diff options
Diffstat (limited to 'libbuild2/variable.hxx')
| -rw-r--r-- | libbuild2/variable.hxx | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/libbuild2/variable.hxx b/libbuild2/variable.hxx index d00243e..9c1e02c 100644 --- a/libbuild2/variable.hxx +++ b/libbuild2/variable.hxx @@ -276,7 +276,13 @@ namespace build2 // Extra data that is associated with the value that can be used to store // flags, etc. It is initialized to 0 and copied (but not assigned) from // one value to another but is otherwise untouched (not even when the - // value is reset to NULL). + // value is reset to NULL) unless it is part of variable_map::value_data, + // in which case it is reset to 0 on each modification (version + // increment; however, see reset_extra flag in variable_map::insert()). + // + // (The reset on each modification semantics is used to implement the + // default value distinction as currently done in the config module but + // later probably will be done for ?= and $origin()). // // Note: if deciding to use for something make sure it is not overlapping // with an existing usage. @@ -1506,7 +1512,10 @@ namespace build2 using value::value; using value::operator=; - size_t version = 0; // Incremented on each modification (variable_cache). + // Incremented on each modification, at which point we also reset + // value::extra to 0. + // + size_t version = 0; }; // Note that we guarantee ascending iteration order (e.g., for predictable @@ -1606,6 +1615,7 @@ namespace build2 { assert (l.vars == this); value& r (const_cast<value&> (*l.value)); + r.extra = 0; static_cast<value_data&> (r).version++; return r; } @@ -1629,10 +1639,11 @@ namespace build2 // As above but also return an indication of whether the new value (which // will be NULL) was actually inserted. Similar to find(), if typed is - // false, leave the value untyped even if the variable is. + // false, leave the value untyped even if the variable is. If reset_extra + // is false, then don't reset the existing value's value::extra. // pair<value&, bool> - insert (const variable&, bool typed = true); + insert (const variable&, bool typed = true, bool reset_extra = true); // Note: does not deal with aliases. // |