Map with &:method_name

Ruby
1

I see this a lot but it doesn’t work for me in IRB. Is a gem required or
something?

[1,2,3].map(&:to_s)
TypeError: wrong argument type Symbol (expected Proc)
from (irb):2

2

On Jul 10, 2008, at 3:11 PM, Oliver S. wrote:

I see this a lot but it doesn’t work for me in IRB. Is a gem
required or
something?

[1,2,3].map(&:to_s)
TypeError: wrong argument type Symbol (expected Proc)
from (irb):2

it’s rails - basically

class Symbol
def to_proc
sym = self
lambda{|obj| obj.send sym}
end
end

a @ http://codeforpeople.com/

3

On Thu, Jul 10, 2008 at 5:22 PM, ara.t.howard [email protected]
wrote:

end

And it’s been picked up in Ruby 1.9, and maybe 1.8.7 as well since the
current draft of the Pickaxe 3rd ed doesn’t label it as 1.9 only.

–
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/

4

ara.t.howard wrote:

On Jul 10, 2008, at 3:11 PM, Oliver S. wrote:

I see this a lot but it doesn’t work for me in IRB. Is a gem
required or
something?

[1,2,3].map(&:to_s)
TypeError: wrong argument type Symbol (expected Proc)
from (irb):2

it’s rails - basically

class Symbol
def to_proc
sym = self
lambda{|obj| obj.send sym}
end
end

a @ http://codeforpeople.com/

OK thanks guys. I found the actual definition:

class Symbol
def to_proc
Proc.new { |*args| args.shift.send(self, *args) }
end
end