Implement *package* special var; package overhaul.

* eval.c (load): Rebind *package* in the local dynamic
environment already established for the sake of *load-path*.
By doing this we cause *package* to be restored to its
prior value, which allows the loaded file to alter it.
Common Lisp works this way.
(eval_init): Register *package* variable, with the
user package as its default value.

* lib.c (package_s): New symbol variable.
(intern, rehome_sym): Default the package argument to the
current package, not to user_package.
(get_user_package, get_system_package, get_keyword_package):
Functions removed.
(get_current_package): New function.
(obj_print_impl): Revise symbol printing. Keyword and
uninterned symbols are printed with : and #: prefixes.
The remainder are printed with a package prefix if their
home package isn't the current package.

* lib.h (keyword_package, user_package, system_package): These
macros are just straight aliases for the global
variables, not going through the lookup mechanism,
which was pointless.
(cur_package): New macro.
(package_s): Declared.
(get_current_package): Declared.

* lisplib.c (lisplib_try_load): Establish a local
dynamic environment, and bind the *package* variable
to the user package which the library modules expect.

* parser.c (find_matching_syms, provide_completions):
Treat unqualified symbols in the current package
rather than user package.

* parser.y (sym_helper): Intern unqualified symbols
in the current package, not user package.

* txr.1: Document that the variables user-package,
system-package and keyword-package should not be modified.
Document the *package* special variable, and that intern and
rehome-sym default their package argument to its value. (Here
we get rid of wrong references to the undocumented variable
*user-package*).

1 files changed, 11 insertions, 26 deletions

diff --git a/lib.c b/lib.c
index 8f1ca8c4..21901c7f 100644
--- a/lib.c
+++ b/lib.c
@@ -79,7 +79,7 @@ int async_sig_enabled = 0;
 val packages;
 
 val system_package_var, keyword_package_var, user_package_var;
-val system_package_s, keyword_package_s, user_package_s;
+val package_s, system_package_s, keyword_package_s, user_package_s;
 
 val null_s, t, cons_s, str_s, chr_s, fixnum_s, sym_s, pkg_s, fun_s, vec_s;
 val lit_s, stream_s, hash_s, hash_iter_s, lcons_s, lstr_s, cobj_s, cptr_s;
@@ -4832,7 +4832,7 @@ val intern(val str, val package)
   loc place;
 
   if (null_or_missing_p(package)) {
-    package = user_package;
+    package = cur_package;
   } else if (stringp(package)) {
     val p = find_package(package);
     if (!p)
@@ -4859,7 +4859,7 @@ val rehome_sym(val sym, val package)
     return nil;
 
   if (null_or_missing_p(package)) {
-    package = user_package;
+    package = cur_package;
   } else if (stringp(package)) {
     val p = find_package(package);
     if (!p)
@@ -4893,25 +4893,9 @@ val keywordp(val sym)
   return tnil(sym && symbolp(sym) && sym->s.package == keyword_package_var);
 }
 
-loc get_user_package(void)
+val get_current_package(void)
 {
-  if (nilp(user_package_s))
-    return mkcloc(user_package_var);
-  return lookup_global_var_l(user_package_s);
-}
-
-loc get_system_package(void)
-{
-  if (nilp(system_package_s))
-    return mkcloc(system_package_var);
-  return lookup_global_var_l(system_package_s);
-}
-
-loc get_keyword_package(void)
-{
-  if (nilp(keyword_package_s))
-    return mkcloc(keyword_package_var);
-  return lookup_global_var_l(keyword_package_s);
+  return cdr(lookup_var(nil, package_s));
 }
 
 val func_f0(val env, val (*fun)(val))
@@ -9435,11 +9419,12 @@ dot:
     break;
   case SYM:
     if (!pretty) {
-      if (obj->s.package != user_package) {
-        if (!obj->s.package)
-          put_char(chr('#'), out);
-        else if (obj->s.package != keyword_package)
-          put_string(obj->s.package->pk.name, out);
+      if (!obj->s.package) {
+        put_string(lit("#:"), out);
+      } else if (obj->s.package == keyword_package) {
+        put_char(chr(':'), out);
+      } else if (obj->s.package != cur_package) {
+        put_string(obj->s.package->pk.name, out);
         put_char(chr(':'), out);
       }
     }