On Thu, Feb 11, 2021 at 12:12:36PM -0800, Walter Bright via
Digitalmars-d-announce wrote:
[...]
> https://p0nce.github.io/d-idioms/
Not bad, but it seems to be missing some of the newer idioms.
Like the templated static this trick for transparently encoding
compile-time information at runtime. For example:
import std.regex;
void main(string[] args) {
foreach (arg; args) {
if (arg.match(Re!`some.*regex(pattern)+`)) {
... // do something
}
}
}
template Re(string reStr) {
Regex!char re;
static struct Impl {
static this() {
re = regex(reStr);
}
}
string Re() { return re; }
}
The Re template captures the regex string at compile-time and injects it
into Impl's static this(), which compiles the regex at program startup
at runtime, then the eponymous function Re() simply returns the
precompiled value.
The result:
- Regexes are automatically picked up at compile-time;
- But expensive compile-time generation of the regex (which consumes
lots of compiler memory and slows down compilation) is skipped;
- Compilation of the regex happens only once upon program startup and
cached, and thereafter is a simple global variable lookup.
- Multiple occurrences of the Re template with the same regex is
automatically merged (because it's the same instantiation of the
template).
D features used:
- compile-time string parameters
- static this()
- eponymous templates
- reuse of template instantiations that have the same arguments
[...]
> https://www.reddit.com/r/programming/comments/lhssjp/idioms_for_the_d_programming_language/
There doesn't appear to be any discussion happening here.
T
--
If it breaks, you get to keep both pieces. -- Software disclaimer notice
