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* Allow a default value in attribute selection by writing

x.y.z or default

  (as originally proposed in
  https://mail.cs.uu.nl/pipermail/nix-dev/2009-September/002989.html).

  For instance, an expression like

    stdenv.lib.attrByPath ["features" "ckSched"] false args

  can now be written as

    args.features.ckSched or false
This commit is contained in:
Eelco Dolstra 2011-07-13 12:19:57 +00:00
parent 2b9e29b1c8
commit 0a623a10c7
9 changed files with 70 additions and 22 deletions

View file

@ -44,6 +44,7 @@ void ExprVar::show(std::ostream & str)
void ExprSelect::show(std::ostream & str)
{
str << "(" << *e << ")." << showAttrPath(attrPath);
if (def) str << " or " << *def;
}
void ExprOpHasAttr::show(std::ostream & str)
@ -211,6 +212,7 @@ void ExprVar::bindVars(const StaticEnv & env)
void ExprSelect::bindVars(const StaticEnv & env)
{
e->bindVars(env);
if (def) def->bindVars(env);
}
void ExprOpHasAttr::bindVars(const StaticEnv & env)