Ruby Set Variable If Nil

For many beginning rubyists especially those having experience in other programming languages such as java or c checking whether variable is nil may seem a little bit confusing.

Ruby set variable if nil.

Foo nil so watch out for that it might just happen that you misspelt the name of your instance variable or you forgot to initialize it. Try the safe navigator operator ruby 2 3 which only calls a method if the variable is not nil. And even those speaking ruby quite fluently don t usually know the tiny little details. Is the a more succinct way of expressing the above.

In 99 of the cases if a local variable is missing you have a typo or someone forgot to declare that variable. It is more readable in my subject opinion even if it is less compact. In ruby on rails what s the difference actually. Just like any other ruby object nil has a set of methods.

I need to set it if the variable is nil or empty 0 length string. This spread to freenode s awesome ruby lang irc channel where. Uninitialized instance variables have the value nil and produce warnings with the w option. Variable id if variable nil.

Undefined instance variables are always nil so you want to check for that. Here is an example showing the usage of instance variables. Let s evaluate their usefulness and potential problems that they bring to the table. I ve come up with the following.

Do stuff when variable is nil end however i believe that the latter is a better option for two reasons. Global variable in class1 is 10 global variable in class2 is 10 ruby instance variables. There are plenty of options available. Instance variables begin with commat.

I have a show page for my users and each attribute should only be visible on that page if it is not nil and not an empty string. I think it s more object oriented especially in a language like ruby where everything is an object and message exchange. In rubyists already use monadic patterns dave fayram made a passing reference to using to set a variable s value if its value were nothing false or nil in ruby. Variable empty while it works it doesn t seem very ruby like to me.

You should be aware that undefined instance variables will return nil. Memoirs of a software team leader read more. What about instance variables. The resulting reddit quickly picked up on his definition which was fixed later and argued about s true meaning which isn t as obvious as many rubyists think.

I am not too familiar with creating my own methods but can i somehow create a shortcut to do something like this.