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fic tell/1

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Vitor Santos Costa 2016-04-16 02:55:17 +01:00
parent 631eb4c265
commit 068b624fca
1 changed files with 45 additions and 8 deletions
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os/edio.yap
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@ -4,11 +4,11 @@
* @file edio.yap
* @author VITOR SANTOS COSTA <vsc@VITORs-MBP.lan>
* @date Wed Jan 20 01:07:02 2016
*
*
* @brief Input/Output according to the DEC-10 Prolog. PLease consider using the ISO
* standard predicates for new code.
*
*
*
*
*/
@ -76,7 +76,8 @@ If _S_ is a currently opened stream for output, it becomes the
current output stream. If _S_ is an atom it is taken to be a
filename. If there is no output stream currently associated with it,
then it is opened for output, and the new output stream created becomes
the current output stream. If it is not possible to open the file, an
the current output stream. Existing files are clobbered, use append/1 to extend a file.
If it is not possible to open the file, an
error occurs. If there is a single opened output stream currently
associated with the file, then it becomes the current output stream; if
there are more than one in that condition, one of them is chosen.
@ -103,9 +104,47 @@ tell(Stream) :-
current_stream(_,write,Stream), !,
set_output(Stream).
tell(F) :-
open(F,append,Stream),
open(F,write,Stream),
set_output(Stream).
/** @pred append(+ _S_)
If _S_ is a currently opened stream for output, it becomes the
current output stream. If _S_ is an atom it is taken to be a
filename. If there is no output stream currently associated with it,
then it is opened for output in *append* mode, that is, by adding new data to the end of the file.
The new output stream created becomes
the current output stream. If it is not possible to open the file, an
error occurs. If there is a single opened output stream currently
associated with the file, then it becomes the current output stream; if
there are more than one in that condition, one of them is chosen.
Whenever _S_ is a stream not currently opened for output, an error
may be reported, depending on the state of the file_errors flag. The
predicate just fails, if _S_ is neither a stream nor an atom.
*/
tell(user) :- !, set_output(user_output).
tell(F) :- var(F), !,
'$do_error'(instantiation_error,tell(F)).
tell(F) :-
current_output(Stream),
stream_property(Stream,file_name(F)),
!.
tell(F) :-
current_stream(_,write,Stream),
'$user_file_name'(Stream, F), !,
set_output(Stream).
tell(Stream) :-
'$stream'(Stream),
current_stream(_,write,Stream), !,
set_output(Stream).
tell(F) :-
open(F,write,Stream),
set_output(Stream).
/** @pred telling(- _S_)
@ -129,8 +168,6 @@ simultaneously opened streams is 17.
*/
told :- current_output(Stream),
flush_output(Stream),
!,
set_output(user),
set_output(user_output),
close(Stream).