September 11 2010 4 minute read tags.
Ruby set variable to nil.
Just like any other ruby object nil has a set of methods.
And even those speaking ruby quite fluently don t usually know the tiny little details.
Uninitialized instance variables have the value nil and produce warnings with the w option.
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.
In 99 of the cases if a local variable is missing you have a typo or someone forgot to declare that variable.
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.
There are plenty of options available.
Global variable in class1 is 10 global variable in class2 is 10 ruby instance variables.
By default this variable seems to be set to nil.
Instance variables can change from object to object.
Let s evaluate their usefulness and potential problems that they bring to the table.
However if string split s first argument is nil it will replace it with a single space string.
Memoirs of a software team leader read more.
I think it s more object oriented especially in a language like ruby where everything is an object and message exchange.
Set implements a collection of unordered values with no duplicates.
Do stuff when variable is nil end however i believe that the latter is a better option for two reasons.
This is a hybrid of array s intuitive inter operation facilities and hash s fast lookup.
What about instance variables.
Instance variables are available across methods for any specified instance or object i e.
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.
However all this variable does is act as the default value for the first argument to string split.
Here is an example showing the usage of instance variables.
There is no need to initialize the instance variables and uninitialized instance variable always contains a nil value.
Set is easy to use with enumerable objects implementing each most of the initializer methods and binary operators accept generic enumerable objects besides sets and arrays.
Try the safe navigator operator ruby 2 3 which only calls a method if the variable is not nil.
An enumerable object can be converted to set using the to set.
