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, 6 insertions, 7 deletions

diff --git a/lib.h b/lib.h
index 34c6b59d..9ebfe524 100644
--- a/lib.h
+++ b/lib.h
@@ -412,12 +412,13 @@ INLINE val chr(wchar_t ch)
 
 #define lit(strlit) lit_noex(strlit)
 
-#define keyword_package (deref(get_keyword_package()))
-#define user_package (deref(get_user_package()))
-#define system_package (deref(get_system_package()))
+#define keyword_package keyword_package_var
+#define user_package user_package_var
+#define system_package system_package_var
+#define cur_package (get_current_package())
 
 extern val system_package_var, keyword_package_var, user_package_var;
-extern val keyword_package_s, system_package_s, user_package_s;
+extern val package_s, keyword_package_s, system_package_s, user_package_s;
 extern val null_s, t, cons_s, str_s, chr_s, fixnum_sl;
 extern val sym_s, pkg_s, fun_s, vec_s;
 extern val stream_s, hash_s, hash_iter_s, lcons_s, lstr_s, cobj_s, cptr_s;
@@ -788,9 +789,7 @@ val symbolp(val sym);
 val symbol_name(val sym);
 val symbol_package(val sym);
 val keywordp(val sym);
-loc get_user_package(void);
-loc get_system_package(void);
-loc get_keyword_package(void);
+val get_current_package(void);
 val func_f0(val, val (*fun)(val env));
 val func_f1(val, val (*fun)(val env, val));
 val func_f2(val, val (*fun)(val env, val, val));