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 geeks puts "In the geeks method" # using yield keyword yield puts "Again back to the geeks method" yield end geeks {puts "This is block" } |
Output:
In the geeks method This is block Again back to the geeks 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 geeks_for_geeks = yield puts geeks_for_geeks end yield_with_return_value { "Welcome to geeksforgeeks" } |
Output:
Welcome to geeksforgeeks
The geeks_for_geeks variable get the “Welcome to geeksforgeeks” returned by the block and display it by using puts.
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