Re: Epoch time + msecs
On Friday, 13 November 2015 at 23:12:34 UTC, Steven Schveighoffer wrote: If you cannot update to the latest compiler Didn't realised this feature is so new to the compiler. In my case, it is no problem to update the compiler, and I will. Thanks! On Saturday, 14 November 2015 at 03:10:17 UTC, Jonathan M Davis wrote: auto seed = Clock.currTime().stdTime; (...) and you don't have to do any math. Perfect. On Saturday, 14 November 2015 at 03:10:17 UTC, Jonathan M Davis wrote: Alternatively, std.random.unpredictable seed is there specifically to provide an unpredictable seed. It's probably best to just use that if you don't have a good reason not to. Of course. That's why I mentioned my purpose of using Clock.currTime(), in the hope I got corrected in using the right and offical seed method which I failed to find, which brings me to another point. The D docs seem very thorough and complete to me but less accessible in comparison to, e.g., Perl docs, Php docs, or Ruby docs. In particular I have difficulties in understanding the headers of the standard library function specifications (e.g.,: auto uniform(string boundaries = "[)", T1, T2, UniformRandomNumberGenerator)(T1 a, T2 b, ref UniformRandomNumberGenerator urng) if (isFloatingPoint!(CommonType!(T1, T2)) && isUniformRNG!UniformRandomNumberGenerator);) These headers are necessary and give loads of information. D is no toy language, that's for sure. Maybe a tutorial should be written on how to read such headers and how to read the standard library docs in general. I am making notes for myself, but these are of too little quality to be used in the public domain. Like I said: I am spoiled by scripting languages. Thanks again, your answers have helped me a lot.
Epoch time + msecs
How to get current time as a float (or a double or a real) as a Unix epoch + milliseconds (e.g, 1447437383.465, or even 1447437383.46512 with finer resolution)? I read http://dlang.org/intro-to-datetime.html and the docs of course. I came this far auto ct = Clock.currTime(); auto milliseconds = ct.fracSec.msecs; auto epoch = ct.toUnixTime(); But I think this is not the shortest way and I don't know how to combine and cast into a float (or a double or a real). My goal was to multiply by 1000 and feed as this number as a seed to D's random number generator. But there may be beter ways to make a seed.
Re: Epoch time + msecs
On Friday, 13 November 2015 at 18:27:42 UTC, Steven Schveighoffer
wrote:
On 11/13/15 1:00 PM, Handyman wrote:
What I would do is this:
auto t = (Clock.currTime() -
SysTime.fromUnixTime(0)).total!"msecs" / 1000.0
Thanks, Steve.
import std.stdio;
import std.datetime;
void main() {
auto t = (Clock.currTime() -
SysTime.fromUnixTime(0)).total!"msecs" / 1000.0;
writeln(t);
}
Gives an error: Error: no property 'fromUnixTime' for type
'SysTime'.
When I do
auto t = (Clock.currTime() -
unixTimeToStdTime(0)).total!"msecs" / 1000.0;
I get
Error: incompatible types for ((currTime(opCall())) -
(unixTimeToStdTime(0))): 'SysTime' and 'long'
and when I do
auto t = (Clock.currTime() -
SysTime.fromUnixTime(0)).total!"msecs" / 1000.0;
I get:
Error: no property 'fromUnixTime' for type 'SysTime'
I think I am spoiled by 'typeless' scriping languages.
Re: parallel
On Thursday, 5 November 2015 at 20:40:00 UTC, anonymous wrote: So one of your four cores has to make two dishes. That takes two seconds. So make fine-grained? foreach (i; 0..50) Thread.sleep(20.msecs); But then my program still says: '2 secs'. Please enlighten me.
Re: parallel
On Thursday, 5 November 2015 at 20:45:25 UTC, Ali Çehreli wrote: That's still 1 second per task. The function prepare() cannot be executed by more than one core. Thanks. OK. So 'prepare' is atomic? Then let's turn it around: how can I make the cores prepare a meal of 5 dishes in 1.25 secs? Should I rewrite, or split, 'prepare'?
Re: parallel
On Thursday, 5 November 2015 at 20:54:37 UTC, anonymous wrote: There is not attempt to split the `prepare` action up and run parts of it in parallel. So 1.25 secs is impossible?
Re: parallel
On Thursday, 5 November 2015 at 21:10:16 UTC, anonymous wrote: parallel(iota(50))) Wow. I have dealt with ranges and 'iota' (and with parallel), but I admit I have to think hard about this example. Thanks a bunch all for your patience.
parallel
import std.stdio;
import core.thread;
import std.datetime; // for stopwatch
import std.parallelism;
void say(string s) { // write and flush
writeln(s);
stdout.flush();
}
struct Dish {
string name;
void prepare() {
say("Start with the " ~ name ~ ".");
Thread.sleep(1.seconds); // kunstmatig tijd verbruiken
say("Finished the " ~ name ~ ".");
}
}
void main() {
auto dishes = [ Dish("soup"), Dish("sauce"), Dish("fries"),
Dish("fish"), Dish("ice") ];
auto sw = StopWatch(AutoStart.yes);
foreach (dish; parallel(dishes, 1)) dish.prepare();
sw.stop;
writefln("Diner is ready. Cooking took %.3f seconds.",
cast(float) sw.peek.msecs / 1000);
}
gives:
Start with the soup.
Start with the sauce.
Start with the fries.
Start with the fish.
Finished the sauce.
Finished the fries.
Start with the ice.
Finished the soup.
Finished the fish.
Finished the ice.
Diner is ready. Cooking took 1.999 seconds.
Seems that 4 cores go all out on first 4 dishes, then 1 core
deals with the last dish. With 4 cores I expect diner is ready
after 5/4 = 1.25 secs though. What did I do wrong?
Enough introspection to report variable name of calling argument
Is the following possible in D? To call a (unary) function f with variable a, and let f print: Called with argument named 'a'. I am of course asking for a generic solution, independent of the actual variable name (in this case, 'a'). I am aware that I am likely asking the impossible because of how the function call mechanism is implemented in most programming languages, hence in D. Still, it might be possible given D's stong introspection capabilities / traits / pragma's / whathaveyou's.
