CapWords

CapWords is a naming convention in which a single compound identifier is written without spaces or separators, and each word in the name begins with a capital letter. It is essentially the same as PascalCase, and is sometimes used interchangeably with CamelCase, though some style guides distinguish CamelCase as starting with a lowercase first word (lowerCamelCase) and CapWords/PascalCase as starting with an uppercase first word.

In Python, CapWords is the standard convention for class and exception names. The Python Enhancement Proposal 8 (PEP 8) describes class names using CapWords, with examples such as HttpRequest, JsonResponse, and ValueError. This contrasts with the snake_case style typically used for functions, methods, and variables. The distinction helps signal the role of an identifier within code: types and construction-related entities often use CapWords, while operations and data attributes use underscores and lowercase words.

Beyond Python, the general idea appears in several languages that favor CamelCase or PascalCase for type names and constructors. Java and C# commonly use PascalCase for classes and interfaces, whereas some JavaScript coding styles reserve CamelCase for constructor functions and React components, with regular functions leaning toward camelCase. The exact rules vary by language and project, but the core goal remains the same: improve readability by clearly delimiting word boundaries in compound identifiers.

Overall, CapWords serves as a recognizable, language-appropriate convention for naming types and built-in constructs, promoting consistency and readability in codebases that adopt it.