开发者

How do I generate an array in D?

开发者 https://www.devze.com 2023-04-03 23:44 出处:网络
I have this c++11 code: auto gen = []() -> double { /* do stuff */ }; std::generate(myArray.begin(), myArray.end(), gen);

I have this c++11 code:

auto gen = []() -> double { /* do stuff */ };
std::generate(myArray.begin(), myArray.end(), gen);

How would I do the same with D's array? std.algorithm.fill doesn't take a function object, and I don't know how to pass a function to 开发者_高级运维recurrence.


Here's a version that seems to work:

import std.algorithm, std.array, std.range, std.stdio;

void main() {
  writefln("%s", __VERSION__);
  int i;
  auto dg = delegate float(int) { return i++; };
  float[] res = array(map!dg(iota(0, 10)));
  float[] res2 = new float[10];
  fill(res2, map!dg(iota(0, res2.length)));
  writefln("meep");
  writefln("%s", res);
  writefln("%s", res2);
}

[edit] Added fill-based version (res2).

I tested it in Ideone (http://www.ideone.com/DFK5A) but it crashes .. a friend with a current version of DMD says it works though, so I assume Ideone's DMD is just outdated by about ten to twenty versions.


You could do something like

auto arr = {/* generate an array and return that array */}();

If it's assigned to a global it should be evaluated at compile-time.

You can also use string mixins to generate code for an array literal.

0

精彩评论

暂无评论...
验证码 换一张
取 消

关注公众号