HasX

HasX is a naming convention used in software design to denote the presence or support of a capability X within an object, component, or system. It typically manifests as a boolean property, a predicate method, or a feature flag. The interpretation of hasX depends on the language and architecture: it may appear as a field on a data object (hasX: boolean), as a method that returns a boolean (hasX()), or as part of a configuration that signals feature support.

In practice, hasX is used to perform quick checks before attempting operations that assume a capability exists. For example, a device object might expose hasNFC to indicate NFC capability, and code can branch accordingly. In APIs, an object may expose hasX to communicate support for a feature without fully exposing the feature itself, aiding simple feature detection.

Design considerations include readability and ease of use, since hasX can make capability checks explicit. However, it can introduce redundancy if the feature is always present or if capabilities evolve without corresponding updates. It may also obscure how features are implemented, potentially leading to tight coupling. Therefore, hasX is often used in conjunction with other patterns such as explicit capability interfaces, optional properties, or separate service discovery mechanisms.

Variants and related terms include similar patterns such as supportsX and canX. In data schemas or configuration, a boolean hasX field is commonly used to model capabilities, though some architectures prefer capability-based design or feature flags to manage dynamic availability. See also feature flags, capability-based design, and predicate methods.