Question

I’m trying to learn some ruby. Imagine I’m looping and doing a long running process, and in this process I want to get a spinner for as long as necessary.

So I could do:

a=['|','/','-','\\'] aNow=0 # ... skip setup a big loop print a[aNow] aNow += 1 aNow = 0 if aNow == a.length # ... do next step of process print '\b' 

But I thought it’d be cleaner to do:

def spinChar   a=['|','/','-','\\']   a.cycle{|x| yield x} end # ... skip setup a big loop print spinChar # ... do next step of process print '\b' 

Of course the spinChar call wants a block. If I give it a block it’ll hang indefinitely.

How can I get just the next yeild of this block?

Answer 1

Ruby’s yield does not work in the way your example would like. But this might be a good place for a closure:

def spinner()   state = ['|','/','-','\\']   return proc { state.push(state.shift)[0] } end  spin = spinner  # start working print spin.call # more work print spin.call # etc... 

In practice I think this solution might be too ‘clever’ for its own good, but understanding the idea of Procs could be useful anyhow.