Ruby has strict scoping rules that determine where variables and methods can be accessed. Local variables are only accessible within the scope
where they are defined, and method definitions create new scopes.
When code attempts to reference a local variable that doesn’t exist in the current scope, Ruby will raise a NameError at runtime. This
commonly happens in two scenarios:
Local variables assigned in one method but referenced in another: In Ruby, local variables are scoped to the method where they are
defined. Assigning current_user = user inside a method creates a local variable that cannot be accessed from other methods.
Local variables referenced across scope boundaries: Method definitions create new scopes, so local variables defined outside a
method are not accessible within that method. This is different from some other languages where inner scopes can access outer scope variables.
Ruby’s method call syntax can make this confusing because method calls don’t require parentheses. When Ruby encounters an undefined identifier, it
first checks for local variables, then looks for method calls. If neither exists, it raises a NameError.
These scoping violations indicate a misunderstanding of Ruby’s variable accessibility rules and often suggest that the code needs to be
restructured to use appropriate mechanisms for sharing data between different parts of the program.
What is the potential impact?
This issue will cause NameError exceptions at runtime, leading to application crashes. The error may not be discovered until the
specific code path is executed, potentially causing failures in production environments. This can result in poor user experience and system
reliability issues.
