From: Nobuyoshi Nakada <nobu@...>
Date: 2008-11-14T15:09:52+09:00
Subject: [ruby-core:19927] Re: {Proc,Method}#parameters (Re: Proposal: Method#get_args)

Hi,

At Thu, 13 Nov 2008 18:44:53 +0900,
Brian Candler wrote in [ruby-core:19915]:
> That does give me an idea. Since "?" is not legal in a variable name, then a
> very simple option could be
> 
>    def foo(a, b, c=123, d=nil, *e, &blk)
> 
>      => ["a", "b", "?c", "?d", "*e", "&blk"]

It's simplest.

>    define_method(:bar) { |a,(b,c)|    }
> 
>      => ["a", ["b", "c"]]

Is it really necessary?


Index: iseq.c
===================================================================
--- iseq.c	(revision 20232)
+++ iseq.c	(working copy)
@@ -1275,4 +1275,44 @@ rb_iseq_clone(VALUE iseqval, VALUE newcb
 }
 
+VALUE
+rb_iseq_parameters(const rb_iseq_t *iseq)
+{
+    int i, r;
+    VALUE a, n, args = rb_ary_new2(iseq->arg_size);
+
+    for (i = 0; i < iseq->argc; i++) {
+	a = rb_id2str(iseq->local_table[i]);
+	rb_ary_push(args, a ? a : Qnil);
+    }
+    r = iseq->arg_rest != -1 ? iseq->arg_rest :
+	iseq->arg_post_len > 0 ? iseq->arg_post_start :
+	iseq->arg_block != -1 ? iseq->arg_block :
+	iseq->arg_size;
+    for (; i < r; i++) {
+	a = rb_id2str(iseq->local_table[i]);
+	n = rb_str_new2("?");
+	if (a) rb_str_append(n, a);
+	rb_ary_push(args, n);
+    }
+    if (iseq->arg_rest != -1) {
+	a = rb_id2str(iseq->local_table[iseq->arg_rest]);
+	n = rb_str_new2("*");
+	if (a) rb_str_append(n, a);
+	rb_ary_push(args, n);
+    }
+    r = iseq->arg_post_start + iseq->arg_post_len;
+    for (i = iseq->arg_post_start; i < r; i++) {
+	a = rb_id2str(iseq->local_table[i]);
+	rb_ary_push(args, a ? a : Qnil);
+    }
+    if (iseq->arg_block != -1) {
+	a = rb_id2str(iseq->local_table[iseq->arg_block]);
+	n = rb_str_new2("&");
+	if (a) rb_str_append(n, a);
+	rb_ary_push(args, n);
+    }
+    return args;
+}
+
 /* ruby2cext */
 
Index: proc.c
===================================================================
--- proc.c	(revision 20232)
+++ proc.c	(working copy)
@@ -26,7 +26,10 @@ VALUE rb_cBinding;
 VALUE rb_cProc;
 
+VALUE rb_iseq_parameters(const rb_iseq_t *iseq);
+
 static VALUE bmcall(VALUE, VALUE);
 static int method_arity(VALUE);
 static VALUE rb_obj_is_method(VALUE m);
+static rb_iseq_t *get_method_iseq(VALUE method);
 
 /* Proc */
@@ -616,6 +619,12 @@ get_proc_iseq(VALUE self)
     GetProcPtr(self, proc);
     iseq = proc->block.iseq;
-    if (!RUBY_VM_NORMAL_ISEQ_P(iseq))
-	return 0;
+    if (!RUBY_VM_NORMAL_ISEQ_P(iseq)) {
+	NODE *node = (NODE *)iseq;
+	iseq = 0;
+	if (nd_type(node) == NODE_IFUNC && node->nd_cfnc == bmcall) {
+	    /* method(:foo).to_proc */
+	    iseq = get_method_iseq(node->nd_tval);
+	}
+    }
     return iseq;
 }
@@ -651,4 +660,34 @@ rb_proc_location(VALUE self)
 }
 
+static VALUE
+unnamed_parameters(int arity)
+{
+    VALUE param = rb_ary_new2((arity < 0) ? -arity : arity);
+    if (arity < 0) {
+	rb_ary_store(param, ~arity, rb_str_new2("*"));
+    }
+    else {
+	rb_ary_store(param, arity-1, Qnil);
+    }
+    return param;
+}
+
+/*
+ * call-seq:
+ *    proc.parameters  => array
+ *
+ * returns the parameter information of this proc
+ */
+
+static VALUE
+rb_proc_parameters(VALUE self)
+{
+    rb_iseq_t *iseq = get_proc_iseq(self);
+    if (!iseq) {
+	return unnamed_parameters(proc_arity(self));
+    }
+    return rb_iseq_parameters(iseq);
+}
+
 /*
  * call-seq:
@@ -1461,4 +1500,6 @@ get_method_iseq(VALUE method)
     body = data->body;
     switch (nd_type(body)) {
+      case NODE_BMETHOD:
+	return get_proc_iseq(body->nd_cval);
       case RUBY_VM_METHOD_NODE:
 	GetISeqPtr((VALUE)body->nd_body, iseq);
@@ -1485,4 +1526,22 @@ rb_method_location(VALUE method)
 
