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, 2 insertions, 0 deletions

diff --git a/eval.c b/eval.c
index c3392acd..e649af91 100644
--- a/eval.c
+++ b/eval.c
@@ -3398,6 +3398,7 @@ val load(val target)
 
   dyn_env = make_env(nil, nil, dyn_env);
   env_vbind(dyn_env, load_path_s, path);
+  env_vbind(dyn_env, package_s, cur_package);
 
   if (!read_eval_stream(stream, std_error, nil)) {
     close_stream(stream, nil);
@@ -5203,6 +5204,7 @@ void eval_init(void)
   reg_fun(intern(lit("make-sym"), user_package), func_n1(make_sym));
   reg_fun(intern(lit("gensym"), user_package), func_n1o(gensym, 0));
   reg_var(gensym_counter_s = intern(lit("*gensym-counter*"), user_package), zero);
+  reg_var(package_s = intern(lit("*package*"), user_package), user_package_var);
   reg_fun(intern(lit("make-package"), user_package), func_n1(make_package));
   reg_fun(intern(lit("find-package"), user_package), func_n1(find_package));
   reg_fun(intern(lit("delete-package"), user_package), func_n1(delete_package));