Hello,
Sorry if this question is a bit naive or shows a misunderstanding
of RVO.
I was trying to see if my C compiler was doing RVO with struct,
but after testing it at is apparently not the case.
Since I have heard that D supports RVO I wanted to give it a try
in D. But apparently it
Oops found it my self.
I had to use
auto x = foo();
I tried your code as this and it doesn't work.
#!/usr/bin/rdmd -O
import std.stdio;
struct S {
int a;
@disable this(this);
};
S foo() {
S v;
v.a = 1;
writeln();
return v;
}
void main()
{
S x;
x = foo();
writeln();
}
I even tried with dmd -O without
On Friday, 3 June 2016 at 15:23:16 UTC, Jonathan M Davis wrote:
Thank you for your detailed explanation.
If I have a static immutable object, I don't have to declare it
as shared because it is implicit. Right ?
Changing my __gshared into static shared raises some errors which
I don't know
final Tuple!(int,"value",bool,"hasValue") value(const
string name) { return nameImpl(value); }
Sorry, this is the error. It should have been
final Tuple!(int,"value",bool,"hasValue") value(const
string name) { return valueImpl(name); }
I have an immutable final class with methods with the following
signature
import std.typecons;
immutable class Base{
...
@safe pure nothrow
final Tuple!(int,"value",bool,"hasValue") value(const string
name) { return nameImpl(value); }
@safe pure nothrow
protected
In a first implementation I defined a named enum in my class
which I could use with my template function foo.
final class Info {
...
enum Value { info_1 = 1, ... }
...
static bar(Value e) {...}
}
void foo(T)(T.Value e) { T.bar(e); }
I could then write :
This is awesome! I added it to my D cookbook.
Thank you very much.
On Monday, 6 June 2016 at 15:28:35 UTC, John wrote:
Thank you John and Adam. That was a quick answer !
Hello
I'm writing some code that I want to be portable across Posix and
Windows.
What is the recommended code convention for such type of code ?
80% of the class implementation is the same for both OS.
Should I write the following and copy past the 80%
version( Windows ) {
import
On Monday, 13 June 2016 at 00:57:11 UTC, Alex Parrill wrote:
This is misleading. Any sort of cooperative system needs
synchronization when two or more tasks try to access the same
data, whether those "tasks" are OS threads, fibers, different
machines on a network, etc.
That is true. Sorry.
When trying to compile the following code I get a compilation
error
import std.stdio;
class Info
{
final string name() { return nameImpl(); }
protected abstract string nameImpl();
}
final class MyInfo : Info
{
this() { assert(__ctfe); }
private __gshared info_ = new
On Friday, 3 June 2016 at 21:04:41 UTC, ag0aep6g wrote:
Thank you ag0aep6g, especially for the missing shared in my
static this !
Since I'm implementing a (hopefully useful) library, it would be
unpleasant for users to have to cast away shared to print the
info.
It works with immutable at
I couldn't find any information about this on the dlang web site.
What is the effect adding the immutable attribute to a class like
this
immutable class MyClass { ... }
The compiler doesn't complain.
Will it add the immutable attribute to all members ?
On Friday, 27 May 2016 at 21:41:02 UTC, Kagamin wrote:
On Friday, 27 May 2016 at 20:20:36 UTC, chmike wrote:
Is this code valid D or is the behavior undefined due to the
cast ?
A mutable object can be synchronized on:
synchronized(Category.instance){}
This will create and store a mutex in the
On Saturday, 28 May 2016 at 08:47:48 UTC, Kagamin wrote:
For a trick of static mutable allocation see
https://github.com/dlang/druntime/pull/1325
Thank you that looks promising. I'll study an experiment with the
code.
If I would like that the instances are not in TLS, can I use the
following
On Sunday, 12 June 2016 at 05:11:57 UTC, Ali Çehreli wrote:
For convenience, here's the link:
http://www.ustream.tv/recorded/86352137/highlight/699197
unfortunately iPads are not supported to view the video. :(
I see two major benefits of fibers overs threads.
