Blocks and Yield

In the last section, we've defined how to create functions. Some blocks in Orange support a simpler form for providing a value. These are called short blocks, and instead of wrapping statements in curly braces, they're just formed by a semi-colon and then any statement or expression.

Our addTwoNumbers function from earlier could be re-written in this short block form:

def addTwoNumbers(a: int, b: int) -> int: a + b

// alternatively:
def addTwoNumbers(a: int, b: int): a + b

// alternatively:
def addTwoNumbers(a: int, b: int): return a + b

// alternatively:
def addTwoNumbers(a: int, b: int): yield a + b

This short-form syntax can be used in any place where statements can occur (functions, for loops, conditionals, etc). More information on rules will be given when we describe those components.

Yield

Note that the last example of our short-block addTwoNumbers function referenced the keyword yield. When using short blocks, the statement or expression provided will be passed through a yield by default.

A yield is a context-sensative keyword that exits out of the current block with the value provided. Like return, a yield can supply nothing and its type would be void.

When yield is used at the highest scope of a function, it acts the same as a return would.

Scoped Blocks

A block is also a valid expression in Orange, which defines a new scope. These scoped blocks can also yield values that can be used as part of an expression. For example:

var myAge = {
    var currentYear = 2016
    var birthYear = 1925
    yield currentYear - birthYear
}

// currentYear and birthYear are out of scope now

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