nixpkgs/lib/meta.nix

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/* Some functions for manipulating meta attributes, as well as the
name attribute. */
let lib = import ./default.nix;
in
rec {
/* Add to or override the meta attributes of the given
derivation.
Example:
addMetaAttrs {description = "Bla blah";} somePkg
*/
addMetaAttrs = newAttrs: drv:
drv // { meta = (drv.meta or {}) // newAttrs; };
/* Change the symbolic name of a package for presentation purposes
(i.e., so that nix-env users can tell them apart).
*/
setName = name: drv: drv // {inherit name;};
/* Like `setName', but takes the previous name as an argument.
Example:
updateName (oldName: oldName + "-experimental") somePkg
*/
updateName = updater: drv: drv // {name = updater (drv.name);};
/* Append a suffix to the name of a package (before the version
part). */
appendToName = suffix: updateName (name:
let x = builtins.parseDrvName name; in "${x.name}-${suffix}-${x.version}");
/* Apply a function to each derivation and only to derivations in an attrset
*/
mapDerivationAttrset = f: set: lib.mapAttrs (name: pkg: if lib.isDerivation pkg then (f pkg) else pkg) set;
/* Decrease the nix-env priority of the package, i.e., other
versions/variants of the package will be preferred.
*/
lowPrio = drv: addMetaAttrs { priority = 10; } drv;
/* Apply lowPrio to an attrset with derivations
*/
lowPrioSet = set: mapDerivationAttrset lowPrio set;
/* Increase the nix-env priority of the package, i.e., this
version/variant of the package will be preferred.
*/
hiPrio = drv: addMetaAttrs { priority = -10; } drv;
/* Apply hiPrio to an attrset with derivations
*/
hiPrioSet = set: mapDerivationAttrset hiPrio set;
}