Feature #462: autoload with a block

• Status: Rejected
• Assignee: matz (Yukihiro Matsumoto)
• Target version: -

[nobu (Nobuyoshi Nakada)]

=begin
Hi,

At Mon, 18 Aug 2008 10:35:01 +0900,
Nobuyoshi Nakada wrote in [ruby-talk:311603]:

At Fri, 15 Aug 2008 15:57:21 +0900,
David Masover wrote in [ruby-talk:311365]:

autoload :Foo do
require 'foo'
Foo.autoload :Bar ...
end

In that simplest form, it would at least centralize all my loading stuff in
one place. In a more meta form, I could run through some search paths I'm
likely to use (in my own app, for instance), and generate an autoload scheme
based on that.

I don't think it makes things simpler, but it sounds
interesting. You can file it in the ITS, if you want.
http://redmine.ruby-lang.org/projects/ruby/issues?set_filter=1&tracker_id=2

Although the OP doesn't seem to intend to request this feature,
I move it to ruby-core since it feels interesting.

Index: load.c

--- load.c (revision 18653)
+++ load.c (working copy)
@@ -618,10 +618,29 @@ ruby_init_ext(const char *name, void (*i

static VALUE
-rb_mod_autoload(VALUE mod, VALUE sym, VALUE file)
+rb_mod_autoload(int argc, VALUE *argv, VALUE mod)
{

• ID id = rb_to_id(sym);
• Check_SafeStr(file);
• rb_autoload(mod, id, RSTRING_PTR(file));

• extern VALUE rb_autoload_proc(VALUE, ID, VALUE, VALUE);
• ID id;
• VALUE block = rb_block_given_p() ? rb_block_proc() : Qnil;
• VALUE arg = Qnil;
• switch (argc) {

•  case 2:
  

• arg = argv[1];
• break;

•  case 1:
  

• if (!NIL_P(block)) break;

•  default:
  

• rb_raise(rb_eArgError, "wrong number of arguments (%d for 2)", argc);
• }
• id = rb_to_id(argv[0]);
• if (NIL_P(block)) {
• VALUE file = argv[1];
• Check_SafeStr(file);
• rb_autoload(mod, id, RSTRING_PTR(file));
• }
• else {
• rb_autoload_proc(mod, id, block, arg);
• }
  return Qnil;
  }
  @@ -649,5 +668,5 @@ rb_mod_autoload_p(VALUE mod, VALUE sym)

static VALUE
-rb_f_autoload(VALUE obj, VALUE sym, VALUE file)
+rb_f_autoload(int argc, VALUE *argv, VALUE obj)
{
VALUE klass = rb_vm_cbase();
@@ -655,5 +674,5 @@ rb_f_autoload(VALUE obj, VALUE sym, VALU
rb_raise(rb_eTypeError, "Can not set autoload on singleton class");
}

• return rb_mod_autoload(klass, sym, file);

• return rb_mod_autoload(argc, argv, klass);
  }

@@ -693,7 +712,7 @@ Init_load()
rb_define_global_function("load", rb_f_load, -1);
rb_define_global_function("require", rb_f_require, 1);

• rb_define_method(rb_cModule, "autoload", rb_mod_autoload, 2);

• rb_define_method(rb_cModule, "autoload", rb_mod_autoload, -1);
  rb_define_method(rb_cModule, "autoload?", rb_mod_autoload_p, 1);

• rb_define_global_function("autoload", rb_f_autoload, 2);

• rb_define_global_function("autoload", rb_f_autoload, -1);
  rb_define_global_function("autoload?", rb_f_autoload_p, 1);

Index: variable.c

--- variable.c (revision 18653)
+++ variable.c (working copy)
@@ -1322,16 +1322,12 @@ check_autoload_table(VALUE av)
}

-void
-rb_autoload(VALUE mod, ID id, const char *file)
+typedef VALUE rb_autoload_func(VALUE, ID, VALUE, VALUE);
+
+static void
+autoload_callback(VALUE mod, ID id, rb_autoload_func *func, VALUE arg1, VALUE arg2)
{

• VALUE av, fn;

• VALUE av;
  struct st_table *tbl;

• if (!rb_is_const_id(id)) {
• rb_raise(rb_eNameError, "autoload must be constant name: %s", rb_id2name(id));
• }
• if (!file || !*file) {
• rb_raise(rb_eArgError, "empty file name");
• }

• NODE *n;

  if ((tbl = RCLASS_IV_TBL(mod)) && st_lookup(tbl, id, &av) && av != Qundef)
  @@ -1348,8 +1344,61 @@ rb_autoload(VALUE mod, ID id, const char
  DATA_PTR(av) = tbl = st_init_numtable();
  }

