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authorEelco Dolstra <e.dolstra@tudelft.nl>2011-08-06T16·05+0000
committerEelco Dolstra <e.dolstra@tudelft.nl>2011-08-06T16·05+0000
commit1ecc97b6bdb27e56d832ca48cdafd3dbb5185a04 (patch)
tree4de27ee42f04bb50766f33a58d830677bd8fa80b /src/libexpr/eval.cc
parent54945a2950174ded83d58336061b4a9990cdbbfd (diff)
* Add a Nix expression search path feature. Paths between angle
  brackets, e.g.

    import <nixpkgs/pkgs/lib>

  are resolved by looking them up relative to the elements listed in
  the search path.  This allows us to get rid of hacks like

    import "${builtins.getEnv "NIXPKGS_ALL"}/pkgs/lib"

  The search path can be specified through the ‘-I’ command-line flag
  and through the colon-separated ‘NIX_PATH’ environment variable,
  e.g.,

    $ nix-build -I /etc/nixos ...

  If a file is not found in the search path, an error message is
  lazily thrown.

Diffstat (limited to 'src/libexpr/eval.cc')
-rw-r--r--src/libexpr/eval.cc6
1 files changed, 6 insertions, 0 deletions
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 5701452f94f1..674fa96f0bc0 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -181,6 +181,12 @@ EvalState::EvalState()
         gcInitialised = true;
     }
 #endif
+
+    /* Initialise the Nix expression search path. */
+    searchPathInsertionPoint = searchPath.end();
+    Strings paths = tokenizeString(getEnv("NIX_PATH", ""), ":");
+    foreach (Strings::iterator, i, paths) addToSearchPath(*i);
+    searchPathInsertionPoint = searchPath.begin();
 }