Pattern for methods and properties

[Manaus]

I cannot grasp the pattern behind the object method/properties:

$page->hasChildren() // or $page->hasChildren ?
$page->id(); // or $page->id ?
$children->count() // or $children->count ?

I mean, when to use parentheses, and when not? Is there a principle behind this?

Usually after a couple of attempts I manage to get it working, but I'd like to have the idea come natural, without thinking.

Thank you very much

 

[pwired]

Not sure what you mean by pattern ...
I think it needs an extra pair of surrounding Parentheses ... if($page->hasChildren())

 

[MarkE]

Methods have parentheses, properties do not. Check the API reference if you are not sure. 

[bernhard]

You don't know what to use when because ProcessWire does some magic here to make both versions work most of the time. For example the method to get children of the current page is $page->children() (https://processwire.com/api/ref/page/children/) but $page->children will work as well.

ProcessWire does that using magic methods (https://www.php.net/manual/en/language.oop5.magic.php) so when you request $page->children it will check if a method "children" exists and will call that method for you even though you are accessing it as a property and not as a method.

So requesting the method directly might be slightly more efficient, but in most cases I guess it will not matter. And imho using the "property syntax" like $this->wire->files->render() is cleaner than always using methods. $this->wire()->files()->render()...

[bernhard]

4 hours ago, Manaus said:

I mean, when to use parentheses, and when not? Is there a principle behind this?

Usually methods do something and properties hold a value. So $pages->count() would be a method whereas $page->id would access the id property of the page object...