 /*
+ * call-seq:
+ *    meth.parameters  => array
+ *
+ * returns the parameter information of this method
+ * or nil if this method was not defined in ruby (i.e. native)
+ */
+
+static VALUE
+rb_method_parameters(VALUE method)
+{
+    rb_iseq_t *iseq = get_method_iseq(method);
+    if (!iseq) {
+	return unnamed_parameters(method_arity(method));
+    }
+    return rb_iseq_parameters(iseq);
+}
+
+/*
  *  call-seq:
  *   meth.to_s      =>  string
@@ -1812,4 +1871,5 @@ Init_Proc(void)
     rb_define_method(rb_cProc, "curry", proc_curry, -1);
     rb_define_method(rb_cProc, "source_location", rb_proc_location, 0);
+    rb_define_method(rb_cProc, "parameters", rb_proc_parameters, 0);
 
     /* Exceptions */
@@ -1847,4 +1907,5 @@ Init_Proc(void)
     rb_define_method(rb_cMethod, "unbind", method_unbind, 0);
     rb_define_method(rb_cMethod, "source_location", rb_method_location, 0);
+    rb_define_method(rb_cMethod, "parameters", rb_method_parameters, 0);
     rb_define_method(rb_mKernel, "method", rb_obj_method, 1);
     rb_define_method(rb_mKernel, "public_method", rb_obj_public_method, 1);
@@ -1865,4 +1926,5 @@ Init_Proc(void)
     rb_define_method(rb_cUnboundMethod, "bind", umethod_bind, 1);
     rb_define_method(rb_cUnboundMethod, "source_location", rb_method_location, 0);
+    rb_define_method(rb_cUnboundMethod, "parameters", rb_method_parameters, 0);
 
     /* Module#*_method */
Index: test/ruby/test_method.rb
===================================================================
--- test/ruby/test_method.rb	(revision 20232)
+++ test/ruby/test_method.rb	(working copy)
@@ -21,4 +21,6 @@ class TestMethod < Test::Unit::TestCase
   def mo5(a, *b, c) end
   def mo6(a, *b, c, &d) end
+  def mo7(a, b = nil, *c, d, &e) end
+  def ma1((a), &b) end
 
