wroclaw-git-backups/nix
1
0
Fork 0
mirror of https://github.com/NixOS/nix synced 2025-06-26 11:41:15 +02:00
Code Activity

* Allow a default value in attribute selection by writing

Browse source 
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
Download patch file Download diff file Expand all files Collapse all files

19
src/libexpr/eval.cc
View file

@ -632,7 +632,6 @@ void ExprVar::eval(EvalState & state, Env & env, Value & v)
unsigned long nrLookups = 0;
unsigned long nrLookupSize = 0;
void ExprSelect::eval(EvalState & state, Env & env, Value & v)
{
@ -646,11 +645,20 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
foreach (AttrPath::const_iterator, i, attrPath) {
nrLookups++;
state.forceAttrs(*vAttrs);
nrLookupSize += vAttrs->attrs->size();
Bindings::iterator j;
if ((j = vAttrs->attrs->find(*i)) == vAttrs->attrs->end())
throwEvalError("attribute `%1%' missing", showAttrPath(attrPath));
if (def) {
state.forceValue(*vAttrs);
if (vAttrs->type != tAttrs ||
(j = vAttrs->attrs->find(*i)) == vAttrs->attrs->end())
{
state.eval(env, def, v);
return;
}
} else {
state.forceAttrs(*vAttrs);
if ((j = vAttrs->attrs->find(*i)) == vAttrs->attrs->end())
throwEvalError("attribute `%1%' missing", showAttrPath(attrPath));
}
vAttrs = j->value;
pos = j->pos;
}
@ -1270,7 +1278,6 @@ void EvalState::printStats()
printMsg(v, format(" number of thunks: %1%") % nrThunks);
printMsg(v, format(" number of thunks avoided: %1%") % nrAvoided);
printMsg(v, format(" number of attr lookups: %1%") % nrLookups);
printMsg(v, format(" attr lookup size: %1%") % nrLookupSize);
}