[ruby-core:91009] [Ruby trunk Feature#14145] Proposal: Better Method#inspect

Issue #14145 has been updated by ko1 (Koichi Sasada).


Eregon (Benoit Daloze) wrote:
> ko1 (Koichi Sasada) wrote:
> > I don't have strong opinions on your proposal, but source location information seems also helpful. Which is important or both?
> 
> I find source location (FILE:LINE) very valuable for debugging, e.g. to know if a method was overriden and to quickly check the source in my editor.

+1. I'm using `#source_location` like `p method(:foo).source_location` sometimes to know the definition. If "Method#inspect" shows this information, it will help *me*.

Also, `Proc#inspect` shows source location.  `p proc{} #=> #<Proc:[e-mail]:1>`

```
class C
  def m
  end
end

p C.new.method(:m) #=> #<Method: C#m@/home/ko1/src/ruby/trunk/test.rb:3 >
```

patch:

```
Index: proc.c
===================================================================
--- proc.c	(リビジョン 66764)
+++ proc.c	(作業コピー)
@@ -2681,6 +2681,16 @@
     if (data->me->def->type == VM_METHOD_TYPE_NOTIMPLEMENTED) {
         rb_str_buf_cat2(str, " (not-implemented)");
     }
+
+    {
+        VALUE loc = rb_method_location(method);
+        if (!NIL_P(loc)) {
+            VALUE loc_str = rb_sprintf("@%"PRIsVALUE":%"PRIsVALUE" ",
+                                       RARRAY_AREF(loc, 0), RARRAY_AREF(loc, 1));
+            rb_str_buf_append(str, loc_str);
+        }
+    }
+
     rb_str_buf_cat2(str, ">");
 
     return str;
```



----------------------------------------
Feature #14145: Proposal: Better Method#inspect
https://bugs.ruby-lang.org/issues/14145#change-76230

* Author: zverok (Victor Shepelev)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
The idea: When investigating (in example scripts, debugger or console) the library you are unfamiliar with, Ruby's reflection is very useful mechanism to understand "what it can": classes, modules, their constants, methods and so on.
I propose to expose a bit more information Ruby has internally in `Method#inspect`:


```ruby
# before:
some_interesting_object.method(:foo) # => #<Method Klass#foo>
# after:
some_interesting_object.method(:foo) # => #<Method Klass#foo(first_arg, *other_args, keyword_arg:)>
```

Dead-naive implementation:

```ruby
class Method
  def signature
    recv = case receiver
    when Module
      "#{receiver.name}."
    else
      "#{receiver.class}#"
    end
    parameters.map.with_index { |(type, name), i|
      case type
      when :req then "#{name || "param#{i+1}"}"
      when :opt then "#{name || "param#{i+1}"} = <default>"
      when :keyreq then "#{name || "kw#{i+1}"}:"
      when :key then "#{name || "kwparam#{i+1}"}: <default>"
      when :rest then "*#{name || "rest"}"
      when :keyrest then "**#{name || "kwrest"}"
      end
    }.join(', ').prepend("#{recv}#{name}(") << ")"
  end

  def inspect
    "#<#{self.class.name} #{signature}>"
  end
end

```

This works "sub-optimal" for methods implemented in C, yet pretty decently for Ruby-implemented methods:

```ruby
# C method, default param names
[1,2,3].method(:at)
# => #<Method Array#at(param1)>

# Ruby method, proper param names
CGI.method(:escape)
# => #<Method CGI.escape(string)>
Addressable::URI.method(:parse)
# => #<Method Addressable::URI.parse(uri)>
Addressable::URI.method(:join)
 => #<Method Addressable::URI.join(*uris)>

# We can't extract default values, but at least we can say they are there
Addressable::URI.method(:heuristic_parse)
# => #<Method Addressable::URI.heuristic_parse(uri, hints = <default>)>
```

If the proposal is accepted, I am ready to implement it properly in C (for all callable objects: `Method`, `UnboundMethod`, `Proc`)



-- 
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