In this example,
def foo(x) if(x > 5) bar = 100 end puts bar end
Then foo(6) Outputs: 100 and foo(3) outputs nothing.
However if i changed the definition to
def foo(x) if(x > 5) bar = 100 end puts bob end
I get an "undefined local variable or method" error.
So my question is why I am not getting this error when I call foo(3) and bar is never set?
Scopes are custom queries that you define inside your Rails models with the scope method. Every scope takes two arguments: A name, which you use to call this scope in your code. A lambda, which implements the query.
To keep track of the current scope, Ruby uses bindings, which encapsulate the execution context at each position in the code. The binding method returns a Binding object which describes the bindings at the current position.
There a couple of things going on here. First, variables declared inside the if
block have the same local scope as variables declared at the top level of the method, which is why bar
is available outside the if
. Second, you're getting that error because bob
is being referenced straight out of the blue. The Ruby interpreter has never seen it and never seen it initialized before. It has, however, seen bar
initialized before, inside the if statement. So when is gets to bar it knows it exists. Combine those two and that's your answer.
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