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instance method
Method#inspect
meth.inspect → string
proc.c
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static VALUE
method_inspect(VALUE method)
{
struct METHOD *data;
VALUE str;
const char *sharp = "#";
VALUE mklass;
VALUE defined_class;
TypedData_Get_Struct(method, struct METHOD, &method_data_type, data);
str = rb_sprintf("#<% "PRIsVALUE": ", rb_obj_class(method));
mklass = data->iclass;
if (!mklass) mklass = data->klass;
if (RB_TYPE_P(mklass, T_ICLASS)) {
/* TODO: I'm not sure why mklass is T_ICLASS.
* UnboundMethod#bind() can set it as T_ICLASS at convert_umethod_to_method_components()
* but not sure it is needed.
*/
mklass = RBASIC_CLASS(mklass);
}
if (data->me->def->type == VM_METHOD_TYPE_ALIAS) {
defined_class = data->me->def->body.alias.original_me->owner;
}
else {
defined_class = method_entry_defined_class(data->me);
}
if (RB_TYPE_P(defined_class, T_ICLASS)) {
defined_class = RBASIC_CLASS(defined_class);
}
if (FL_TEST(mklass, FL_SINGLETON)) {
VALUE v = rb_ivar_get(mklass, attached);
if (data->recv == Qundef) {
rb_str_buf_append(str, rb_inspect(mklass));
}
else if (data->recv == v) {
rb_str_buf_append(str, rb_inspect(v));
sharp = ".";
}
else {
rb_str_buf_append(str, rb_inspect(data->recv));
rb_str_buf_cat2(str, "(");
rb_str_buf_append(str, rb_inspect(v));
rb_str_buf_cat2(str, ")");
sharp = ".";
}
}
else {
mklass = data->klass;
if (FL_TEST(mklass, FL_SINGLETON)) {
VALUE v = rb_ivar_get(mklass, attached);
if (!(RB_TYPE_P(v, T_CLASS) || RB_TYPE_P(v, T_MODULE))) {
do {
mklass = RCLASS_SUPER(mklass);
} while (RB_TYPE_P(mklass, T_ICLASS));
}
}
rb_str_buf_append(str, rb_inspect(mklass));
if (defined_class != mklass) {
rb_str_catf(str, "(% "PRIsVALUE")", defined_class);
}
}
rb_str_buf_cat2(str, sharp);
rb_str_append(str, rb_id2str(data->me->called_id));
if (data->me->called_id != data->me->def->original_id) {
rb_str_catf(str, "(%"PRIsVALUE")",
rb_id2str(data->me->def->original_id));
}
if (data->me->def->type == VM_METHOD_TYPE_NOTIMPLEMENTED) {
rb_str_buf_cat2(str, " (not-implemented)");
}
// parameter information
{
VALUE params = rb_method_parameters(method);
VALUE pair, name, kind;
const VALUE req = ID2SYM(rb_intern("req"));
const VALUE opt = ID2SYM(rb_intern("opt"));
const VALUE keyreq = ID2SYM(rb_intern("keyreq"));
const VALUE key = ID2SYM(rb_intern("key"));
const VALUE rest = ID2SYM(rb_intern("rest"));
const VALUE keyrest = ID2SYM(rb_intern("keyrest"));
const VALUE block = ID2SYM(rb_intern("block"));
const VALUE nokey = ID2SYM(rb_intern("nokey"));
int forwarding = 0;
rb_str_buf_cat2(str, "(");
for (int i = 0; i < RARRAY_LEN(params); i++) {
pair = RARRAY_AREF(params, i);
kind = RARRAY_AREF(pair, 0);
name = RARRAY_AREF(pair, 1);
// FIXME: in tests it turns out that kind, name = [:req] produces name to be false. Why?..
if (NIL_P(name) || name == Qfalse) {
// FIXME: can it be reduced to switch/case?
if (kind == req || kind == opt) {
name = rb_str_new2("_");
}
else if (kind == rest || kind == keyrest) {
name = rb_str_new2("");
}
else if (kind == block) {
name = rb_str_new2("block");
}
else if (kind == nokey) {
name = rb_str_new2("nil");
}
}
if (kind == req) {
rb_str_catf(str, "%"PRIsVALUE, name);
}
else if (kind == opt) {
rb_str_catf(str, "%"PRIsVALUE"=...", name);
}
else if (kind == keyreq) {
rb_str_catf(str, "%"PRIsVALUE":", name);
}
else if (kind == key) {
rb_str_catf(str, "%"PRIsVALUE": ...", name);
}
else if (kind == rest) {
if (name == ID2SYM('*')) {
forwarding = 1;
rb_str_cat_cstr(str, "...");
}
else {
rb_str_catf(str, "*%"PRIsVALUE, name);
}
}
else if (kind == keyrest) {
rb_str_catf(str, "**%"PRIsVALUE, name);
}
else if (kind == block) {
if (name == ID2SYM('&')) {
if (forwarding) {
rb_str_set_len(str, RSTRING_LEN(str) - 2);
}
else {
rb_str_cat_cstr(str, "...");
}
}
else {
rb_str_catf(str, "&%"PRIsVALUE, name);
}
}
else if (kind == nokey) {
rb_str_buf_cat2(str, "**nil");
}
if (i < RARRAY_LEN(params) - 1) {
rb_str_buf_cat2(str, ", ");
}
}
rb_str_buf_cat2(str, ")");
}
{ // source location
VALUE loc = rb_method_location(method);
if (!NIL_P(loc)) {
rb_str_catf(str, " %"PRIsVALUE":%"PRIsVALUE,
RARRAY_AREF(loc, 0), RARRAY_AREF(loc, 1));
}
}
rb_str_buf_cat2(str, ">");
return str;
}
Returns a human-readable description of the underlying method.
Example
"cat".method(:count).inspect #=> "#<Method: String#count(*)>" (1..3).method(:map).inspect #=> "#<Method: Range(Enumerable)#map()>"
In the latter case, the method description includes the “owner” of the original method (Enumerable module, which is included into Range).
inspect also provides, when possible, method argument names (call sequence) and source location.
Example
require 'net/http' Net::HTTP.method(:get).inspect #=> "#<Method: Net::HTTP.get(uri_or_host, path=..., port=...) <skip>/lib/ruby/2.7.0/net/http.rb:457>"
... in argument definition means argument is optional (has some default value).
For methods defined in C (language core and extensions), location and argument names can’t be extracted, and only generic information is provided in form of * (any number of arguments) or _ (some positional argument).
Example
"cat".method(:count).inspect #=> "#<Method: String#count(*)>" "cat".method(:+).inspect #=> "#<Method: String#+(_)>""