Ruby Return Value From Block

This works exactly like the each method for an array object with one crucial difference.

Ruby return value from block.

Yield returns the last evaluated expression from inside the block. Remember that we said a block returns a value just like methods do. So in other words the value that yield returns is the value the block returns. It lets you jump out of a block and returns nil or the provided argument to.

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. For a hash you create two elements one for the hash key and one for the value. The method however has a way to access this proc by means of the yield statement. Implicit block passing works by calling the yield keyword in a method.

As you can see name is not available to my method because it s local to the block. The value is stored in the variable i and then displayed on the screen. The collect iterator returns all the elements of a collection. 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. It finds and calls a passed block so you don t have to add the block to the list of arguments the method accepts. In the last form an array of the given size is created. The following code returns the value x y.

Because ruby allows implicit block passing you can call all methods with a block. Syntax collection collection collect the collect method need not always be associated with a block. Thus the code above prints out 1. The yield keyword is special.

Returning in blocks overwrites outside return values for an example. Break is only valid within a 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. Each element in this array is created by passing the element s index to the given block and storing the return value.

Methods return the value of the last statement executed. Break within a block. Value end my method do 2 end value is 2. Def my method value yield puts value is.

If it doesn t call yield the block is ignored. A ruby block is useful because it allows you to save a bit of logic code use it later. See fun with ruby. Whenever a block is appended to a method call ruby automatically converts it to a proc object but one without an explicit name.

It returns each value of the array one by one to the block.