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

rubyonrails-talk
1

I have a function that is defined as such:

def rubyfunc( &block )     ... end

Its called by "interface.rubyfunc" (Where obviously interface is a class)

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?

2

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 end

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

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

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

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

rubyfunc{ puts 'hello' }

-K

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