Fibers don't need
On Friday, 3 June 2016 at 12:41:39 UTC, Jonathan M Davis wrote:
...
On a side note, be warned that you almost certainly shouldn't
be using __gshared like this. It's intended for interacting
with C code not for D objects to be marked with D. As far as
the type system is concerned, __gshared
On Saturday, 28 May 2016 at 08:47:48 UTC, Kagamin wrote:
For a trick of static mutable allocation see
https://github.com/dlang/druntime/pull/1325
In the following instruction of the above commit, what effect has
the [] after init ?
_store[0 .. __traits(classInstanceSize, T)] =
On Friday, 27 May 2016 at 20:20:36 UTC, chmike wrote:
I need to create an app wide singleton instance for my class.
The singleton is immutable, but I want to allow mutable
references to that singleton object so that I can do fast 'is'
tests.
I declared this
class Category
{
protected
In my long quest to implement a flyweight pattern with objects
instantiated at compile time, I was indirectly notified of the
possible problem of synchronization.
In a flyweight pattern the user has the impression there are
distinct instances where in fact objects with the same state
(member
Oops, the duplicate alias instruction and main are copy past
error. It looks like the code was already too complex for me. ;)
Here is the code I tested
import std.typecons;
Rebindable!(immutable TestImpl) Test;
class TestImpl
{
void foo() {}
Test test() { __gshared x = new
Hello,
here is a program stripped down to the minimum code that doesn't
compile
import std.typecons;
Rebindable!(immutable TestImpl) Test;
Rebindable!(immutable TestImpl) Test;
class TestImpl
{
void foo() {}
Test test() { __gshared x = new immutable TestImpl; return
On Saturday, 28 May 2016 at 21:21:34 UTC, ag0aep6g wrote:
On 05/28/2016 09:54 PM, chmike wrote:
The only inconvenience left is that we can't have mutable
references
to immutable objects.
There is std.typecons.Rebindable for that.
That would be a good news. What is the right way to use it ?
This code compile, but array appending doesn't work
alias Rebindable!(immutable(InfoImpl)) Info;
class InfoImpl
{
void foo() {}
static immutable(InfoImpl) info()
{
__gshared immutable InfoImpl x = new immutable InfoImpl;
return x;
}
}
void main()
{
On Sunday, 29 May 2016 at 06:49:42 UTC, chmike wrote:
What is the right way to use it ?
I answer to my self after testing so that people looking for that
info can find it here.
The right way would be
immutable Category category_;
Rebindable!(immutable Category) instance() { return
On Monday, 30 May 2016 at 21:32:46 UTC, Alex Parrill wrote:
On Monday, 30 May 2016 at 10:09:19 UTC, chmike wrote:
Why can't info() return a Rebindable!(immutable(InfoImpl)) ?
What do you mean? `info` returns an `immutable(InfoImpl)`, not
a `Rebindable!(immutable(InfoImpl))`. Rebindable
I need to create an app wide singleton instance for my class.
The singleton is immutable, but I want to allow mutable
references to that singleton object so that I can do fast 'is'
tests.
I declared this
class Category
{
protected static immutable Category instance_ = new Category;
On Tuesday, 31 May 2016 at 06:40:31 UTC, Era Scarecrow wrote:
On Tuesday, 31 May 2016 at 05:31:59 UTC, chmike wrote:
My conclusion is that rebindable is not a satisfying solution
to have mutable references to immutable objects.
I don't understand the rationale of these immutable
references.
On Sunday, 29 May 2016 at 20:40:52 UTC, qznc wrote:
On Sunday, 29 May 2016 at 18:15:16 UTC, qznc wrote:
On Sunday, 29 May 2016 at 17:38:17 UTC, Jonathan M Davis wrote:
And if you're not simply comparing for equality, what are you
looking to figure out? Without more information about what
On average there would be less than 4 bytes remaining to compare.
