Names

Types

Parameters

Grammar for the Bento Language