- Everyone should avoid global static initialization of complex data, even though it's the most convenient way to achieve certain effects. The chances of screwing up something with the initialization order of variables are just too high, and impossible to control. - There are people who like C++ template metaprogramming. Some very cool things can be achieved with it. But all C++ projects that I've seen ban it. Some because they want new people to be able to easily pick up the project. Others just because of the tool issues around heavy duty template use, like slow compilation speed and horrible error messages. - C++ has many different kinds of inheritance. In practice many projects will ban most of them, and only allow single public inheritance of bases classes with implementation, and single or multiple public inheritance of base classes with only virtual methods. The convenience of multiple implementation inheritance is just not viewed as sufficient to balance the risk of shooting yourself in the foot. And the utility of non-public inheritance is not viewed as high enough to balance needing to explain it to people coming from Java.
Or how about Perl?
- Anybody suggesting changing $[, the variable that controls the array indexing base, would generally be given a good thrashing. Allowing changing the language (at runtime!) from 0-based indexing to 1-based was presumably thought to be a benign feature at some point, but it's hard to see how in retrospect. - As a more modern example, later Perl got the ability to embed executable Perl code inside regular expressions with (??{}). Again, it's totally possible to see uses for this. But in practice it's so inscrutable (and at least in the past so crashy), that it's best reserved for stunt coding. Maybe not using it means rewriting some extremely compact regular expression in a way that's 3x longer, but that's still a net win.
Does that help showing the flavor of things you'd want to avoid?