So a simple straightforward byte comparison should do the job
efficiently.
Sorry for the confusing subject, I couldn't find a concise
formulation of my question.
I have a set of classes derived from the same interface so that I
can use polymorphism.
I would like to store the name of the class as a string so that
it can be retrieved as a static member of the class
I'm implementing the flyweight pattern. It means that I have a
set of object instances representing all the possible values.
This allows me to manipulate "values" by simply manipulating
references to the instance. Testing "value" equality boils down
to simply compare reference value. I hope
Unfortunately it is not possible to write this
import std.typecons;
class Info{...}
rebindable!Info x;
I get the following error message
source/app.d(11,3): Error: template std.typecons.rebindable
matches more than one template declaration:
/usr/include/dmd/phobos/std/typecons.d(1675,14):
Since I'm trying to implement a flyweight pattern, the opEqual
need only comparision of reference in my case.
By the way, what operation is the switch performing ? OpEqual or
is ?
Hello,
I'm planning to call some posix functions core.sys.posix that may
set the errno value in case of error. e.g. read() or write().
Checking the std.exception documentation I see that
ErrnoException may be thrown when errors setting errno may occur.
Does this affect the posix calls ?
On Thursday, 19 May 2016 at 15:33:21 UTC, ag0aep6g wrote:
. . .
interface AThing
{
final string name() { return nameImpl(); }
string nameImpl();
}
class OneThing : AThing
{
static string name() { return "OneThing"; }
override string nameImpl() { return name(); }
}
class
There is a benefit in not allowing to get pointers to class
members. It allows to have movable object instances and this give
access to some faster GC algorithms like generational garbage
collection which is in use in Java.
As an old C++ programmer and newbee in D programming, the D
On Saturday, 21 May 2016 at 08:24:19 UTC, Ali Çehreli wrote:
On 05/21/2016 01:07 AM, chmike wrote:
> Unfortunately it is not possible to write this
>
> import std.typecons;
> class Info{...}
> rebindable!Info x;
You have a capitalization typo. Rebindable is a type template,
rebindable is a
This thread is a followup of
https://forum.dlang.org/post/vuljzyufphsywzevu...@forum.dlang.org
with a refocused subject and question.
I'm looking for a mutable reference to a none mutable object to
implement the flyweight pattern. It is for a library and its user
interface. So I'm not
On Saturday, 21 May 2016 at 13:17:11 UTC, ag0aep6g wrote:
On 05/21/2016 12:42 PM, chmike wrote:
Rebindable!Info x1, x2 = Infos.one;
Rebindable!(immutable Info) x1, x2 = Infos.one;
Indeed. Thanks. Reading the unit tests in the source code and the
implementation of Rebindable helped.
On Saturday, 21 May 2016 at 17:32:47 UTC, dan wrote:
(This effect could be simulated by making my_var into a
function, but i don't want to do that.)
May I ask why you don't want to do that ?
In D you can call a function without args without ().
So if you write
private int my_var_ = 4; //
After closer examination it seam that the second line with 9 is a
bogus insertion. Removing it should fix the code line table.
app.d 90x43aafb
app.d 110x43aafe
app.d
Hello,
I've notice that gdb was improperly displaying source lines with
disassembled code.
I looked at the assembly to check what is inlined and what not
and the difference between the use of is and == in the machine
code.
I then tested with objdump with a simple program and saw the same
Here you have the object lines from app with the addresses.
./app.d:[++]
app.d 30x43aae8
app.d 50x43aaf0
app.d 70x43aaf7
app.d
On Saturday, 21 May 2016 at 10:42:13 UTC, chmike wrote:
source/app.d(23,27): Error: cannot implicitly convert
expression (one) of type immutable(Obj) to app.Info
Apparently Rebindable doesn't support polymorphism. This is
hopefully fixable.
source/app.d(43,5): Error: 'x1' must be of
On Friday, 20 May 2016 at 17:35:01 UTC, Kagamin wrote:
On Friday, 20 May 2016 at 16:09:54 UTC, chmike wrote:
But I now met another error in my main(). I can't assign the
immutable object to a mutable reference.
