On Saturday, 21 April 2012 at 01:31:45 UTC, Jonathan M Davis
wrote:
Okay. I should have said that Java and C# require that a
variable be written
to before being used. Regardless, they take the approach of
requiring that a
variable be initialized/assigned a value rather than letting it
be garbage
(like C/C++) or initializing it to a default value (like D).
It solves only part of the problem. If a simple, unconditional
default-initialization was an objectively superior solution,
nobody would bother implementing control flow graphs.
When "int x;" and "int x = 0;" are semantically identical, the
intention of the programmer isn't clear in the case of "int x;"
(talking about local variables only, of course). Is the default
value relied upon intentionally in the program? What if it
unintentionally reads the default value? The default value is
more helpful than garbage when debugging (especially for
non-integer types), but with a proper implementation, errors like
these can be caught at compile-time.
You could introduce coding conventions in your project to manage
the issue, but then we're in faith-based programming territory.
The control flow graph takes care of correctly determining
whether a variable has been initialized.
And Walter seems to hate flow analysis like the plague (due to
its increased
complexity IIRC).
It's well-trodden area, it doesn't have to be difficult.
_Very_ little in D requires or does flow
analysis.
And D is worse off because of it.
