Documentation
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Overview ¶
Package unparam provides helpers for generating nolint comments for the unparam linter (mvdan.cc/unparam), which flags a function parameter (or result) that never varies across its call sites.
unparam's default remediation - delete the parameter and inline the constant value at its one effective use - is usually right, and is a real simplification rather than linter appeasement. But unparam cannot see that a signature is fixed by something other than its own call sites: an interface method set, a function-type variable (http.HandlerFunc, sort.Interface, a callback field), or an exported API whose signature is a compatibility contract. In those cases the parameter is genuinely unused today, but removing it isn't possible (or isn't safe) without breaking the thing the signature exists to satisfy - nolint is the correct call.
Usage ¶
comment := unparam.Nolint(unparam.CommonReasons.InterfaceSignature) // Returns: "//nolint:unparam // Signature fixed by an interface method // set this type implements"
When to fix instead of nolint ¶
Reach for the real fix first - delete the parameter and hardcode the constant inside the function body - whenever the signature isn't externally constrained. This is especially common in test helpers, where a parameter added for generality often ends up receiving the same value at every call site as the test suite grows. See CommonReasons for the constrained-signature cases nolint is actually for.
Index ¶
Constants ¶
This section is empty.
Variables ¶
var CommonReasons = struct { // InterfaceSignature is for a method whose parameter list is fixed by // an interface it implements (e.g. sort.Interface, io.Writer, // database/sql/driver.Valuer) even though this particular // implementation doesn't use every parameter. InterfaceSignature string // CallbackSignature is for a function passed as a value where the // signature is fixed by the receiving API (http.HandlerFunc, a // third-party callback/hook type, a function-type struct field) rather // than chosen by this function itself. CallbackSignature string // ExportedAPICompat is for an exported function or method whose // signature is a compatibility contract: removing a currently-unused // parameter would be a breaking change for callers outside this // module, even though no internal call site varies it today. ExportedAPICompat string }{ InterfaceSignature: "Signature fixed by an interface method set this type implements", CallbackSignature: "Signature fixed by the callback/function type this value is passed as", ExportedAPICompat: "Parameter kept for exported API compatibility; removing it would be a breaking change for external callers", }
CommonReasons provides pre-written reason strings for common scenarios where a parameter or result unparam flags as unused is actually required by something outside the function's own call sites.
Functions ¶
Types ¶
This section is empty.
Source Files