Merge branch 'DragonRuby:master' into masterHEADmaster

5 files changed, 132 insertions, 39 deletions

diff --git a/samples/12_c_extensions/.gitignore b/samples/12_c_extensions/.gitignore
new file mode 100644
index 0000000..a90a836
--- /dev/null
+++ b/samples/12_c_extensions/.gitignore
@@ -0,0 +1,2 @@
+ext.dylib
+
diff --git a/samples/12_c_extensions/01_basics/native/ext-bindings.c b/samples/12_c_extensions/01_basics/native/ext-bindings.c
index c805961..86b7090 100644
--- a/samples/12_c_extensions/01_basics/native/ext-bindings.c
+++ b/samples/12_c_extensions/01_basics/native/ext-bindings.c
@@ -14,7 +14,13 @@
 #undef mrb_int
 #endif
 
+void *(*drb_symbol_lookup)(const char *sym) = NULL;
+
 static void (*drb_free_foreign_object_f)(mrb_state *, void *);
+static void (*drb_typecheck_float_f)(mrb_state *, mrb_value);
+static void (*drb_typecheck_int_f)(mrb_state *, mrb_value);
+static void (*drb_typecheck_bool_f)(mrb_state *, mrb_value);
+static void (*drb_typecheck_aggregate_f)(mrb_state *, mrb_value, struct RClass *, mrb_data_type *);
 static struct RClass *(*mrb_module_get_f)(mrb_state *, const char *);
 static mrb_int (*mrb_get_args_f)(mrb_state *, mrb_args_format, ...);
 static struct RClass *(*mrb_module_get_under_f)(mrb_state *, struct RClass *, const char *);
@@ -27,7 +33,13 @@ static void (*mrb_define_class_method_f)(mrb_state *, struct RClass *, const cha
 static struct RData *(*mrb_data_object_alloc_f)(mrb_state *, struct RClass *, void *, const mrb_data_type *);
 static mrb_value (*mrb_str_new_cstr_f)(mrb_state *, const char *);
 static void (*mrb_raise_f)(mrb_state *, struct RClass *, const char *);
+static mrb_value (*drb_float_value_f)(mrb_state *, mrb_float);
+static struct RClass *(*drb_getruntime_error_f)(mrb_state *);
+static void drb_free_foreign_object_indirect(mrb_state *state, void *pointer) {
+    drb_free_foreign_object_f(state, pointer);
+}
 static int drb_ffi__ZTSi_FromRuby(mrb_state *state, mrb_value self) {
+    drb_typecheck_int_f(state, self);
     return mrb_fixnum(self);
 }
 static mrb_value drb_ffi__ZTSi_ToRuby(mrb_state *state, int value) {
@@ -51,18 +63,25 @@ void drb_register_c_extensions(void *(*lookup)(const char *), mrb_state *state,
     mrb_define_module_function_f(state, module, "square", drb_ffi_square_Binding, MRB_ARGS_REQ(1));
 }
 static int drb_ffi_init_indirect_functions(void *(*lookup)(const char *fnname)) {
-  if (!(mrb_raise_f = (void (*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_raise"))) return -1;
-  if (!(mrb_module_get_f = (struct RClass *(*)(mrb_state *, const char *)) lookup("mrb_module_get"))) return -1;
-  if (!(mrb_class_get_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_class_get_under"))) return -1;
-  if (!(mrb_get_args_f = (mrb_int (*)(mrb_state *, mrb_args_format, ...)) lookup("mrb_get_args"))) return -1;
+  drb_symbol_lookup = lookup;
+  if (!(drb_float_value_f = (mrb_value (*)(mrb_state *, mrb_float)) lookup("drb_float_value"))) return -1;
   if (!(drb_free_foreign_object_f = (void (*)(mrb_state *, void *)) lookup("drb_free_foreign_object"))) return -1;
-  if (!(mrb_define_module_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_define_module_under"))) return -1;
-  if (!(mrb_str_new_cstr_f = (mrb_value (*)(mrb_state *, const char *)) lookup("mrb_str_new_cstr"))) return -1;
+  if (!(drb_getruntime_error_f = (struct RClass *(*)(mrb_state *)) lookup("drb_getruntime_error"))) return -1;
+  if (!(drb_typecheck_aggregate_f = (void (*)(mrb_state *, mrb_value, struct RClass *, mrb_data_type *)) lookup("drb_typecheck_aggregate"))) return -1;
+  if (!(drb_typecheck_bool_f = (void (*)(mrb_state *, mrb_value)) lookup("drb_typecheck_bool"))) return -1;
+  if (!(drb_typecheck_float_f = (void (*)(mrb_state *, mrb_value)) lookup("drb_typecheck_float"))) return -1;
