[phobos] enforce() vs. assert() for range primitives

[David Simcha]

A valid criticism in general.  However, all of the ranges in question 
are templates, so each instantiation is compiled in whatever mode your 
program is compiled in.

On 8/18/2010 7:08 PM, Jonathan M Davis wrote:
> The ideal situation would be to use asserts in all cases where it's going to be
> bugs in the program rather than bad user input and that they go away in release
> mode. The problem is the fact that Phobos is compiled as an external library
> rather than being compiled in with your code when you compile. And since there's
> no way (at least no standard way) to have a release and debug version of the
> Phobos libraries, with the release version being used in release mode and the
> debug version being used in debug mode, that pretty much means that you _always_
> compile your code with the release version of Phobos. This makes assert
> _useless_ for users of the library. If you want checks beyond within Phobos
> code, you _have_ to use enforce(), and since enforce has issues with inlining
> and it doesn't go away in release mode, it's like forcing a portion of Phobos
> into debug mode.
>
> _Ideally_, we would find some sort of standard way to make Phobos used in debug
> mode when compiling in debug mode and release mode when compiling in release
> mode. That way, asserts could be used in a lot of these cases since a lot of
> them really shouldn't be checked in release mode. Personally, I _really_ don't
> like the fact that the libraries aren't necessarily in the same mode as your
> code, though I'm not sure that there's a good way to deal with that other than
> having some standard naming scheme for debug vs release libraries which Phobos
> uses and dmd understands so that you get a debug version when compiling your
> code in debug mode, and you get a release version when compiling in release
> mode. Barring that however...
>
> You'd almost have to take it on a case by case basis. In some cases, you're
> going to need checks and it would be bad not to have them, while in others, it
> would just cost too much to leave them in. It's a tough call. If anything
> though, I think that it's a prime example of needing to find a better way to deal
> with debug vs release and libraries. If we had a standard way to have both
> available, then dmd could use both with user code, and then we can use asserts
> like they should be used. As it stands though, we're probably going to have to
> use enforce() where we _need_ checks for safety and asserts otherwise. But since
> using asserts is almost pointless.... Bleh. It's just ugly.
>
> - Jonathan M Davis
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