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-rw-r--r--libbuild2/config/init.cxx16
1 files changed, 16 insertions, 0 deletions
diff --git a/libbuild2/config/init.cxx b/libbuild2/config/init.cxx
index e92db4c..0472cfd 100644
--- a/libbuild2/config/init.cxx
+++ b/libbuild2/config/init.cxx
@@ -257,6 +257,22 @@ namespace build2
// Note that this variable is not saved in config.build and is expected
// to always be specified as a command line override.
//
+ // We also had the idea of using NULL values as a more natural way to
+ // undefine a configuration variable, which would only work for non-
+ // nullable variables (such as project configuration variables) or for
+ // those where NULL is the default value (most of the others). However,
+ // this cannot work in our model since we cannot reset a NULL override
+ // to a default value. So setting the variable itself to some special
+ // value does not seem to be an option and we have to convey this in
+ // some other way, such as in config.config.disfigure. Another idea is
+ // to invent a parallel set of variables, such as disfig.*, that can be
+ // used for that (though they would still have to be specified with some
+ // dummy value, for example disfig.hello.fancy=). On the other hand,
+ // this desire to disfigure individual variables does not seem to be
+ // very common (we lived without it for years without noticing). So
+ // it's not clear we need to do something like disfig.* which has a
+ // wiff of hack to it.
+ //
auto& c_d (vp.insert<strings> ("config.config.disfigure", true /*ovr*/));
// Hermetic configurations.