+  if (!(drb_typecheck_int_f = (void (*)(mrb_state *, mrb_value)) lookup("drb_typecheck_int"))) return -1;
+  if (!(mrb_class_get_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_class_get_under"))) return -1;
+  if (!(mrb_data_object_alloc_f = (struct RData *(*)(mrb_state *, struct RClass *, void *, const mrb_data_type *)) lookup("mrb_data_object_alloc"))) return -1;
+  if (!(mrb_define_class_method_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_class_method"))) return -1;
   if (!(mrb_define_class_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *, struct RClass *)) lookup("mrb_define_class_under"))) return -1;
+  if (!(mrb_define_method_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_method"))) return -1;
   if (!(mrb_define_module_function_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_module_function"))) return -1;
-  if (!(mrb_data_object_alloc_f = (struct RData *(*)(mrb_state *, struct RClass *, void *, const mrb_data_type *)) lookup("mrb_data_object_alloc"))) return -1;
+  if (!(mrb_define_module_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_define_module_under"))) return -1;
+  if (!(mrb_get_args_f = (mrb_int (*)(mrb_state *, mrb_args_format, ...)) lookup("mrb_get_args"))) return -1;
+  if (!(mrb_module_get_f = (struct RClass *(*)(mrb_state *, const char *)) lookup("mrb_module_get"))) return -1;
   if (!(mrb_module_get_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_module_get_under"))) return -1;
-  if (!(mrb_define_method_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_method"))) return -1;
-  if (!(mrb_define_class_method_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_class_method"))) return -1;
+  if (!(mrb_raise_f = (void (*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_raise"))) return -1;
+  if (!(mrb_str_new_cstr_f = (mrb_value (*)(mrb_state *, const char *)) lookup("mrb_str_new_cstr"))) return -1;
   return 0;
 }
diff --git a/samples/12_c_extensions/02_intermediate/native/re-bindings.c b/samples/12_c_extensions/02_intermediate/native/re-bindings.c
index 6aa5630..6bd9869 100644
--- a/samples/12_c_extensions/02_intermediate/native/re-bindings.c
+++ b/samples/12_c_extensions/02_intermediate/native/re-bindings.c
@@ -14,7 +14,13 @@
 #undef mrb_int
 #endif
 
+void *(*drb_symbol_lookup)(const char *sym) = NULL;
+
 static void (*drb_free_foreign_object_f)(mrb_state *, void *);
+static void (*drb_typecheck_float_f)(mrb_state *, mrb_value);
+static void (*drb_typecheck_int_f)(mrb_state *, mrb_value);
+static void (*drb_typecheck_bool_f)(mrb_state *, mrb_value);
+static void (*drb_typecheck_aggregate_f)(mrb_state *, mrb_value, struct RClass *, mrb_data_type *);
 static struct RClass *(*mrb_module_get_f)(mrb_state *, const char *);
 static mrb_int (*mrb_get_args_f)(mrb_state *, mrb_args_format, ...);
 static struct RClass *(*mrb_module_get_under_f)(mrb_state *, struct RClass *, const char *);
@@ -27,10 +33,18 @@ static void (*mrb_define_class_method_f)(mrb_state *, struct RClass *, const cha
 static struct RData *(*mrb_data_object_alloc_f)(mrb_state *, struct RClass *, void *, const mrb_data_type *);
 static mrb_value (*mrb_str_new_cstr_f)(mrb_state *, const char *);
 static void (*mrb_raise_f)(mrb_state *, struct RClass *, const char *);
-static struct RClass *(*mrb_exc_get_f)(mrb_state *, const char *);
+static mrb_value (*drb_float_value_f)(mrb_state *, mrb_float);
+static struct RClass *(*drb_getruntime_error_f)(mrb_state *);
 static void drb_free_foreign_object_indirect(mrb_state *state, void *pointer) {
     drb_free_foreign_object_f(state, pointer);
 }
+static int drb_ffi__ZTSi_FromRuby(mrb_state *state, mrb_value self) {
+    drb_typecheck_int_f(state, self);
+    return mrb_fixnum(self);
