Ruby Set Variable If Nil

Just like any other ruby object nil has a set of methods.

Ruby set variable if nil.

Here is an example showing the usage of instance variables. I think it s more object oriented especially in a language like ruby where everything is an object and message exchange. Variable empty while it works it doesn t seem very ruby like to me. September 11 2010 4 minute read tags.

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. Variable id if variable nil. What about instance variables.

In ruby on rails what s the difference actually. Global variable in class1 is 10 global variable in class2 is 10 ruby instance variables. Memoirs of a software team leader read more. Uninitialized instance variables have the value nil and produce warnings with the w option.

Undefined instance variables are always nil so you want to check for that. Instance variables begin with commat. Let s evaluate their usefulness and potential problems that they bring to the table. 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 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. It is more readable in my subject opinion even if it is less compact. 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. 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 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. You should be aware that undefined instance variables will return nil. Try the safe navigator operator ruby 2 3 which only calls a method if the variable is not nil. This spread to freenode s awesome ruby lang irc channel where.

I need to set it if the variable is nil or empty 0 length string. And even those speaking ruby quite fluently don t usually know the tiny little details. 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 m trying to set a variable conditionally in ruby.

There are plenty of options available.