Jsonize species footsteps sound

[ZhilkinSerg]

Summary

SUMMARY: Features "Jsonize species footsteps sound"

Purpose of change

Allow definition of monster species footsteps sound via json.

[anothersimulacrum]

Typo? (footstepz instead of footsteps)

[BevapDin]

Translation should occur in get_footsteps. Changing the language midway through a game will not change the stored (and already translated) string, so the footsteps will still be in the language that was selected upon loading the game.

[ZhilkinSerg]

That is intentional - translation calls inside of footsteps function are very expensive.

[kevingranade]

It's possible to detect language changes and swap out this value, we can look into doing that in a future PR.

[ZhilkinSerg]

I was thinking whether it is possible not to make rather costly translation calls in a runtime, but instead do translation on json data loading (possibly with data/translation reloading when language is changed or simply requiring game restart on language change).

I don't think that changing language during running game is a frequent use-case. It is really cheaper to select language and reload game then doing thousands of calls to get the same footstep string.

[BrettDong]

I don't think translation calls are expensive. After a simple benchmark, 10 samples without I18N and another 10 samples with I18N, it seems a single gettext call only costs extra 0.32us on a pretty old Core Duo laptop.

#include <iostream>
#include <libintl.h>
using namespace std;
const int cnt = 1000*1000;
int main()
{
    setlocale(LC_ALL, "zh_CN");
    bindtextdomain( "cataclysm-dda", "lang/mo" );
    bind_textdomain_codeset( "cataclysm-dda", "UTF-8" );
    textdomain( "cataclysm-dda" );
    for(int i = 0; i < cnt; i++)
#ifdef I18N
        cout << gettext("battery") << endl;
#else
        cout << "battery" << endl;
#endif
    return 0;
}

[ZhilkinSerg]

We are doing various optimizations now and libgettext calls started to appear on top in various scenarios after other things were optimized.

[BevapDin]

Translatable strings in JSON require separate code in "lang/extract_json_strings.py" to extract them for translation.

[ZhilkinSerg]

I've updated Python script - hope everything was correct.

CC: @BrettDong