Info x1 = MyInfos.one;
Is it possible to define a mutable reference to an
The error message is gone, but I now have another compilation
error message I don't understand.
This is what I have in fact
interface Info { . . . }
class MyInfos {
. . .
protected:
class Obj : Info
{
. . .
}
public:
static immutable Obj one = new immutable Obj(...);
I solved the problem by moving the class Obj definition out of
the class MyInfo.
I still don't understand why I had to do that. In C++ this would
work without problem.
I now have
interface Info {. . .}
class Obj : Info {. . .}
class MyInfos
{
. . .
static immutable Obj one = new
On Friday, 20 May 2016 at 15:43:28 UTC, Marc Schütz wrote:
It looks like your don't actually need `Obj` to be a real
nested class. Try declaring it as `static Obj : Info { }`. This
should work if `Obj`'s methods don't need access to `MyInfo`'s
non-static members.
That worked great. Thank
On Monday, 16 May 2016 at 15:57:52 UTC, Dsby wrote:
you can remove "auto ref". and I remove the "auto ref" in my
use.
if used the "alias T", It can not handle all while when the T
is a delegate.
in C++ std::bind, the arguments order you can sort by used. in
D I do not find how to
Hello,
The nice and handy documentation of dlang doesn't provide any
info on the core.sys. How can I find out all the things that are
in there ?
On Thursday, 12 May 2016 at 10:38:37 UTC, Dsby wrote:
I write one, bind functon to a delegate.
In here:
https://github.com/putao-dev/collie/blob/master/source/collie/utils/functional.d
this is the code:
auto bind(T,Args...)(auto ref T fun,Args args) if
(isCallable!(T))
{
alias
The following code does not compile and I don't understand why.
import std.stdio;
class Data
{
string m = "Hello world !";
}
struct IdxElem(D)
{
bool inUse;
D data;
}
IdxElem!Data[string] idx;
void main()
{
idx["test1"] = IdxElem(true, new Data);
idx["test2"] =
Oops! Stupid of me. There were three bugs in the code.
Correct code is as follow:
import std.stdio;
class Data
{
string m = "Hello world !";
}
struct IdxElem(D)
{
bool inUse;
D data;
}
IdxElem!(Data)[string] idx;
void main()
{
idx["test1"] = IdxElem!Data(true, new Data);
I think you misunderstood the second question.
Here is another attempt with an example.
// function accepting a function as argument
void foo(function void fg(int)) {
fg(5);
}
// A class with a none static method with the same signature as
the argument function of foo
class Bar {
On Wednesday, 4 May 2016 at 06:59:00 UTC, Basile B. wrote:
. . .
void main(string[] args)
{
alias fun = (a) => a.writeln;
auto foo = Foo!fun("hello");
}
Is this equivalent to Foo!(a => a.writeln) or is it required to
split this in two instructions as you did ? I also thought the
Thank you Basile and Teoh.
Hello I have seen the wiki page
https://wiki.dlang.org/Event_system and would like to know the
current status. Is there a working group for this subject ? This
is a topic I'm interested in and did some modest work on some
years ago.
At the bottom of the wiki page there is an innocent
I would like to add that the switchable TLS is only a half backed
solution. It would't work in a multi core context where threads
are truly executing in parallel. Two such threads might get the
same TLS context which would invalidate its implicit predicate.
Another strategy would be to forbit
I have implemented the following class (simplified ;) )
class Foo(K,T) {
this(T delegate (K) factory) { m_factory = factory; }
T delegate (K) m_factory;
T bar(K key) { return m_factory(key); }
}
string dummyFactory(string key) { return "Hello "~key; }
void main()
{
auto
On Thursday, 5 May 2016 at 09:21:04 UTC, rikki cattermole wrote:
Event loops needs to be thread local not per process.
