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From: R.. Kumar 1.9.1 OSX on 30 Jun 2010 07:11
/opt/local/lib/ruby1.9/1.9.1/pathname.rb:270: warning: `*' interpreted
as argument prefix


I keep getting this. I am including highline, sqlite3 and arrayfields in
my code.

I am using ruby -w inside my code.

ruby 1.9.1p376 (2009-12-07 revision 26041) [i386-darwin10]
Mac OSX Intel (Snow leopard).

I get this when running the examples in highline also.
--
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From: Brian Candler on 30 Jun 2010 08:39
R.. Kumar 1.9.1 OSX wrote:
> /opt/local/lib/ruby1.9/1.9.1/pathname.rb:270: warning: `*' interpreted
> as argument prefix

Can you post line 270 of that file, with a few lines of context?

Can you replicate the problem standalone? e.g.

#!/usr/bin/ruby19 -w
require 'pathname'
puts Pathname.new("/etc")

This doesn't give any warning for me, but does it for you? If not,
what's the smallest program you can make which shows the warning?
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From: Josh Cheek on 30 Jun 2010 08:50
[Note: parts of this message were removed to make it a legal post.]

On Wed, Jun 30, 2010 at 6:11 AM, R.. Kumar 1.9.1 OSX <sentinel1879(a)gmail.com
> wrote:

> /opt/local/lib/ruby1.9/1.9.1/pathname.rb:270: warning: `*' interpreted
> as argument prefix
>
>
> I keep getting this. I am including highline, sqlite3 and arrayfields in
> my code.
>
> I am using ruby -w inside my code.
>
> ruby 1.9.1p376 (2009-12-07 revision 26041) [i386-darwin10]
> Mac OSX Intel (Snow leopard).
>
> I get this when running the examples in highline also.
> --
> Posted via http://www.ruby-forum.com/.
>
>
It is a warning to let you know that it considers what you typed to be
ambiguous, and it is concerned that the way it interprets your code may not
be what you intended

ary = [ 10 , 20 , 30 ]

ary.first * 2 # => 20
(ary.first) * 2 # => 20
(ary.first) * (2) # => 20
(ary.first * 2) # => 20
(ary.first * 2) # => 20
ary.first.*(2) # => 20


ary.first *2 # => [10, 20] # !> `*' interpreted as argument prefix
ary.first *[2] # => [10, 20] # !> `*' interpreted as argument prefix
ary.first(*[2]) # => [10, 20]
ary.first(*2) # => [10, 20]
ary.first(2) # => [10, 20]
ary.first 2 # => [10, 20]


In particular notice the first from each set
ary.first * 2 # => 20
ary.first *2 # => [10, 20] # !> `*' interpreted as argument prefix

-----

In your particular case, it sees:

# Return a pathname which is substituted by String#sub.
def sub(pattern, *rest, &block)
if block
path = @path.sub(pattern, *rest) {|*args|
begin
old = Thread.current[:pathname_sub_matchdata]
Thread.current[:pathname_sub_matchdata] = $~
eval("$~ = Thread.current[:pathname_sub_matchdata]",
block.binding)
ensure
Thread.current[:pathname_sub_matchdata] = old
end
yield *args
}
else
path = @path.sub(pattern, *rest)
end
self.class.new(path)
end

and it is worried about the ambiguity of yield *args (get the results of the
block and multiply it by the variable named args vs take the variable args,
invoke the * on it to turn it into a sort of variable argument list, and
then pass those arguments to in to the block)

Anyway, if it bothers you, you can go put parens around it so it becomes
yield(*args) and is not ambiguous. But you don't need to worry about it,
look where it got those args from:
path = @path.sub(pattern, *rest) {|*args|

So it is recursively invoking itself, passing the args through the calls,
clearly the author did want it to be interpreted this way.

-----

Note: can anyone explain to me what unary * is? I looked in the Pickaxe page
333, and don't see it listed with the other operators. I tried defining *@
as an instance method, and I couldn't define it. I tried locating the method
2.method('*@') and it was undefined. I tried looking at parse.y, and found
tSTAR mlhs_node { $$ = NEW_MASGN(0, $2); } which I suspect defines the
interpreter match for it, but couldn't figure out how to then determine what
happens with this. What is it / where did it come from (is it an object?)

From: Brian Candler on 30 Jun 2010 09:55
Josh Cheek wrote:
> Note: can anyone explain to me what unary * is?

It's just the "splat". AFAIK it's not really an operator and is not
mapped to a method call; it's part of the language syntax.
--
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From: R.. Kumar 1.9.1 OSX on 1 Jul 2010 01:48
Brian Candler wrote:
> R.. Kumar 1.9.1 OSX wrote:
>> /opt/local/lib/ruby1.9/1.9.1/pathname.rb:270: warning: `*' interpreted
>> as argument prefix
>
> Can you post line 270 of that file, with a few lines of context?
>
> Can you replicate the problem standalone? e.g.
>
#!/usr/bin/ruby19 -w
require 'pathname'

The above is enough to give the error.

1. I do not want to fix the problem in my own copy of ruby 1.9 and have
it keep returning when i upgrade versions, or have others get it.

2. While googling, I found that the problem was fixed in 1.8.x but
perhaps not in 1.9. Is that the case ?

The code in pathname.rb is

259 # Return a pathname which is substituted by String#sub.
260 def sub(pattern, *rest, &block)
261 if block
262 path = @path.sub(pattern, *rest) {|*args|
263 begin
264 old = Thread.current[:pathname_sub_matchdata]
265 Thread.current[:pathname_sub_matchdata] = $~
266 eval("$~ = Thread.current[:pathname_sub_matchdata]",
block.binding)
267 ensure
268 Thread.current[:pathname_sub_matchdata] = old
269 end
270 yield *args
271 }
272 else
273 path = @path.sub(pattern, *rest)
274 end
275 self.class.new(path)
276 end
--
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