Ruby Set Variable If Nil

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

Ruby set variable if nil.

Undefined instance variables are always nil so you want to check for that. Here is an example showing the usage of instance variables. 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. I m trying to set a variable conditionally in ruby.

Global variable in class1 is 10 global variable in class2 is 10 ruby instance variables. Below i have my controller and it is quite annoying having to write the same line of code user city nil user city for every variable. In 99 of the cases if a local variable is missing you have a typo or someone forgot to declare that variable. In ruby on rails what s the difference actually.

Variable empty while it works it doesn t seem very ruby like to me. I need to set it if the variable is nil or empty 0 length string. I ve come up with the following. Let s evaluate their usefulness and potential problems that they bring to the table.

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. What about instance variables. September 11 2010 4 minute read tags. And even those speaking ruby quite fluently don t usually know the tiny little details.

This spread to freenode s awesome ruby lang irc channel where. Is the a more succinct way of expressing the above. Instance variables begin with commat. Variable id if variable nil.

Uninitialized instance variables have the value nil and produce warnings with the w option. There are plenty of options available. 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. 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.

Do stuff when variable is nil end however i believe that the latter is a better option for two reasons. You should be aware that undefined instance variables will return nil. It is more readable in my subject opinion even if it is less compact. I think it s more object oriented especially in a language like ruby where everything is an object and message exchange.

Try the safe navigator operator ruby 2 3 which only calls a method if the variable is not nil.