logtalk_load_context/2¶

Description¶

logtalk_load_context(Key, Value)

Provides access to the Logtalk compilation/loading context. The following keys are currently supported:

entity_identifier - identifier of the entity being compiled if any
entity_prefix - internal prefix for the entity compiled code
entity_type - returns the value module when compiling a module as an object
source - full path of the source file being compiled
file - the actual file being compiled, different from source only when processing an include/1 directive
basename - source file basename
directory - source file directory
stream - input stream being used to read source file terms
target - the full path of the intermediate Prolog file
flags - the list of the explicit flags used for the compilation of the source file
term - the source file term being compiled
term_position - the position of the term being compiled (StartLine-EndLine)
variable_names - the variable names of the term being compiled ([Name1=Variable1, ...])

The logtalk_load_context/2 predicate can also be called initialization/1 directives in a source file. A common scenario is to use the directory key to define library aliases.

Warning

The term_position key is only supported in backend Prolog compilers that provide access to the start and end lines of a read term.

Currently, any variables in the values of the term and variable_names keys are not shared with, respectively, the term and goal arguments of the term_expansion/2 and goal_expansion/2 methods.

Using the variable_names key requires calling the standard built-in predicate term_variables/2 on the term read and unifying the term variables with the variables in the names list. This, however, may rise portability issues with those Prolog compilers that don’t return the variables in the same order for the term_variables/2 predicate and the option variable_names/1 of the read_term/3 built-in predicate, which is used by the Logtalk compiler to read source files.

Modes and number of proofs¶

logtalk_load_context(?atom, -nonvar) - zero_or_more

Errors¶

(none)

Examples¶

term_expansion(Term, ExpandedTerms) :-
    ...
    logtalk_load_context(entity_identifier, Entity),
    ....

:- initialization((
    logtalk_load_context(directory, Directory),
    assertz(logtalk_library_path(my_app, Directory))
)).