+}
+static mrb_value drb_ffi__ZTSi_ToRuby(mrb_state *state, int value) {
+    return mrb_fixnum_value(value);
+}
 struct drb_foreign_object_ZTSP7regex_t {
     drb_foreign_object_kind kind;
     struct regex_t *value;
@@ -40,6 +54,10 @@ static mrb_data_type ForeignObjectType_ZTSP7regex_t = {"regex_t*", drb_free_fore
 static struct regex_t *drb_ffi__ZTSP7regex_t_FromRuby(mrb_state *state, mrb_value self) {
     if (mrb_nil_p(self))
         return 0;
+    struct RClass *FFI = mrb_module_get_f(state, "FFI");
+    struct RClass *module = mrb_module_get_under_f(state, FFI, "RE");
+    struct RClass *klass = mrb_class_get_under_f(state, module, "Regex_tPointer");
+    drb_typecheck_aggregate_f(state, self, klass, &ForeignObjectType_ZTSP7regex_t);
     return ((struct drb_foreign_object_ZTSP7regex_t *)DATA_PTR(self))->value;
 }
 static mrb_value drb_ffi__ZTSP7regex_t_ToRuby(mrb_state *state, struct regex_t *value) {
@@ -63,6 +81,10 @@ static char *drb_ffi__ZTSPc_FromRuby(mrb_state *state, mrb_value self) {
         return 0;
     if (mrb_type(self) == MRB_TT_STRING)
         return RSTRING_PTR(self);
+    struct RClass *FFI = mrb_module_get_f(state, "FFI");
+    struct RClass *module = mrb_module_get_under_f(state, FFI, "RE");
+    struct RClass *klass = mrb_class_get_under_f(state, module, "CharPointer");
+    drb_typecheck_aggregate_f(state, self, klass, &ForeignObjectType_ZTSPc);
     return ((struct drb_foreign_object_ZTSPc *)DATA_PTR(self))->value;
 }
 static mrb_value drb_ffi__ZTSPc_ToRuby(mrb_state *state, char *value) {
@@ -75,12 +97,6 @@ static mrb_value drb_ffi__ZTSPc_ToRuby(mrb_state *state, char *value) {
     struct RData *rdata = mrb_data_object_alloc_f(state, klass, ptr, &ForeignObjectType_ZTSPc);
     return mrb_obj_value(rdata);
 }
-static int drb_ffi__ZTSi_FromRuby(mrb_state *state, mrb_value self) {
-    return mrb_fixnum(self);
-}
-static mrb_value drb_ffi__ZTSi_ToRuby(mrb_state *state, int value) {
-    return mrb_fixnum_value(value);
-}
 struct drb_foreign_object_ZTSPi {
     drb_foreign_object_kind kind;
     int *value;
@@ -90,6 +106,10 @@ static mrb_data_type ForeignObjectType_ZTSPi = {"int*", drb_free_foreign_object_
 static int *drb_ffi__ZTSPi_FromRuby(mrb_state *state, mrb_value self) {
     if (mrb_nil_p(self))
         return 0;
+    struct RClass *FFI = mrb_module_get_f(state, "FFI");
+    struct RClass *module = mrb_module_get_under_f(state, FFI, "RE");
+    struct RClass *klass = mrb_class_get_under_f(state, module, "IntPointer");
+    drb_typecheck_aggregate_f(state, self, klass, &ForeignObjectType_ZTSPi);
     return ((struct drb_foreign_object_ZTSPi *)DATA_PTR(self))->value;
 }
 static mrb_value drb_ffi__ZTSPi_ToRuby(mrb_state *state, int *value) {
@@ -103,17 +123,18 @@ static mrb_value drb_ffi__ZTSPi_ToRuby(mrb_state *state, int *value) {
     return mrb_obj_value(rdata);
 }
 static char drb_ffi__ZTSc_FromRuby(mrb_state *state, mrb_value self) {
+    drb_typecheck_int_f(state, self);
     return mrb_fixnum(self);
 }
 static mrb_value drb_ffi__ZTSc_ToRuby(mrb_state *state, char value) {
     return mrb_fixnum_value(value);
 }
 static mrb_value drb_ffi__ZTSP7regex_t_New(mrb_state *mrb, mrb_value self) {
-    mrb_raise_f(mrb, mrb_exc_get_f(mrb, "RuntimeError"), "Cannot allocate pointer of incomplete type");
+    mrb_raise_f(mrb, drb_getruntime_error_f(mrb), "Cannot allocate pointer of incomplete type");
     return mrb_nil_value();
 }
 static mrb_value drb_ffi__ZTSP7regex_t_GetValue(mrb_state *mrb, mrb_value value) {
-    mrb_raise_f(mrb, mrb_exc_get_f(mrb, "RuntimeError"), "Cannot access value of incomplete type");
+    mrb_raise_f(mrb, drb_getruntime_error_f(mrb), "Cannot access value of incomplete type");
     return mrb_nil_value();
 }
