Feature #18913
closedAdd object name to the NoMethodError error message: undefined method `_method_' for `_class_' in `_object_name_'
Description
Hi
I think the NoMethodError
error message is missing the object name. The object name is already present in NameError
. Currently one needs to dig into the source code and debug it in order to find which variable or method is actually affected.
The current error message looks like this:
bar = nil
bar.i_wish_i_saw_the_name_bar
# (irb):00:in `<main>': undefined method `i_wish_i_saw_the_name_bar' for nil:NilClass (NoMethodError)
I wish that it was more like this
bar = nil
bar.i_wish_i_saw_the_name_bar
#(irb):00:in `<main>': undefined method `i_wish_i_saw_the_name_bar' for nil:NilClass in `bar' (NoMethodError)
# ^^^ It should mention the object name
The NameError error message supports this already, and I think it avoids a whole lot of issue tickets, stackoverflow searches and more. See NoMethodError vs NameError https://trends.google.ch/trends/explore?date=today%205-y&q=ruby%20%20NoMethodError,ruby%20NameError
foo
# (irb):00:in `<main>': undefined local variable or method `foo' for main:Object (NameError)
# ^^^ the object name is mentioned
One can always use the backtrace to find the affected line, but even that won't help in the following situation:
a = OpenStruct.new
b = nil
c = nil
who_failed = a.foo & b.foo & c.foo
# (irb):00:in `<main>': undefined method `foo' for nil:NilClass (NoMethodError)
I would add the object name at the end of the exception message not to break compatibility. I hope most users use regex to match the exception message.
I don't know how to program c but I think the source is located here
https://github.com/ruby/ruby/blob/554befb/proc.c#L1959
I assume there will be some edge cases around meta programming and procs. Anyway, I think we should show them if available. I think we all spent many hours tracking down when we have a type/method mismatch, and this would have helped greatly.
Updated by stillhart (Fabian Stillhart) about 2 years ago
- Tracker changed from Bug to Feature
- ruby -v deleted (
ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x86_64-linux]) - Backport deleted (
2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN)
Updated by mame (Yusuke Endoh) about 2 years ago
I don't understand what you mean by "object name", but did you try Ruby 3.1? It shows a code snippet that caused NameError and NoMethodError.
$ ruby test.rb
test.rb:5:in `<main>': undefined method `foo' for nil:NilClass (NoMethodError)
who_failed = a.foo & b.foo & c.foo
^^^^
$ ruby -v
ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x86_64-linux]
Updated by mame (Yusuke Endoh) about 2 years ago
- Status changed from Open to Rejected
I close this ticket. If you have any opinion, please let me know.