Ruby Return Value From Block

It finds and calls a passed block so you don t have to add the block to the list of arguments the method accepts.

Ruby return value from block.

Syntax collection collection collect the collect method need not always be associated with a block. For a hash you create two elements one for the hash key and one for the value. Implicit block passing works by calling the yield keyword in a method. Yield returns the last evaluated expression from inside the block.

So in other words the value that yield returns is the value the block returns. The method select then returns this array and ruby will pass it to the method p which prints the array out to the screen. 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. So far in our two examples above we did not do anything with the return values of the block.

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. A ruby block is useful because it allows you to save a bit of logic code use it later. See fun with ruby. Return has no special meaning in blocks but it can be misunderstood as return from block which is wrong.

The method however has a way to access this proc by means of the yield statement. If it doesn t call yield the block is ignored. Each element in this array is created by passing the element s index to the given block and storing the return value. Break is only valid within a block.

Remember that we said a block returns a value just like methods do. Def do something with block return no block given unless block given. It returns each value of the array one by one to the block. The collect iterator returns all the elements of a collection.

It lets you jump out of a block and returns nil or the provided argument to. Break within a block. Value end my method do 2 end value is 2. 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. Thus the code above prints out 1. 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. Def my method value yield puts value is.

Returning in blocks overwrites outside return values for an example. The yield keyword is special. Methods return the value of the last statement executed. 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.