The yield Keyword in Ruby
We can send a block to our method and it can call that block multiple times. This can be done by sending a proc/lambda, but is easier and faster with yield. During a method invocation The yield keyword in corporation with a block allows to pass a set of additional instructions. When yield is called in side a method then method requires a block with in it. A block is simply a chunk of code, and yield allows us to inject that code at some place into a method.
Simple Yield: When the yield keyword used inside the body of a method, will allow us to call that method with a block of code. Below is simple yield program to understand.
# Ruby program of using yield keyword def Beginner puts "In the Beginner method" # using yield keyword yield puts "Again back to the Beginner method" yield end Beginner {puts "This is block" } |
Output:
In the Beginner method This is block Again back to the Beginner method This is block
Yield with argument: Below is the program of yield with argument.
# Ruby program of using yield keyword # with argument def gfg yield 2 * 3 puts "In the method gfg" yield 100 end gfg {|i| puts "block #{i}" } |
Output :
block 6 In the method gfg block 100
In above example, the yield statement is written followed by parameters. we can even pass more than one parameter after yield. To accept the parameters we placed a variable(i) between two vertical lines (||).
Yield with Return value: It is possible to get the return value of a block by simply assigning the return value of a yield to a variable. if we use yield with an argument, it will pass that argument to the block.
# Ruby program of using yield keyword # with return value def yield_with_return_value Beginner_for_Beginner = yield puts Beginner_for_Beginner end yield_with_return_value { "Welcome to w3wiki" } |
Output:
Welcome to w3wiki
The Beginner_for_Beginner variable get the “Welcome to w3wiki” returned by the block and display it by using puts.