Recently, I left a comment on one of my colleague’s PR and we had a discussion with him about
the use of try vs the lonely operator &. and it led to a number of conclusions personally.
I used to use lots of .try. I’ve also come across codebases littered with it, be it in the
presentation layer or in the models. From personal experience, I’ll say it’s pretty easy to end up with
.try littered all around.
I was curious about when it shouldn’t be used, and if there were better alternatives.
The Obvious Scenario
Before the lonely operator was introduced, I used try in a 2 distinct scenarios.
The first obvious usecase: when I am not sure if the object that I are calling the method on
could be a nil object or not. Obviously, calling any method on a nil object
rightfully throws an error during runtime. Of course, I could use something like this to avoid the
error.
user && user.name
And user.try(:name) yields the same result.
The Not So Obvious Scenario
Surprisingly, even when I don’t know what the object is and whether it even has that method defined or not,
I still found myself using try. It still returns nil. It’s like this deceivingly good and
lazy way to sidestep NoMethodError. But I find that this laziness, potentially leads to surprises
(which obviously isn’t good).
# Either a guest user without a name, or a registered user with a name
some_user.try(:name)
The Lonely Operator
user&.name is equivalent to user && user.name and only this. It still throws a NoMethodError
when the method doesn’t exist on the object. And that’s good for various reasons.
[]&.invalid_method # throws NoMethodError
In the event where I have no idea what the object is, it is a clear sign that I should spend
the time to refactor the code so that the object class is deterministic and
not rely on a .try to squirm out of the situation.
Another nice side effect is that, the lonely operator really doesn’t look great when I chain it. Being huge on aesthetics and coding styles, I just end up chaining less.
user&.name&.truncate(5) # this just looks clunky imo
All those .try(..).try(..)? I always knew I should be getting rid of those too, but it was just
so safe. Law of Demeter literally screams at me
every time.
I hope this post makes you think twice the next time .try chains comes to mind:P