Add allowDuplicates option to randomElements()

[vlakoff]

• "dice rolls" instead of "raffle tickets".
• can also be useful to pick more elements than the array length.

$faker->randomElements(['foo', 'bar', 'baz', 'qux'], 3, true);

// possible result: 'foo', 'bar', 'foo'

[fzaninotto]

Isn't it the purpose of the unique() modifier?

[vlakoff]

That's precisely the contrary. Currently randomElements() forces keys to be picked only once, and I'm adding an option to disable this unicity constraint.

In fact the unique() modifier is completely unrelated to this, as it operates on the provider results.

[fzaninotto]

OK, now I get you. then you should change the default behavior to allow duplicates, and remove the allowDuplicates options (the user can already do that with unique()).

[vlakoff]

But another confusion, these are two different things:

• Picking several times the same element from the input array (this PR)
• Having identical selections returned by randomElements() (unique modifier)

Also, changing the default mode would definitely be a BC break.

[fzaninotto]

I'm OK for a small BC break for this. And I don't get your first point.

[vlakoff]

Maybe a bit of code would help to understand that unique() is unrelated:

$data = ['foo', 'bar', 'baz', 'qux'];

// can give ['foo', 'bar']
// but not ['foo', 'foo']
$faker->randomElements($data, 2);

// assume this returned ['foo', 'bar']...
$faker->unique()->randomElements($data, 2);
// ... this can't return ['foo', 'bar'] too.
$faker->unique()->randomElements($data, 2);

unique() enforces the same serialized data can't be returned several times. So here, the same selection of elements, and in the same order.

[vlakoff]

And I disagree about changing the default mode:

• There is no preferable mode, so why introducing an unneeded BC break?
• PHP's array_rand() also doesn't return duplicates.
• Avoiding duplicates shouldn't have many side effects, whereas getting several times the same element could be unexpected and break some apps. So it sounds fine having to explicitly enable duplicates.

[fzaninotto]

OK, you've convinced me.

[fzaninotto]

Thanks!