I was perusing PHP7's features, and tried some examples of their
enhanced "yield" in Perl6. The first was pretty easy, the second I
haven't figured out. Curious what yinz can do.
Here's the first:
==php==
<?php
function gen()
{
yield 1;
yield 2;
yield from gen2();
}
function gen2()
{
yield 3;
yield 4;
}
foreach (gen() as $val)
{
echo $val, PHP_EOL;
}
?>
The above example will output:
1
2
3
4
===p6=== (Condensed)
sub gen {gather {take 1; take 2;.take for gen2();}}
sub gen2 {gather {take 3; take 4}}
.say for gen;
###
This is the PHP example I'm having trouble doing the equivalent of in Perl6:
==PHP7===
Generator Return Expressions
This feature builds upon the generator functionality introduced into
PHP 5.5. It enables for a return statement to be used within a
generator to enable for a final expression to be returned (return by
reference is not allowed). This value can be fetched using the new
Generator::getReturn() method, which may only be used once the
generator has finishing yielding values.
<?php
$gen = (function() {
yield 1;
yield 2;
return 3;
})();
foreach ($gen as $val) {
echo $val, PHP_EOL;
}
echo $gen->getReturn(), PHP_EOL;
The above example will output:
1
2
3
Being able to explicitly return a final value from a generator is a
handy ability to have. This is because it enables for a final value to
be returned by a generator (from perhaps some form of coroutine
computation) that can be specifically handled by the client code
executing the generator. This is far simpler than forcing the client
code to firstly check whether the final value has been yielded, and
then if so, to handle that value specifically.
###
-y
