13.12.3 Other Changes

• The atom length restriction has been lifted.
• The Emacs command run-prolog now prompts for a (Lisp) list of extra command line arguments, when invoked with a prefix argument, i.e. as C-U M-x run-prolog.
• While loading clauses from a PO file, if clauses for an existing multifile predicate are encountered, but in a precompiled format different from the existing clauses, then the existing clauses remain untouched, the multifile clauses from the PO file are simply ignored, the load continues, and a permission error is raised at the end. Previously, the existing clauses would silently be replaced by the loaded ones. This feature is mainly relevant for hook predicates such as user:term_expansion/6.
• “System Properties” has been introduced as an abstraction to replace the direct use of environment variables. See System Properties and Environment Variables in the SICStus Prolog Manual for more information.

  The change is largely backwards compatible with the following notable exceptions:

  • The environment variables SP_APP_DIR, SP_RT_DIR, etc. are no longer set in the environment. This means that their value can no longer be obtained, e.g. from C code, by using getenv() or similar functions. Instead, SP_getenv() can be used for a similar effect.
  • For the same reason, sub-processes created with process:process_create/[2,3] will no longer see SP_APP_DIR et al. in their inherited environment. Instead it is now possible to explicitly pass environment variables to the sub-process using the new environment/1 option to process:process_create/3.
• New automatically set system properties, SP_APP_PATH, the path to the executable, SP_RT_DIR, the path to the SICStus runtime, and SP_STARTUP_DIR the initial working directory. See System Properties and Environment Variables in the SICStus Prolog Manual for more information.
• The initial working directory can be set with the system property SP_STARTUP_DIR, independently from the process’s working directory. By setting the system property SP_ALLOW_CHDIR to ‘no’, SICStus can be told to never change the process’s working directory. These features are especially useful when embedding SICStus.
• The buffer argument to spio_t_simple_device_write is now a void const* instead of a plain void *. This affects code that use SP_create_stream() to create user-defined streams.
• SP_get_list_n_bytes() and SP_get_list_n_codes() now use stricter input validation.
• SICStus will no longer flush open streams on exit. This change is to prevent SICStus from hanging on exit due to some blocking I/O operation. All streams should be explicitly closed (close/[1,2]) or flushed (flush_output/1) if their contents is precious.
• clpfd:case/4: the leaves/2 option has been dropped, and the variable order must be the same on every path.
• library(system): library(system) no longer depends on any foreign code so the system foreign resource is gone.
• library(jasper): The SICStus (Java) working directory is now passed to Java (SICStus) when Java (SICStus) is started from SICStus (Java). Also, SICStus will not change the process’s working directory when started from Java.
• The Berkeley DB library, library(bdb), is now built using Berkeley DB 4.8.24.