d自动提取翻译串

​​原文​​​ 利用​

​D​

​编译时传递格式串给允许用​

​static this()​

​运行时注册格式串的​

​gettext​

​,在​

​version​

​中包装​

​条件​

​,让​

​编译器​

​给你提取串.

// File: lang.d
version(extractStr) {
    int[string] allStrings;
    void main() {
        import std.algorithm;
        import std.stdio;
        auto s = allStrings.keys;
        s.sort();
        writefln("string[string] dict = [\n%(\t%s: \"\",\n%|%)];", s);
    }
}

template gettext(string fmt, Args...)
{
    version(extractStr)
    static this() {
        allStrings[fmt]++;
    }
    string gettext(Args args) {
        import std.format;
        return format(fmt, args);
    }
}

// File: main.d
import mod1, mod2;

version(extractStr) {} else
void main() {
    auto names = [ "Joe", "Schmoe", "Jane", "Doe" ];
    foreach (i; 0 .. names.length) {
        fun1(names[i]);
        fun2(5 + cast(int)i*10);
    }
}

// File: mod1.d
import std.stdio;
import lang;

void fun1(string name) {
    writeln(gettext!"你是%s."(name));
}

// File: mod2.d
import std.stdio;
import lang;

void fun2(int num) {
    writeln(gettext!"多少%d苹果."(num));
}

void fun3() {
    writeln(gettext!"哈哈");
}      

string[string] dict = [
    "你是%s.":"",
    "多少%d苹果.":"",
    "哈哈":"",
];      

class Language { ... }
Language curLang = ...;

version(extractStrings) {
    private int[string] translatableStrings;
    string[] getTranslatableStrings() {
        return translatableStrings.keys;
    }
}

string gettext(string str)() {
    version(extractStrings) {
        static struct StrInjector {
            static this() {
                translatableStrings[str]++;
            }
        }
    }
    return curLang.translate(str);
}

...
auto myFunc() {
    ...
    writeln(gettext!"可译消息");
    ...
}