 static mrb_value drb_ffi__ZTSP7regex_t_IsNil(mrb_state *state, mrb_value self) {
@@ -123,11 +144,11 @@ static mrb_value drb_ffi__ZTSP7regex_t_IsNil(mrb_state *state, mrb_value self) {
         return mrb_false_value();
 }
 static mrb_value drb_ffi__ZTSP7regex_t_GetAt(mrb_state *mrb, mrb_value self) {
-    mrb_raise_f(mrb, mrb_exc_get_f(mrb, "RuntimeError"), "Cannot access value of incomplete type");
+    mrb_raise_f(mrb, drb_getruntime_error_f(mrb), "Cannot access value of incomplete type");
     return mrb_nil_value();
 }
 static mrb_value drb_ffi__ZTSP7regex_t_SetAt(mrb_state *mrb, mrb_value self) {
-    mrb_raise_f(mrb, mrb_exc_get_f(mrb, "RuntimeError"), "Cannot change value of incomplete type");
+    mrb_raise_f(mrb, drb_getruntime_error_f(mrb), "Cannot change value of incomplete type");
     return mrb_nil_value();
 }
 static mrb_value drb_ffi__ZTSPc_New(mrb_state *mrb, mrb_value self) {
@@ -264,19 +285,25 @@ void drb_register_c_extensions(void *(*lookup)(const char *), mrb_state *state,
     mrb_define_method_f(state, IntPointerClass, "nil?", drb_ffi__ZTSPi_IsNil, MRB_ARGS_REQ(0));
 }
 static int drb_ffi_init_indirect_functions(void *(*lookup)(const char *fnname)) {
-  if (!(mrb_raise_f = (void (*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_raise"))) return -1;
-  if (!(mrb_str_new_cstr_f = (mrb_value (*)(mrb_state *, const char *)) lookup("mrb_str_new_cstr"))) return -1;
-  if (!(mrb_define_class_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *, struct RClass *)) lookup("mrb_define_class_under"))) return -1;
-  if (!(mrb_define_class_method_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_class_method"))) return -1;
-  if (!(mrb_class_get_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_class_get_under"))) return -1;
-  if (!(mrb_module_get_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_module_get_under"))) return -1;
+  drb_symbol_lookup = lookup;
+  if (!(drb_float_value_f = (mrb_value (*)(mrb_state *, mrb_float)) lookup("drb_float_value"))) return -1;
   if (!(drb_free_foreign_object_f = (void (*)(mrb_state *, void *)) lookup("drb_free_foreign_object"))) return -1;
+  if (!(drb_getruntime_error_f = (struct RClass *(*)(mrb_state *)) lookup("drb_getruntime_error"))) return -1;
+  if (!(drb_typecheck_aggregate_f = (void (*)(mrb_state *, mrb_value, struct RClass *, mrb_data_type *)) lookup("drb_typecheck_aggregate"))) return -1;
+  if (!(drb_typecheck_bool_f = (void (*)(mrb_state *, mrb_value)) lookup("drb_typecheck_bool"))) return -1;
+  if (!(drb_typecheck_float_f = (void (*)(mrb_state *, mrb_value)) lookup("drb_typecheck_float"))) return -1;
+  if (!(drb_typecheck_int_f = (void (*)(mrb_state *, mrb_value)) lookup("drb_typecheck_int"))) return -1;
+  if (!(mrb_class_get_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_class_get_under"))) return -1;
   if (!(mrb_data_object_alloc_f = (struct RData *(*)(mrb_state *, struct RClass *, void *, const mrb_data_type *)) lookup("mrb_data_object_alloc"))) return -1;
-  if (!(mrb_get_args_f = (mrb_int (*)(mrb_state *, mrb_args_format, ...)) lookup("mrb_get_args"))) return -1;
-  if (!(mrb_module_get_f = (struct RClass *(*)(mrb_state *, const char *)) lookup("mrb_module_get"))) return -1;
+  if (!(mrb_define_class_method_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_class_method"))) return -1;
+  if (!(mrb_define_class_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *, struct RClass *)) lookup("mrb_define_class_under"))) return -1;
   if (!(mrb_define_method_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_method"))) return -1;
-  if (!(mrb_exc_get_f = (struct RClass *(*)(mrb_state *, const char *)) lookup("mrb_exc_get"))) return -1;
   if (!(mrb_define_module_function_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_module_function"))) return -1;
