Feature #6096: Parser tweak - curly braces followed by a coma...

• Status: Rejected
• Assignee: -
• Target version: -

[ddebernardy (Denis de Bernardy)]

It would be sweet if ruby treated curly braces followed by a coma as a hash rather than as a coma:

def foo(bar, baz)
end
=> nil
foo {}, :baz
SyntaxError: (irb):3: syntax error, unexpected ',', expecting $end
foo {}, :baz
^
from /opt/local/bin/irb:12:in `'

I keep forgetting and run into the issue on a regular basis when writing unit tests... aka:

assert_equal {}, do_stuff

[nobu (Nobuyoshi Nakada)]

• Tracker changed from Bug to Feature

[nobu (Nobuyoshi Nakada)]

• Category set to core

[wardrop (Tom Wardrop)]

I agree, that would be nice, especially given that it would work the other way around, e.g. assert_equal do_stuff, {}. However, there are contexts in which a block literal followed by a comma is valid, e.g. var1, var2 = my_method { }, :something

It's just one of the consequences of optional parenthesis combined with the re-use of the curly bracket syntax. In omitting parenthesis, you introduce a lot of ambiguities - this is consistant with operators which also need parenthesis to disambiguate precedence. Ruby allows you to do that (which is nice), but it has consequences such as what you've reported.

So in some ways, your suggestion is akin to suggesting a change is operator precedence. The fix is obviously to wrap your argument in parenthesis, e.g. assert_equal({}, do_stuff). Or otherwise use Hash.new or Hash[], e.g. assert_equal Hash[], do_stuff. Ruby gives you many options.

[mame (Yusuke Endoh)]

• Status changed from Open to Rejected

I agree with Tom.
Considering Tom's code, it is apparently difficult to fix this issue.

--
Yusuke Endoh [e-mail]