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.

Whenever a block is appended to a method call ruby automatically converts it to a proc object but one without an explicit name. Break is only valid within a block. The method however has a way to access this proc by means of the yield statement. Returning in blocks overwrites outside return values for an example.

Because ruby allows implicit block passing you can call all methods with a block. Def my method value yield puts value is. Syntax collection collection collect the collect method need not always be associated with a block. The collect iterator returns all the elements of a collection.

So in other words the value that yield returns is the value the block returns. In the last form an array of the given size is created. The following code returns the value x y. The value is stored in the variable i and then displayed on the screen.

A ruby block is useful because it allows you to save a bit of logic code use it later. Implicit block passing works by calling the yield keyword in a method. This works exactly like the each method for an array object with one crucial difference. Value end my method do 2 end value is 2.

It finds and calls a passed block so you don t have to add the block to the list of arguments the method accepts. 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. It returns each value of the array one by one to the block. If it doesn t call yield the block is ignored.

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. Methods return the value of the last statement executed. The yield keyword is special. Def do something with block return no block given unless block given.

For a hash you create two elements one for the hash key and one for the value. See fun with ruby. It lets you jump out of a block and returns nil or the provided argument to. Thus the code above prints out 1.

Yield returns the last evaluated expression from inside 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. So far in our two examples above we did not do anything with the return values of the block. Break within a block.

Return has no special meaning in blocks but it can be misunderstood as return from block which is wrong.