[ Obsolete | Reference Manual | Alphabetic Index ]

global ++SpecList

Declares the procedure(s) and other modular items specified by SpecList to be global.

SpecList: Sequence of modular item specifications.

This built-in predicate is obsolete!

Description

This predicate is obsolete - global visibility is being deprecated. For procedures, use export declarations instead. For other global items, replace them by local ones and, if necessary, provide exported access procedures to manipulate them.

This predicate was used to declare the visibility of procedures and other names as global. SpecList is a comma-separated list of expressions of the following form:

Name/Arity: procedure specification (since global procedures are no longer supported, this is now the same as exporting)
variable(Name): non-logical variable declaration
reference(Name): reference declaration
array(Name): untyped non-logical array declaration
array(Name,Type): typed non-logical array declaration
record(Name): record key declaration
struct(Prototype): structure declaration
op(Prec,Assoc,Name): operator declaration
macro(Functor,Transformation,Options): macro (input transformation) declaration
portray(Functor,Transformation,Options): portray (output transformation) declaration

For backward compatibility, global declarations of variables, references, arrays, records, structures, operators and macros still work. However, global procedure declarations now have the same effect as an export declaration and generate a warning message.

Modes and Determinism

global(++) is det

Modules

This predicate is sensitive to its module context (tool predicate, see @/2).

Exceptions

(4) instantiation fault: SpecList is not instantiated.
(5) type error: SpecList is instantiated, but not to a valid global specification
(94) trying to redefine an existing imported procedure: SpecList is already imported.

Examples

Success:

  [eclipse]: [user].
   :- global p/1.
   p(eclipse).
   user compiled 40 bytes in 0.00 seconds
  yes.
  [eclipse]: module(m).
  [m]: [user].
   :- local p/1. % can be omitted here since default is local.
   p(m).
   user compiled 40 bytes in 0.00 seconds
  yes.
  [m]: p(X).
  X = m
  yes.
  [m]: abolish(p/1).
  yes. % local predicate is abolished, global is visible again
  [m]: p(X).
  X = eclipse
  yes.

Error:

  global(Q).                        (Error 4).
  global("Pred").                   (Error 5).

  [eclipse]: [user].
   % :- tool(t/0) here would prevent error 62 in global(t/0) below
   p :- t.
   user   compiled 32 bytes in 0.02 seconds
  yes.
  [eclipse]: module(m).
  [m]: [user].
   :- tool(t/0, writeln/1).
   :- global(t/0).                  (Error 62).

  global(p/0), global(p/0).         (Error 89). (warning)
  (import p/0 from m), global(p/0). (Error 94).
  global(true/0).                   (Error 95).