   if (!(mrb_define_module_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_define_module_under"))) return -1;
+  if (!(mrb_get_args_f = (mrb_int (*)(mrb_state *, mrb_args_format, ...)) lookup("mrb_get_args"))) return -1;
+  if (!(mrb_module_get_f = (struct RClass *(*)(mrb_state *, const char *)) lookup("mrb_module_get"))) return -1;
+  if (!(mrb_module_get_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_module_get_under"))) return -1;
+  if (!(mrb_raise_f = (void (*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_raise"))) return -1;
+  if (!(mrb_str_new_cstr_f = (mrb_value (*)(mrb_state *, const char *)) lookup("mrb_str_new_cstr"))) return -1;
   return 0;
 }
diff --git a/samples/12_c_extensions/03_native_pixel_arrays/native/ext-bindings.c b/samples/12_c_extensions/03_native_pixel_arrays/native/ext-bindings.c
index c0a923c..bdba6e7 100644
--- a/samples/12_c_extensions/03_native_pixel_arrays/native/ext-bindings.c
+++ b/samples/12_c_extensions/03_native_pixel_arrays/native/ext-bindings.c
@@ -17,6 +17,10 @@
 void *(*drb_symbol_lookup)(const char *sym) = NULL;
 
 static void (*drb_free_foreign_object_f)(mrb_state *, void *);
+static void (*drb_typecheck_float_f)(mrb_state *, mrb_value);
+static void (*drb_typecheck_int_f)(mrb_state *, mrb_value);
+static void (*drb_typecheck_bool_f)(mrb_state *, mrb_value);
+static void (*drb_typecheck_aggregate_f)(mrb_state *, mrb_value, struct RClass *, mrb_data_type *);
 static struct RClass *(*mrb_module_get_f)(mrb_state *, const char *);
 static mrb_int (*mrb_get_args_f)(mrb_state *, mrb_args_format, ...);
 static struct RClass *(*mrb_module_get_under_f)(mrb_state *, struct RClass *, const char *);
@@ -29,10 +33,18 @@ static void (*mrb_define_class_method_f)(mrb_state *, struct RClass *, const cha
 static struct RData *(*mrb_data_object_alloc_f)(mrb_state *, struct RClass *, void *, const mrb_data_type *);
 static mrb_value (*mrb_str_new_cstr_f)(mrb_state *, const char *);
 static void (*mrb_raise_f)(mrb_state *, struct RClass *, const char *);
-static struct RClass *(*mrb_exc_get_f)(mrb_state *, const char *);
+static mrb_value (*drb_float_value_f)(mrb_state *, mrb_float);
+static struct RClass *(*drb_getruntime_error_f)(mrb_state *);
 static void drb_free_foreign_object_indirect(mrb_state *state, void *pointer) {
     drb_free_foreign_object_f(state, pointer);
 }
+static int drb_ffi__ZTSi_FromRuby(mrb_state *state, mrb_value self) {
+    drb_typecheck_int_f(state, self);
+    return mrb_fixnum(self);
+}
+static mrb_value drb_ffi__ZTSi_ToRuby(mrb_state *state, int value) {
+    return mrb_fixnum_value(value);
+}
 static mrb_value drb_ffi_update_scanner_texture_Binding(mrb_state *state, mrb_value value) {
     update_scanner_texture();
     return mrb_nil_value();
@@ -48,19 +60,24 @@ void drb_register_c_extensions(void *(*lookup)(const char *), mrb_state *state,
 }
 static int drb_ffi_init_indirect_functions(void *(*lookup)(const char *fnname)) {
   drb_symbol_lookup = lookup;
-  if (!(mrb_exc_get_f = (struct RClass *(*)(mrb_state *, const char *)) lookup("mrb_exc_get"))) return -1;
-  if (!(mrb_raise_f = (void (*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_raise"))) return -1;
-  if (!(mrb_class_get_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_class_get_under"))) return -1;
-  if (!(mrb_module_get_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_module_get_under"))) return -1;
+  if (!(drb_float_value_f = (mrb_value (*)(mrb_state *, mrb_float)) lookup("drb_float_value"))) return -1;
   if (!(drb_free_foreign_object_f = (void (*)(mrb_state *, void *)) lookup("drb_free_foreign_object"))) return -1;
-  if (!(mrb_module_get_f = (struct RClass *(*)(mrb_state *, const char *)) lookup("mrb_module_get"))) return -1;
