Feature #15504
Updated by sawa (Tsuyoshi Sawada) over 3 years ago
# Abstract Abstrcat Range is currently now non-frozen. How about freezing to freeze all of Range objects? # Background We froze freeze some types type of objects: objects, Numerics (r47523) and Symbols [Feature #8906]. I believe that making objects immutable solves some kinds kind of programming difficulties. `Range` is mutable mutable, at least when it is written as in Range literal. So we can write the following weird program: ```ruby program. ``` 2.times{ r = (1..3) p r.instance_variable_get(:@foo) #=> 1st time: nil #=> 2nd time: :bar r.instance_variable_set(:@foo, :bar) } ``` In in `range.c`, there is a comment (thanks znz-san): ```c ``` static void range_modify(VALUE range) { rb_check_frozen(range); /* Ranges are immutable, so that they should be initialized only once. */ if (RANGE_EXCL(range) != Qnil) { rb_name_err_raise("`initialize' called twice", range, ID2SYM(idInitialize)); } } ``` # Patch ``` Index: range.c =================================================================== --- range.c (リビジョン 66699) +++ range.c (作業コピー) @@ -45,6 +45,8 @@ RANGE_SET_EXCL(range, exclude_end); RANGE_SET_BEG(range, beg); RANGE_SET_END(range, end); + + rb_obj_freeze(range); } VALUE ``` # Discussion There are several usages usage of mutable Range in the tests. * (1) Taint-flag taint-flag * (2) Add add singleton methods. * (3) Subclass subclass with mutable states Maybe (2) and (3) are crucial. points. Thanks, Koichi