So many API's such as WinAPI for e.g. GUI's have this
requirement in it that its just not worth fighting over.
I don't understand. Do you mean that these event loops are
Excuse the naive question rikki, why does the window event loop
have to be single threaded ? The question is just to expose the
rationale.
Is it to avoid the synchronization overhead to access the window
data ? In this case there is indeed a lot of data. Is there
another reason ?
In some
vibed uses libevent, a C library.
The discussion is regarding a possible pure D equivalent of
libevent.
libasync is an interesting proposal but it is apparently slower
than libevent. I don't know the current status because vibed
improved its performance in the last months.
My initial
Thanks. This does the job but it's not as concise.
Hello,
I failed to find some code example for a template class/struct
that accept a function/delegate as template argument. All
examples I could find use simple value types like int or double.
I piggy bag another question. Defining a function/delegate as
function argument is shown in
Is there an equivalent in D of the C++11 std.bind template class
[http://en.cppreference.com/w/cpp/utility/functional/bind] ?
Here is a blog post showing different examples of its use
https://oopscenities.net/2012/02/24/c11-stdfunction-and-stdbind/
A possible use case is for a callback
It seam that the scope of the event loop we are talking should be
clarified to avoid confusions.
There is the GUI event loop which is generally single threaded
for efficient access to the data structure representing the GUI
content. Single thread also simplifies synchronization and make
The algorithm is to draw a horizontal (or vertical) half line
starting at your point and count the number of polygon edges
crossed by the line. If that number is even, the point is outside
the polygon, if it's odd, the point is inside.
Let (x,y) be the point to test and (x1,y1)(x2,y2) the end
On Tuesday, 26 July 2016 at 15:11:00 UTC, llaine wrote:
Hi guys,
I'm using D since a few month now and I was wondering why
people don't jump onto it that much and why it isn't the "big
thing" already.
Everybody is into javascript nowadays, but IMO even for doing
web I found Vibe.d more
On Wednesday, 27 July 2016 at 10:17:57 UTC, NX wrote:
On Wednesday, 27 July 2016 at 09:28:49 UTC, chmike wrote:
4. Web server && IO performance (see:
https://www.techempower.com/benchmarks or
https://github.com/nanoant/WebFrameworkBenchmark).
Please, these are terribly outdated benchmarks.
On Wednesday, 27 July 2016 at 09:39:18 UTC, Suliman wrote:
...
Big thanks!
Ehm... Now I should add iteration on array of points in first
and second polygon? If it's not hard for you could you show how
it should look please.
Sorry, I may have misunderstood the initial problem. You were
In case you missed it
https://blog.twitch.tv/gos-march-to-low-latency-gc-a6fa96f06eb7#.emwja62y1
On Wednesday, 6 July 2016 at 11:33:53 UTC, Eugene Wissner wrote:
The only reason libev was choosen is that it is the simplest
implementation I know about. A few C files. I had an
educational purpose: I wanted to see how an event loop works on
low level. Asyncio was for me no-go, since I've
On Tuesday, 5 July 2016 at 20:38:53 UTC, Eugene Wissner wrote:
On Tuesday, 5 July 2016 at 08:24:43 UTC, O/N/S wrote:
Hi ("Grüss Gott")
I like the asynchronous events in Javascript.
Is something similar possible in D?
Found Dragos Carp's asynchronous library
On Wednesday, 29 June 2016 at 17:00:49 UTC, Guido wrote:
On Wednesday, 29 June 2016 at 15:40:57 UTC, Andrea Fontana
wrote:
On Wednesday, 29 June 2016 at 15:33:58 UTC, Guido wrote:
The problem is actually much more profound. The classes need
to be declared outside the main() scope. WTF?!?!?!
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