forked from lix-project/lix
5cd72598fe
Impure derivations are derivations that can produce a different result
every time they're built. Example:
stdenv.mkDerivation {
name = "impure";
__impure = true; # marks this derivation as impure
outputHashAlgo = "sha256";
outputHashMode = "recursive";
buildCommand = "date > $out";
};
Some important characteristics:
* This requires the 'impure-derivations' experimental feature.
* Impure derivations are not "cached". Thus, running "nix-build" on
the example above multiple times will cause a rebuild every time.
* They are implemented similar to CA derivations, i.e. the output is
moved to a content-addressed path in the store. The difference is
that we don't register a realisation in the Nix database.
* Pure derivations are not allowed to depend on impure derivations. In
the future fixed-output derivations will be allowed to depend on
impure derivations, thus forming an "impurity barrier" in the
dependency graph.
* When sandboxing is enabled, impure derivations can access the
network in the same way as fixed-output derivations. In relaxed
sandboxing mode, they can access the local filesystem.
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| .. | ||
| derivation-goal.cc | ||
| derivation-goal.hh | ||
| drv-output-substitution-goal.cc | ||
| drv-output-substitution-goal.hh | ||
| entry-points.cc | ||
| goal.cc | ||
| goal.hh | ||
| hook-instance.cc | ||
| hook-instance.hh | ||
| local-derivation-goal.cc | ||
| local-derivation-goal.hh | ||
| substitution-goal.cc | ||
| substitution-goal.hh | ||
| worker.cc | ||
| worker.hh | ||