overriding #call in the singleton class of a Proc, a bad idea in the first place, but also:

gistfile1.txt

ruby-1.9.2-p290 :030 > a = proc{'eh'}
 => #<Proc:0x000001009ac850@(irb):30> 
ruby-1.9.2-p290 :031 > a.()
 => "eh" 
ruby-1.9.2-p290 :032 > a[]
 => "eh" 
ruby-1.9.2-p290 :033 > a.call
 => "eh" 
ruby-1.9.2-p290 :034 > def a.call; super + '?'; end
 => nil 
ruby-1.9.2-p290 :035 > a.()
 => "eh?" 
ruby-1.9.2-p290 :036 > a[]
 => "eh" 
ruby-1.9.2-p290 :037 > a.call
 => "eh?" 

Ideas:

• try something similar with a lambda