
term_string(?Term, ?String)

   Conversion between a Prolog term and a string.



Arguments
   ?Term               Prolog term.
   ?String             String or a variable.

Type
   Term Manipulation

Description
   If String is instantiated, its contents are parsed, and if the whole
   string can be parsed as one Prolog term it is unified with Term.  If
   String is not instantiated, Term is written into a string (using
   writeq/2) and String is bound to it.


   To change the way the term is converted into a string, e.g.  to include
   print metaterm handlers, it is possible to define it as follows:



term_to_string(T, S) :-
    open(string(""), write, Stream),
    % use the flags which you want
    printf(Stream, "%mw", [T]),
    get_stream_info(Stream, name, S),
    close(Stream).



Resatisfiable
      No.

Fail Conditions
      Fails if String is not the string conversion of the term Term.



Exceptions
     5 --- String is instantiated, but not to a string.
     7 --- String cannot be converted to a Prolog term.

Examples
   
Success:
      term_string(T, "look").      (gives T=look).
      term_string(T, "26.0").      (gives T=26.0).
      term_string(T, "f(1,2).").   (gives T=f(1,2)).
      term_string(T, "f(1,2)").    (gives T=f(1,2)).
      term_string(f(1,2),L).       (gives L="f(1, 2)").
      term_string(f(1,2),"f(1, 2)").
      term_string(atom,S).         (gives S="atom").
      term_string(.(a,.(1,[])),S). (gives S="[a, 1]").
      term_string(2.60,"2.6").
      term_string(2.6,"2.60").
      term_string(T,S).            (gives T=_g94; S="_g94").

Fail: term_string(2.6,"2.5").

Error:
      term_string(T,atom).              (Error 5).
      [eclipse]: term_string(T,"F(1,2)").  % String not a string
      F(1,2)                               % of a prolog term
       ^ (here?)
      syntax error: unexpected token
      string contains unexpected characters in term_string(T, "F(1,2)")





See Also
   integer_atom / 2, number_string / 2, string_list / 2, split_string / 4
