Logtalk reference manual
Built-in predicate: logtalk_library_path/2
Contents > Reference Manual > Built-in Predicates > logtalk_library_path/2

## logtalk_library_path/2

#### Description

    logtalk_library_path(Library, Path)

Dynamic and multifile user-defined predicate, allowing the declaration of aliases to library paths. Library aliases may also be used on the second argument (using the notation alias(path)). Paths must always end with the path directory separator character ('/').

Relative paths (e.g. `'../'` or `'./'`) should only be used within the alias(path)) notation so that library paths can always be expanded to absolute paths independently of the (usually unpredictable) current directory at the time the `logtalk_library_path/2` predicate is called.

When working with a relocatable application, the actual application installation directory can be retrieved by calling the `logtalk_load_context/2` predicate with the `directory` key and using the returned value to define the `logtalk_library_path/2` predicate. On a settings file, simply use an `initialization/1` directive to wrap the call to the `logtalk_load_context/2` predicate and the assert of the `logtalk_library_path/2` fact.

#### Template and modes

    logtalk_library_path(?atom, -atom)
    logtalk_library_path(?atom, -compound)

#### Errors

`(none)`

#### Examples

    | ?- logtalk_library_path(viewpoints, Path).

    Path = examples('viewpoints/')
    yes

    | ?- logtalk_library_path(Library, Path).

    Library = home,
    Path = '$HOME/' ;

    Library = logtalk_home,
    Path = '$LOGTALKHOME/' ;

    Library = logtalk_user
    Path = '$LOGTALKUSER/' ;

    Library = examples
    Path = logtalk_user('examples/') ;

    Library = library
    Path = logtalk_user('library/') ;

    Library = viewpoints
    Path = examples('viewpoints/')
    yes