Simple Explanation of Yield in Ruby

Yield meaning in ruby

the yield keyword is used inside methods for calling a block which is a bit of code enclosed in do/end keywords or curly brackets {}.
we have to understand blocks well in order to understand the yield keyword and what does it do.
this article assumes the reader has a good understanding of ruby blocks.
so the yield keyword is basically telling the method to stop executing the code in this method, and instead execute the code in this block. then, return to the code in the method.

here is an example:

def yield_example
  puts "the program is now executing the code inside this method"
  yield
  puts "now we are back in the method after executing the block"
end

Now to call this method with a block, we use the name of the method and append the block:

yield_example { puts "the method has yielded our block!" }

Or we can do this

yield_example do
  puts "the method has yielded our block!"
end

Now When we call the #yield_example method with the above block, the output will be:

the program is now executing the code inside this method
the method has yielded our block!
now we are back in the method after executing the block

Note that If we call yield without having a block, then we will get an error.
Here is an example:

def yield_example
  yield
end

yield_example

# LocalJumpError: no block given (yield)

To avoid that we can do this

def yield_example
  yield if block_given?
end

The block_given? method checks if a block is available and this will allow us to only yield if the block is given.

Conclusion

This was a simple explanation of yield in ruby and there is more to it than that so check out this on stackoverflow
and Ruby-doc for more information.