On 07.05.20 02:13, Daren Scot Wilson wrote:
import std.stdio;
import core.stdc.stdio; // for getchar(). There's nothing similar in D
std libs?
import std.concurrency;
import core.thread; // just for sleep()
Instead of the comment you can write:
import core.thread: sleep;
bool running=true;
char command = '?';
These variables are thread-local by default. That means independent
`running` and `command` variables are created for every thread. If you
make changes in one thread, they won't be visible in another thread.
Use `shared` so that all threads use the same variables:
shared bool running=true;
shared char command = '?';
void cmdwatcher()
{
writeln("Key Watcher");
while (running) {
char c = cast(char)getchar();
if (c>=' ') {
command = c;
writefln(" key %c %04X", c, c);
}
}
}
void main()
{
writeln("Start main");
spawn(&cmdwatcher);
while (running) {
writeln("Repetitive work");
Thread.sleep( dur!("msecs")( 900 ) );
char cmd = command; // local copy can't change during rest of
this loop
For values that don't change, we've got `immutable`:
immutable char cmd = command;
command = ' ';
Note that even when using `shared` you still have to think hard to avoid
race conditions.
This sequence of events is entirely possible:
1) main: cmd = command
2) cmdwatcher: command = c
3) main: command = ' '
It won't happen often, but if it does, your input has no effect.
