In Ruby, symbols are identifiers that start with a colon (:symbol). When you use a hyphen in an unquoted symbol like
:data-role, Ruby interprets the hyphen as a subtraction operator instead of part of the symbol name.
This means Ruby tries to subtract the variable role from the variable data, which typically results in an "undefined
variable" error since these variables don’t exist.
The problem stems from Ruby’s parsing rules: unquoted symbols can only contain letters, numbers, underscores, and certain special characters.
Hyphens are not allowed because they conflict with the subtraction operator.
What is the potential impact?
This issue causes immediate syntax errors that prevent the application from running. The error messages can be confusing to developers, especially
beginners, as they mention "undefined variable" rather than explaining the symbol syntax problem.
In development, this leads to:
- Application crashes with cryptic error messages
- Wasted debugging time trying to understand why variables are "undefined"
- Frustration for developers learning Ruby
The impact is typically caught early since the code won’t run, but it can slow down development and create confusion about proper Ruby syntax.
