Issue #7837 has been updated by nobu (Nobuyoshi Nakada).

Status changed from Open to Rejected

It's common behavior to keyword arguments,

  $ ruby -e 'def foo(a, b, c:1);end' -e 'foo(2,3,42)'
  -e:1:in `foo': wrong number of arguments (3 for 2) (ArgumentError)
  	from -e:2:in `<main>'

The optional argument hash is stripped before arity check, so it's "invisible" as arity.
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Bug #7837: IO.open with three arguments where third argument is bogus reports an arity problem instead of type problem
https://bugs.ruby-lang.org/issues/7837#change-36196

Author: enebo (Thomas Enebo)
Status: Rejected
Priority: Normal
Assignee: 
Category: core
Target version: next minor
ruby -v: ruby 2.0.0dev (2013-02-08 trunk 39161) [x86_64-darwin11.4.2]


I am reporting this against 2.0.rc2 but it also applies to mri 1.9.3.  If I run the following one-liner:

mri20 -e 'f = File.open("tmp"); IO.open(f.fileno, "r", :heh)'

I get the error:

-e:1:in `initialize': wrong number of arguments (3 for 1..2) (ArgumentError)

This seems wrong because if I change the third argument to an options hash it works fine.  So having an arity of 3 is not a problem for open.  It is that :heh is not a hash.  I think this should generate a TypeError.




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