def Binding.of_caller(&block)
old_critical = Thread.critical
Thread.critical = true
count = 0
cc, result, error, extra_data = Continuation.create(nil, nil)
error.call if error
tracer = lambda do |*args|
type, context, extra_data = args[0], args[4], args
if type == "return"
count += 1
if count == 2
set_trace_func(nil)
cc.call(eval("binding", context), nil, extra_data)
end
elsif type == "line" then
nil
elsif type == "c-return" and extra_data[3] == :set_trace_func then
nil
else
set_trace_func(nil)
error_msg = "Binding.of_caller used in non-method context or " +
"trailing statements of method using it aren't in the block."
cc.call(nil, lambda { raise(ArgumentError, error_msg) }, nil)
end
end
unless result
set_trace_func(tracer)
return nil
else
Thread.critical = old_critical
case block.arity
when 1 then yield(result)
else yield(result, extra_data)
end
end
end