What does the ' & ' mean when associated to a block?

I have a function that is defined as such:

def rubyfunc( &block )


Its called by “interface.rubyfunc” (Where obviously interface is a

Can anyone give me an explanation of what the “&”-sign is and in general
what the parameter is when I call it from an empty function?

the syntax of ‘&’ comes from the c/c++ lang and means that the variable
‘block’ is not a parameter in the normal list.

‘block’ would take a ruby variable

while ‘&block’ takes a block of code

The function would be called like this

rubyfunc do |some_param|
puts param.to_s

where the do/end is becomes a Proc object and gets stored in the &block

& must be used on the last argument in the function definition.

An instance of a Proc object can be executed via <var_name>.call()

note that the do/end can be substituted with {} but should only be used
on single line blocks ie.

rubyfunc{ puts ‘hello’ }


p.s. this is a ruby syntax question and should be posted on the ruby
forum in the future.