What is the difference between calling .first and .first()?

Question

So here's something I've never been able to figure out about Twig. Does it make a difference if you include the parenthesis for functions or not?

In other words, what is the difference – if any – between calling

craft.entries.first

and

craft.entries.first()

?

Answer 1

I think it was Ben Croker who mentioned this nugget from the Twig docs in his Craft course on development:

For convenience's sake foo.bar does the following things on the PHP layer:

• check if foo is an array and bar a valid element;
• if not, and if foo is an object, check that bar is a valid property;
• if not, and if foo is an object, check that bar is a valid method (even if bar is the constructor - use __construct() instead);
• if not, and if foo is an object, check that getBar is a valid method;
• if not, and if foo is an object, check that isBar is a valid method;
• if not, return a null value.

foo['bar'] on the other hand only works with PHP arrays:

• check if foo is an array and bar a valid element;
• if not, return a null value.

The more you find out about Twig, the more you don't know!

Answer 2

On a more philosophical note; Put yourself in the shoes of first(). It's a method, doing an important job in the Craft eco-system. It prides itself on returning the most important and relevant data in an efficient and unencumbered way. Serving up entry after entry, asset after asset, 24 hours a day, all week, all year. Never complaining, never getting any praise.

And you want to treat it like a simple property? As a dumb, brainless reference to some data that some other method created? How do you think that makes first() feel? How would you feel if someone treated you as property?

I know you're a good person with a big heart, Mats. I'm sure you will do the right thing and treat first() with the respect it deserves, even though it means that you'll have to write a few more characters a day.

Answer 3

There is absolutely no difference. Twig will recognize a method without parenthesis as simply being a method without parameters.

The only "gotcha" is if you also happen to have a property by the same name in your class. It's probably a bad idea to do so anyway, but if you have a method & property sharing the same name, Twig will parse the parenthesis-less name as the property value instead.