[ruby-core:84007] [Ruby trunk Feature#14145] Proposal: Better Method#inspect

Issue #14145 has been updated by Hanmac (Hans Mackowiak).




@zverok some changes for your code: 
use Method#owner to get the class/module where the method is defined
that can make a difference for Singleton methods on a non-module object


Thema:

i think this change would be okay, but i am indifferent about the C-level funtions

for my bindings i do overload the methods depending on the type and amount of parameters
no need to show more of the code but this is the documenation block

~~~ cpp
/*
 * call-seq:
 *   contains?(x, y) -> bool
 *   contains?(point) -> bool
 *   contains?(rect) -> bool
 *
 * return true if the point or the rect is (not strictly) inside this rect
 * ===Arguments
 * * x and y are Integer
 * * pos is a WX::Point
 * * rect is a WX::Rect
 * ===Return value
 * bool
 *
 */
~~~

as you guys can see there are different cases,
because how ruby defines methods and use rb_scan_args,

my function returns parameters also just [:rest]


for most Ruby C-Api functions, there might be a way to make parameters return something useful,
but that's probably not the case for all functions

----------------------------------------
Feature #14145: Proposal: Better Method#inspect
https://bugs.ruby-lang.org/issues/14145#change-68089

* 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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