   class Base
@@ -222,3 +224,71 @@ class TestMethod < Test::Unit::TestCase
     assert_raise(ArgumentError) { o.method(:foo).call(1) }
   end
+
+  define_method(:pm0) {||}
+  define_method(:pm1) {|a|}
+  define_method(:pm2) {|a, b|}
+  define_method(:pmo1) {|a = nil, &b|}
+  define_method(:pmo2) {|a, b = nil|}
+  define_method(:pmo3) {|*a|}
+  define_method(:pmo4) {|a, *b, &c|}
+  define_method(:pmo5) {|a, *b, c|}
+  define_method(:pmo6) {|a, *b, c, &d|}
+  define_method(:pmo7) {|a, b = nil, *c, d, &e|}
+  define_method(:pma1) {|(a), &b|}
+
+  def test_bound_parameters
+    assert_equal(%w(), method(:m0).parameters)
+    assert_equal(%w(a), method(:m1).parameters)
+    assert_equal(%w(a b), method(:m2).parameters)
+    assert_equal(%w(?a &b), method(:mo1).parameters)
+    assert_equal(%w(a ?b), method(:mo2).parameters)
+    assert_equal(%w(*a), method(:mo3).parameters)
+    assert_equal(%w(a *b &c), method(:mo4).parameters)
+    assert_equal(%w(a *b c), method(:mo5).parameters)
+    assert_equal(%w(a *b c &d), method(:mo6).parameters)
+    assert_equal(%w(a ?b *c d &e), method(:mo7).parameters)
+    assert_equal([nil, "&b"], method(:ma1).parameters)
+  end
+
+  def test_unbound_parameters
+    assert_equal(%w(), self.class.instance_method(:m0).parameters)
+    assert_equal(%w(a), self.class.instance_method(:m1).parameters)
+    assert_equal(%w(a b), self.class.instance_method(:m2).parameters)
+    assert_equal(%w(?a &b), self.class.instance_method(:mo1).parameters)
+    assert_equal(%w(a ?b), self.class.instance_method(:mo2).parameters)
+    assert_equal(%w(*a), self.class.instance_method(:mo3).parameters)
+    assert_equal(%w(a *b &c), self.class.instance_method(:mo4).parameters)
+    assert_equal(%w(a *b c), self.class.instance_method(:mo5).parameters)
+    assert_equal(%w(a *b c &d), self.class.instance_method(:mo6).parameters)
+    assert_equal(%w(a ?b *c d &e), self.class.instance_method(:mo7).parameters)
+    assert_equal([nil, "&b"], self.class.instance_method(:ma1).parameters)
+  end
+
+  def test_bmethod_bound_parameters
+    assert_equal(%w(), method(:pm0).parameters)
+    assert_equal(%w(a), method(:pm1).parameters)
+    assert_equal(%w(a b), method(:pm2).parameters)
+    assert_equal(%w(?a &b), method(:pmo1).parameters)
+    assert_equal(%w(a ?b), method(:pmo2).parameters)
+    assert_equal(%w(*a), method(:pmo3).parameters)
+    assert_equal(%w(a *b &c), method(:pmo4).parameters)
+    assert_equal(%w(a *b c), method(:pmo5).parameters)
+    assert_equal(%w(a *b c &d), method(:pmo6).parameters)
+    assert_equal(%w(a ?b *c d &e), method(:pmo7).parameters)
+    assert_equal([nil, "&b"], method(:pma1).parameters)
+  end
+
+  def test_bmethod_unbound_parameters
+    assert_equal(%w(), self.class.instance_method(:pm0).parameters)
+    assert_equal(%w(a), self.class.instance_method(:pm1).parameters)
+    assert_equal(%w(a b), self.class.instance_method(:pm2).parameters)
+    assert_equal(%w(?a &b), self.class.instance_method(:pmo1).parameters)
+    assert_equal(%w(a ?b), self.class.instance_method(:pmo2).parameters)
+    assert_equal(%w(*a), self.class.instance_method(:pmo3).parameters)
+    assert_equal(%w(a *b &c), self.class.instance_method(:pmo4).parameters)
+    assert_equal(%w(a *b c), self.class.instance_method(:pmo5).parameters)
+    assert_equal(%w(a *b c &d), self.class.instance_method(:pmo6).parameters)
+    assert_equal(%w(a ?b *c d &e), self.class.instance_method(:pmo7).parameters)
+    assert_equal([nil, "&b"], self.class.instance_method(:pma1).parameters)
+  end
 end
Index: test/ruby/test_proc.rb
===================================================================
--- test/ruby/test_proc.rb	(revision 20232)
+++ test/ruby/test_proc.rb	(working copy)
@@ -674,3 +674,46 @@ class TestProc < Test::Unit::TestCase
     assert_equal([1,2,[3],4,5], r, "[ruby-core:19485]")
   end
+
+  def test_parameters
+    assert_equal(%w(), proc {}.parameters)
+    assert_equal(%w(), proc {||}.parameters)
+    assert_equal(%w(a), proc {|a|}.parameters)
+    assert_equal(%w(a b), proc {|a, b|}.parameters)
+    assert_equal(%w(?a &b), proc {|a=:a, &b|}.parameters)
+    assert_equal(%w(a ?b), proc {|a, b=:b|}.parameters)
+    assert_equal(%w(*a), proc {|*a|}.parameters)
+    assert_equal(%w(a *b &c), proc {|a, *b, &c|}.parameters)
+    assert_equal(%w(a *b c), proc {|a, *b, c|}.parameters)
+    assert_equal(%w(a *b c &d), proc {|a, *b, c, &d|}.parameters)
+    assert_equal(%w(a ?b *c d &e), proc {|a, b=:b, *c, d, &e|}.parameters)
+    assert_equal([nil, "&b"], proc {|(a), &b|}.parameters)
+    assert_equal(%w[a b ?c ?d *e f g &h], proc {|a,b,c=:c,d=:d,*e,f,g,&h|}.parameters) 
+  end
+
+  def pm0() end
+  def pm1(a) end
+  def pm2(a, b) end
+  def pmo1(a = nil, &b) end
+  def pmo2(a, b = nil) end
+  def pmo3(*a) end
+  def pmo4(a, *b, &c) end
+  def pmo5(a, *b, c) end
+  def pmo6(a, *b, c, &d) end
+  def pmo7(a, b = nil, *c, d, &e) end
+  def pma1((a), &b) end
+
+
+  def test_bound_parameters
+    assert_equal(%w(), method(:pm0).to_proc.parameters)
+    assert_equal(%w(a), method(:pm1).to_proc.parameters)
+    assert_equal(%w(a b), method(:pm2).to_proc.parameters)
+    assert_equal(%w(?a &b), method(:pmo1).to_proc.parameters)
+    assert_equal(%w(a ?b), method(:pmo2).to_proc.parameters)
+    assert_equal(%w(*a), method(:pmo3).to_proc.parameters)
+    assert_equal(%w(a *b &c), method(:pmo4).to_proc.parameters)
+    assert_equal(%w(a *b c), method(:pmo5).to_proc.parameters)
+    assert_equal(%w(a *b c &d), method(:pmo6).to_proc.parameters)
+    assert_equal(%w(a ?b *c d &e), method(:pmo7).to_proc.parameters)
+    assert_equal([nil, "&b"], method(:pma1).to_proc.parameters)
+  end
 end


-- 
Nobu Nakada