• n = rb_node_newnode(NODE_MEMO, (VALUE)func, arg1, arg2);

• st_insert(tbl, id, (st_data_t)n);
  +}

+static VALUE
+autoload_load(VALUE klass, ID id, VALUE file, VALUE safe)
+{

• return rb_require_safe(file, (int)safe);
  +}

+static void
+check_autoload_id(ID id)
+{

• if (!rb_is_const_id(id)) {
• rb_raise(rb_eNameError, "autoload must be constant name: %s", rb_id2name(id));
• }
  +}

+void
+rb_autoload(VALUE mod, ID id, const char *file)
+{

• VALUE fn;
• check_autoload_id(id);
• if (!file || !*file) {
• rb_raise(rb_eArgError, "empty file name");
• }
• fn = rb_str_new2(file);
  FL_UNSET(fn, FL_TAINT);
  OBJ_FREEZE(fn);

• st_insert(tbl, id, (st_data_t)rb_node_newnode(NODE_MEMO, fn, rb_safe_level(), 0));

• autoload_callback(mod, id, autoload_load, fn, (VALUE)rb_safe_level());
  +}

+void
+rb_autoload_callback(VALUE mod, ID id, rb_autoload_func *func, VALUE arg1, VALUE arg2)
+{

• check_autoload_id(id);
• autoload_callback(mod, id, func, arg1, arg2);
  +}

+static VALUE
+autoload_proc_call(VALUE mod, ID id, VALUE proc, VALUE arg)
+{

• VALUE args[3];
• args[0] = mod;
• args[1] = ID2SYM(id);
• args[2] = arg;
• return rb_proc_call_with_block(proc, 3, args, Qnil);
  +}

+void
+rb_autoload_proc(VALUE mod, ID id, VALUE proc, VALUE arg)
+{

• rb_autoload_callback(mod, id, autoload_proc_call, proc, arg);
  }

@@ -1382,25 +1431,34 @@ VALUE
rb_autoload_load(VALUE klass, ID id)
{

• VALUE file;
  NODE *load = autoload_delete(klass, id);

• if (!load || !(file = load->nd_lit)) {

• if (!load) {
  return Qfalse;
  }

• return rb_require_safe(file, load->nd_nth);

• return load->u1.cfunc(klass, id, load->u2.value, load->u3.value);
  }

static VALUE
-autoload_file(VALUE mod, ID id)
+autoload_p(VALUE mod, ID id)
{
VALUE val, file;
struct st_table *tbl;

• st_data_t load;

• st_data_t data;
• NODE *load;

• if (!st_lookup(RCLASS_IV_TBL(mod), autoload, &val) ||
• !(tbl = check_autoload_table(val)) || !st_lookup(tbl, id, &load)) {

• if (!st_lookup(RCLASS_IV_TBL(mod), autoload, &data) ||
• !(tbl = check_autoload_table(val = (VALUE)data)) ||
• !st_lookup(tbl, id, &data)) {
  return Qnil;
  }

• file = ((NODE *)load)->nd_lit;

• load = (NODE *)data;
• if (load->u1.cfunc == autoload_proc_call) {
• /* rb_obj_is_proc() */
• return load->u2.value;
• }
• if (load->u1.cfunc != autoload_load) {
• return Qtrue;
• }
• file = load->u2.value;
  Check_Type(file, T_STRING);
  if (!RSTRING_PTR(file) || !*RSTRING_PTR(file)) {
  @@ -1433,5 +1491,5 @@ rb_autoload_p(VALUE mod, ID id)
  return Qnil;
  }

• return autoload_file(mod, id);

• return autoload_p(mod, id);
  }

@@ -1630,5 +1688,5 @@ rb_const_defined_0(VALUE klass, ID id, i
while (tmp) {
if (RCLASS_IV_TBL(tmp) && st_lookup(RCLASS_IV_TBL(tmp), id, &value)) {

•  if (value == Qundef && NIL_P(autoload_file(klass, id)))
  

•  if (value == Qundef && NIL_P(autoload_p(klass, id)))
   return Qfalse;
   return Qtrue;
  

--
Nobu Nakada
=end

[ko1 (Koichi Sasada)]

• Assignee set to matz (Yukihiro Matsumoto)

=begin

=end

[matz (Yukihiro Matsumoto)]

• Status changed from Open to Rejected

=begin
the code in the block may not be executed (if the constant is defined anywhere else), so it is not stable.
=end