Ruby Return Value From Block

The method select then returns this array and ruby will pass it to the method p which prints the array out to the screen.

Ruby return value from block.

The collect iterator returns all the elements of a collection. The yield keyword is special. This works exactly like the each method for an array object with one crucial difference. A ruby block is useful because it allows you to save a bit of logic code use it later.

Each element in this array is created by passing the element s index to the given block and storing the return value. This concept which is sometimes called closure means that a proc will carry with it values like local variables and methods from the context where it was defined. Remember that we said a block returns a value just like methods do. Break within a block.

So in other words the value that yield returns is the value the block returns. Like the array these elements are placeholders that are used to pass each key value pair into the code block as ruby loops through the hash. Return has no special meaning in blocks but it can be misunderstood as return from block which is wrong. For a hash you create two elements one for the hash key and one for the value.

Methods return the value of the last statement executed. Because ruby allows implicit block passing you can call all methods with a block. It lets you jump out of a block and returns nil or the provided argument to. The following code returns the value x y.

Yield returns the last evaluated expression from inside the block. If it doesn t call yield the block is ignored. As you can see name is not available to my method because it s local to the block. Returning in blocks overwrites outside return values for an example.

So far in our two examples above we did not do anything with the return values of the block. New 3 index index 2 0 1 4 common gotchas when sending the second parameter the same object will be used as the value for all the array. The value is stored in the variable i and then displayed on the screen. Def my method value yield puts value is.

In the last form an array of the given size is created. Break is only valid within a block. The method however has a way to access this proc by means of the yield statement. Whenever a block is appended to a method call ruby automatically converts it to a proc object but one without an explicit name.

Value end my method do 2 end value is 2. See fun with ruby. Thus the code above prints out 1. Implicit block passing works by calling the yield keyword in a method.

Def do something with block return no block given unless block given.