Ruby Return Value From Block

So in other words the value that yield returns is the value the block returns.

Ruby return value from block.

Yield returns the last evaluated expression from inside the block. The yield keyword is special. Value end my method do 2 end value is 2. If it doesn t call yield the block is ignored.

In the last form an array of the given size is created. It returns each value of the array one by one to the block. Remember that we said a block returns a value just like methods do. The following code returns the value x y.

Def do something with block return no block given unless block given. 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. A ruby block is useful because it allows you to save a bit of logic code use it later. It lets you jump out of a block and returns nil or the provided argument to.

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. Methods return the value of the last statement executed. Because ruby allows implicit block passing you can call all methods with a block.

The value is stored in the variable i and then displayed on the screen. Syntax collection collection collect the collect method need not always be associated with a block. Break is only valid within a block. 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. Break within a block. For a hash you create two elements one for the hash key and one for the value. Each element in this array is created by passing the element s index to the given block and storing the return value.

Implicit block passing works by calling the yield keyword in a method. Whenever a block is appended to a method call ruby automatically converts it to a proc object but one without an explicit name. This works exactly like the each method for an array object with one crucial difference. It finds and calls a passed block so you don t have to add the block to the list of arguments the method accepts.

The method select then returns this array and ruby will pass it to the method p which prints the array out to the screen. Thus the code above prints out 1. Returning in blocks overwrites outside return values for an example. As you can see name is not available to my method because it s local to the block.

The collect iterator returns all the elements of a collection.