existence_error/2

Description

existence_error(Thing, Culprit)

Throws an existence error. Used when the subject of an operation does not exist. This built-in method is declared private and thus cannot be used as a message to an object. Calling this predicate is equivalent to the following sequence of goals:

...,
context(Context),
throw(error(existence_error(Thing,Culprit), Context)).

This allows the user to generate errors in the same format used by the runtime.

Possible values for Thing include:

  • predicate_declaration
  • procedure
  • source_sink
  • stream
  • object
  • protocol
  • category
  • module
  • library
  • file
  • goal_thread

The value of Culprit is the argument or one of its sub-terms that caused the error.

Modes and number of proofs

existence_error(@nonvar, @nonvar) - error

Errors

When called:
existence_error(Thing, Culprit)