options — The Logtalk Handbook v3.47.0 documentation

# `options`

This library provides useful predicates for managing developer tool and application options.

## API documentation

Open the ../../docs/library_index.html#options file in a web browser.

## Loading

To load all entities in this library, load the `loader.lgt` utility file:

    | ?- logtalk_load(options(loader)).

## Testing

To test this library predicates, load the `tester.lgt` file:

    | ?- logtalk_load(options(tester)).

## Usage

The `options` category is usually imported by the root object of the developer tool or application. The importing object should define the `default_option/1` predicate and, if option type-checking is required, the `valid_option/1` predicate. This library requires options to be represented by compound terms but leaves otherwise to the clients the actual representation.

The library also supports a user-defined `fix_option/2` predicate. An usage example is when an option value can be a relative file path that should be expanded before used. Another usage example would be converting from a user-friendly option to a form more suitable for internal processing. When a call to the `fix_option/2` predicate fails, the option is used as-is.