Re: Create an empty json object with std.json
On Friday, 22 January 2016 at 11:53:11 UTC, Andrea Fontana wrote:
If you declare a JSONValue like this:
JSONValue json;
then:
assert(json.type() == JSON_TYPE.NULL);
Documentation at
https://dlang.org/phobos/std_json.html#.JSONValue.type.2
suggests not to change type but to assign a new value instead.
My problem is: how can I assign an empty object like {}?
The only way i found is using that deprecated method:
json.type = JSON_TYPE.OBJECT;
or
json = `{}`.parseJSON;
Please notice that to init as array this works:
json = JSONValue[].init;
What you can do is use the JSONValue ctor and pass it an empty
associative array
auto json = JSONValue(string[string].init); //or
JSONValue((JSONValue[string]).init)
It's a little verbose but gets the job done without using
deprecated things or parseJSON
Re: core.time Duration how to get units in double/float format?
On Tuesday, 19 January 2016 at 15:25:58 UTC, wobbles wrote: On Tuesday, 19 January 2016 at 14:07:50 UTC, Borislav Kosharov wrote: On Monday, 18 January 2016 at 12:46:31 UTC, Jonathan M Davis wrote: [...] I want to use float time in a game where I call the update method passing the delta time as float seconds. It's more easy to multiply the dt with a speed constant meaning how much the object will move after 1 second. Such float delta time is used in many game engines and it's somewhat standart way of doing it. Also the method you wrote returns a string and I need a float to multiply it with a number. Thanks for the reply anyway Checkout out how DSFML handles this. You simply pass around a Clock object that you can restart every frame using clock.restart(); You then call your update function with update(Clock.getElapsedTime()); Then in each objects update(Time t) method you just get the time in whatever unit you want. Works pretty well. http://www.dsfml.com/ Yes that's exactly what I'm using. But they changed it to return a Duration instead of Time and that broke my code. See the source https://github.com/Jebbs/DSFML/blob/master/src/dsfml/system/clock.d#L65
Re: core.time Duration how to get units in double/float format?
On Monday, 18 January 2016 at 12:46:31 UTC, Jonathan M Davis
wrote:
In general, using floating point values with time is an
incredibly bad idea. It can certainly make sense when printing
stuff out, but using it in calculations is just asking for
trouble given all of the unnecessary imprecision that it adds.
So, Duration does not directly support floating point values at
all, and that's very much on purpose. I'd strongly argue that
the fact that TickDuration does was a mistake.
So, if you're doing floating point calculations with time, I'd
strongly urge you to rethink your code. And if you're just
trying to print out the a duration as a floating point value,
because it's nice to view that way, then that's fine, but
you'll need to do the conversion yourself. And it's not that
hard. It just isn't handed to you directly, because aside from
printing, code really shouldn't be using floating point values
for time. e.g.
string toFloatingSeconds(Duration d)
{
import std.conv;
enum hnsecsPerSecond = convert!("seconds", "hnsecs")(1);
auto s = d.split!("seconds", "hnsecs")();
return to!string(s.seconds + cast(real)(s.hnsecs) /
hnsecsPerSecond);
}
And yes, that's a bit more of a pain than using to!("seconds",
float) with TickDuration, but it's also the sort of thing that
most code really shouldn't be doing. So, adding that
functionality to Duration would just encourage folks to write
buggy code.
- Jonathan M Davis
I want to use float time in a game where I call the update method
passing the delta time as float seconds. It's more easy to
multiply the dt with a speed constant meaning how much the object
will move after 1 second. Such float delta time is used in many
game engines and it's somewhat standart way of doing it. Also the
method you wrote returns a string and I need a float to multiply
it with a number.
Thanks for the reply anyway
Re: core.time Duration how to get units in double/float format?
On Sunday, 17 January 2016 at 18:57:13 UTC, biozic wrote:
On Sunday, 17 January 2016 at 14:43:26 UTC, Borislav Kosharov
wrote:
Seeing that TickDuration is being deprecated and that I should
use Duration instead, I faced a problem. I need to get total
seconds like a float. Using .total!"seconds" returns a long
and if the duration is less than 1 second I get 0. My question
is whats the right way to do it. Because I saw that
TickDuration has a to!("seconds", float) method, but Duration
doesn't have one. I can convert Duration to TickDuration and
call to but seeing that its deprecated makes me think there is
a better way.
Why not just use a smaller granularity for Duration.total and
convert the result?
duration.total!"nsecs" / cast(float) 1e9
Yea I could do that, but its not intuitive to get a total of one
magnitude to just convert it to another. My question is why
doesn't `to!` accept Duration.
core.time Duration how to get units in double/float format?
Seeing that TickDuration is being deprecated and that I should
use Duration instead, I faced a problem. I need to get total
seconds like a float. Using .total!"seconds" returns a long and
if the duration is less than 1 second I get 0. My question is
whats the right way to do it. Because I saw that TickDuration has
a to!("seconds", float) method, but Duration doesn't have one. I
can convert Duration to TickDuration and call to but seeing that
its deprecated makes me think there is a better way.
How to split a string/array with multiple separators?
I want to split a string using multiple separators. In std.array the split function has a version where it takes a range as a separator, but it works differently than what I want. Say if I call it with " -> " it will search for the whole thing together. I want to pass split a list of separators say [":", ",", ";"] and if it finds any of those to split it. Sorry if this questions is stupid but I cant find how to do it.
Re: How to check if JSONValue of type object has a key?
Thanks guys that was I was looking for!
How to check if JSONValue of type object has a key?
I'm using std.json for parsing json. I need to check if a
specific string key is in JSONValue.object. The first thing I
tried was:
JSONValue root = parseJSON(text);
if(root["key"].isNull == false) {
//do stuff with root["key"]
}
But that code doesn't work, because calling root["key"] will
throw an exception of key not fount if "key" isn't there.
I need some method `root.contains("key")` method to check if the
object has a key.
Thanks in advance!
