reachwhile

Reachwhile is a term used in computing and systems engineering to describe a control construct that combines reachability checks with a looping execution. It is not a standardized language feature; its exact form and semantics vary by domain and library.

Origin and concept: The name is a portmanteau of reach and while. In general, a reachwhile construct repeats a block of code while the system remains in a transitioning state toward a target or until a reach condition becomes true. The idea is to couple progress toward a goal with ongoing evaluation of reach criteria, rather than treating the target alone as a simple condition.

Usage and examples: In robotics, a reachwhile loop may issue motion commands toward a target pose while polling sensors; the loop ends when the target is reached within a specified tolerance or when safety constraints require an exit. In software and networks, reachwhile can describe retry or recovery patterns that continue until a resource becomes reachable, a connection succeeds, or a timeout occurs. In animation or simulation, it can drive an object along a path while verifying that intermediate milestones are achieved before proceeding.

Variants and relation to other constructs: Semantics differ across implementations. Some variants exit as soon as the target becomes reachable, others require stability or repeated confirmation. Related ideas include while loops, until constructs, reachability checks, and event-driven progress patterns. Some libraries label similar patterns as reach-to or reach-and-hold, reflecting domain-specific emphasis.

See also: while loop, reachability, retry loop, event-driven programming. Note that practical definitions of reachwhile depend on the domain, so documentation should be consulted for a given library or framework.