-  if (!(mrb_define_module_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_define_module_under"))) return -1;
+  if (!(drb_getruntime_error_f = (struct RClass *(*)(mrb_state *)) lookup("drb_getruntime_error"))) return -1;
+  if (!(drb_typecheck_aggregate_f = (void (*)(mrb_state *, mrb_value, struct RClass *, mrb_data_type *)) lookup("drb_typecheck_aggregate"))) return -1;
+  if (!(drb_typecheck_bool_f = (void (*)(mrb_state *, mrb_value)) lookup("drb_typecheck_bool"))) return -1;
+  if (!(drb_typecheck_float_f = (void (*)(mrb_state *, mrb_value)) lookup("drb_typecheck_float"))) return -1;
+  if (!(drb_typecheck_int_f = (void (*)(mrb_state *, mrb_value)) lookup("drb_typecheck_int"))) return -1;
+  if (!(mrb_class_get_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_class_get_under"))) return -1;
   if (!(mrb_data_object_alloc_f = (struct RData *(*)(mrb_state *, struct RClass *, void *, const mrb_data_type *)) lookup("mrb_data_object_alloc"))) return -1;
+  if (!(mrb_define_class_method_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_class_method"))) return -1;
+  if (!(mrb_define_class_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *, struct RClass *)) lookup("mrb_define_class_under"))) return -1;
+  if (!(mrb_define_method_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_method"))) return -1;
   if (!(mrb_define_module_function_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_module_function"))) return -1;
+  if (!(mrb_define_module_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_define_module_under"))) return -1;
   if (!(mrb_get_args_f = (mrb_int (*)(mrb_state *, mrb_args_format, ...)) lookup("mrb_get_args"))) return -1;
-  if (!(mrb_define_method_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_method"))) return -1;
-  if (!(mrb_define_class_method_f = (void (*)(mrb_state *, struct RClass *, const char *, mrb_func_t, mrb_aspec)) lookup("mrb_define_class_method"))) return -1;
+  if (!(mrb_module_get_f = (struct RClass *(*)(mrb_state *, const char *)) lookup("mrb_module_get"))) return -1;
+  if (!(mrb_module_get_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_module_get_under"))) return -1;
+  if (!(mrb_raise_f = (void (*)(mrb_state *, struct RClass *, const char *)) lookup("mrb_raise"))) return -1;
   if (!(mrb_str_new_cstr_f = (mrb_value (*)(mrb_state *, const char *)) lookup("mrb_str_new_cstr"))) return -1;
-  if (!(mrb_define_class_under_f = (struct RClass *(*)(mrb_state *, struct RClass *, const char *, struct RClass *)) lookup("mrb_define_class_under"))) return -1;
   return 0;
 }
diff --git a/samples/12_c_extensions/README.md b/samples/12_c_extensions/README.md
index 8950e53..aef3864 100644
--- a/samples/12_c_extensions/README.md
+++ b/samples/12_c_extensions/README.md
@@ -350,6 +350,34 @@ dragonruby-bind --ffi-module=CoolStuff bridge.c
 
 Then one can use `include FFI::CoolStuff` instead.
 
+### Type checks
+
+C extensions expect the right types in the right place!
+
+Given the following C code:
+
+```c
+void take_int(int x) { ... }
+void take_struct(struct S) { ... }
+```
+
+the next calls from the Ruby side
+
+```ruby
+take_int(15.0)
+take_struct(42)
+```
+
+may not work as you would expect.
+In the case of `take_int`, you'll likely see some garbage instead of "expected" `15`.
+The call to `take_struct` will likely crash.
+
+To prevent this from happening, `dragonruby-bind` emits code that does type checking:
+if you use the wrong types DragonRuby will throw an exception.
+
+If the type checking takes CPU cycles out of your game (or if you feel brave) you can
+disable type checks via `--no-typecheck` CLI argument when emitting C bindings.
+
 ### Pitfalls
 
 There is no so-called marshalling when it comes to structs. When you read or