HANDSONLABS SOFTWARE ACADEMY

Correspondingly to the argument type statements, give type statements that indicate the type of output to be brought back from a methods. Noteworthy, is that fact that similar types are put back as results for return type declarations and presently for argument type statements.

For instance:

</pre>

<?php class Item { private $id; public function __construct(int $id) { $this->id = $id;
}
public function id() : int
{
return $this->id;
}
}
class Collection {
private $items = [];
public function __construct(Item ...$items)
{
$this->items = $items;
}
public function item() : Generator
{
yield from $this->items;
}
}
$items = [];
for ($i=0; $i<10; $i++) { $items[] = new Item($i); } $collection = new Collection(...$items); $generator = $collection->item();
printf("\nThe Collection::item() method returns a type of %s, as expected\n", get_class($generator));
printf("However, it yields the following:\n\n");
foreach ($generator as $item) {
printf("\tClass: %s. Calling id() method returns %d (%s)\n", get_class($item), $item->id(), gettype($item->id()));
}
printf("\n\nIt doesn't appear to be possible to hint the yielded type\n\n");

?>
<pre>

Output:

The Collection::item() method returns a type of Generator, as expected However,
it yields the following: Class: Item. Calling id() method returns 0 (integer) Class:
Item. Calling id() method returns 1 (integer) Class: Item. Calling id() method returns 2 (integer) Class:
Item. Calling id() method returns 3 (integer) Class: Item. Calling id() method returns 4 (integer) Class:
Item. Calling id() method returns 5 (integer) Class: Item. Calling id() method returns 6 (integer) Class:
Item. Calling id() method returns 7 (integer) Class: Item. Calling id() method returns 8 (integer) Class:
Item. Calling id() method returns 9 (integer) It doesn’t appear to be possible to hint the yielded type

SourceCode Courtesy: Antnee

What must be noted here is that PHP 7 now permits developers to create a return type dynamically. In the above code by github/Antnee, Collection::item()  will not appear to be executing any task (particularly if there’s no return statement, but the resultant Item type. Therefore, the resultant type in Collection::item with reference to the Item.

ABOUT THE AUTHOR

About the Author: Oluwatobi Owoeye has over seventeen years’ experience in Computer Systems and Technologies with several evidence based results. He has worked in several Information Technology projects. A published Author and currently specializing in Robotics & Mobile Computing: Analytics, Computer Vision, Distributed & Parallel Computing, and Machine Learning.

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