Bug #10293: splatting an empty hash in a method invocation sends an argument to the method (should send nothing)

• Status: Closed
• Assignee: nobu (Nobuyoshi Nakada)
• Target version: -
• ruby -v: ruby 2.1.3p242 (2014-09-19 revision 47630) [x86_64-linux]
• Backport: 2.0.0: UNKNOWN, 2.1: REQUIRED

[rits (First Last)]

irb(main):001:0> def foo; end; foo **{}
ArgumentError: wrong number of arguments (1 for 0)

note that splatting an empty array results in no arguments

this behavior is particularly problematic with send (dispatching to different methods)

send method_name, *possibly_empty_arg_list, **possibly_empty_keyarg_hash

one should not have to do

if possibly_empty_keyarg_hash.empty?
receiver.send method_name, *possibly_empty_arg_list
else
receiver.send method_name, *possibly_empty_arg_list, **possibly_empty_keyarg_hash
end

or

possibly_empty_arg_list << possibly_empty_keyarg_hash unless possibly_empty_keyarg_hash.empty?
receiver.send method_name, *possibly_empty_arg_list

[nagachika (Tomoyuki Chikanaga)]

• Category set to core
• Status changed from Open to Assigned
• Assignee set to nobu (Nobuyoshi Nakada)
• Target version set to 2.2.0
• Backport changed from 2.0.0: UNKNOWN, 2.1: UNKNOWN to 2.0.0: UNKNOWN, 2.1: REQUIRED

[rits (First Last)]

https://bugs.ruby-lang.org/issues/9291 is somewhat related
foo(**nil) should not raise since foo(*nil) does not and it's the more useful behavior

[naruse (Yui NARUSE)]

• Target version deleted (2.2.0)

[jeremyevans0 (Jeremy Evans)]

• Related to Feature #14183: "Real" keyword argument added

[jeremyevans0 (Jeremy Evans)]

• Status changed from Assigned to Closed

With the acceptance of #14183, double splatting an empty hash no longer sends an empty positional hash to the method.