Setting

As explained in Building User-Friendly DSLs

A value assigned on a language instance for a property from the concept it instantiates.

A setting assigns a value to a property on an instance of a concept. Settings give DSL content its concrete data and can also represent relations between instances. section 1.4.2 section 1.5

When an abstract syntax tree is encoded as JavaScript, settings follow these forms:

• Store settings as key-value pairs in an AST object's settings subobject. section 3.4
• Encode multivalued settings as arrays and navigate containment relations through their values. section 3.2.1 section 3.4
• Encode reference relations as objects whose ref property points to the target AST object. section 3.2.1 section 3.4

Reading and changing settings

For a rental record type, rental.settings["name"] reads the name setting, while rental.settings["attributes"][3] selects its fourth attribute. Updating rental.settings["attributes"][2].settings["initial value"].settings["value"] to 10 changes a nested setting. section 3.2.1

Figure 1.20 Zooming in on the structure aspect of a DSL

Use the structure diagram to connect concepts, properties, instances, and settings. section 1.4.2

How Building User-Friendly DSLs covers it

How deep it goes

Explains conceptual structure and JavaScript encoding, access, relation navigation, mutation, and traversal, without compiler internals.

Examples

Uses car-rental record types, attributes, arrays, reference objects, and nested initial-value updates.

What it assumes

Assumes basic concepts, properties, and instances while defining settings and their JavaScript representations in context.

What you can do after

Operate and modify encoded ASTs by reading settings, following relations, updating values, and traversing their structure.

How it connects

Connects concepts, properties, instances, relations, abstract syntax trees, containment relations, and reference relations.

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Related concepts

• edgeincludes · An edge is a graph connection between two vertices that represents a relationship and may be directed, labeled, or weighted.
• depth-first tree traversalused by · A tree traversal technique that visits a child subtree before later nodes at the same or higher level, then backtracks to continue.
• abstract syntax treepart of · An abstract syntax tree is a hierarchical tree representation of the syntactic structure of parsed source code or other language input, typically omitting superficial formatting details.
• constraintused by · A constraint is a condition or rule that restricts the permissible states, values, actions, or solutions in a system or problem.

This explainer was generated by Manning's knowledge graph from the text of Building User-Friendly DSLs. The section links point to the parts of the book it draws on.