Re: reduce condition nesting
On Thursday, 23 November 2017 at 05:19:27 UTC, Andrey wrote:
Hello, is there way to reduce this condition:
if (c1) {
foo();
} else {
if (c2) {
bar();
} else {
if (c3) {
...
}
}
}
for instance in kotlin it can be replace with this:
when {
c1 -> foo(),
c2 -> bar(),
c3 -> ...
else -> someDefault()
}
do
{
if (c1) { foo(); break;}
if (c2) { bar(); break;}
if (c3) { baz(); break;}
someDefault();
} while (false);
Is d-apt.sourceforge.net functional?
I couldn't find the d-apt-keyring package anywhere root@d9:~# cat /etc/apt/sources.list.d/d-apt.list deb http://master.dl.sourceforge.net/project/d-apt/ d-apt main #APT repository for D root@d9:~# LANG=C apt-get -y --allow-unauthenticated install --reinstall d-apt-keyring Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package d-apt-keyring Cf. http://d-apt.sourceforge.net/ https://sourceforge.net/projects/d-apt/files/dists/d-apt/ Meanwhile I just use http://downloads.dlang.org/releases/2.x/2.077.0/dmd_2.077.0-0_amd64.deb ...
glfwSetDropCallback undefined symbol
DCD and DMD says that the symbol is undefined! However, I look into derelichtGLFW3. It has this symbol defined! It looks like a bug for me!
Re: betterC and noboundscheck
On Wednesday, 22 November 2017 at 16:57:10 UTC, Joakim wrote: On Wednesday, 22 November 2017 at 15:10:40 UTC, Oleg B wrote: [...] betterC is a new feature that's still being worked on and still has holes in it: https://github.com/dlang/dmd/pull/7151 I suggest you open an issue for it on bugzilla, as this sounds like either a hole or at least something that should be documented better: https://issues.dlang.org see also https://github.com/ldc-developers/ldc/pull/2426 (also WiP).
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:07:08 UTC, Tim Hsu wrote:
I am a C++ game developer and I want to give it a try.
It seems "this" in Dlang is a reference instead of pointer.
How can I pass it as void *?
void foo(void *);
class Pizza {
public:
this() {
Pizza newone = this;
// works but newone is actually not this pizza.
foo();
// this does not work..
foo(this);
}
}
void main() {
Pizza pizza = new Pizza();
// this works...
foo();
}
Note that all the examples and advice in this thread apply to
_classes_, not to structs.
The 'this' in a class is a pointer, since classes are reference
types (like the 'this' pointer in C++) so you can cast it to a
void* directly.
The 'this' in a struct is a value, since structs are value types.
So if you want the address of the struct from within one of the
struct's methods you need to use the & operator (then it becomes
a pointer and you can cast it to a void* .
reduce condition nesting
Hello, is there way to reduce this condition:
if (c1) {
foo();
} else {
if (c2) {
bar();
} else {
if (c3) {
...
}
}
}
for instance in kotlin it can be replace with this:
when {
c1 -> foo(),
c2 -> bar(),
c3 -> ...
else -> someDefault()
}
Re: Can I count the of enum's fields at compile time?
On Thursday, 23 November 2017 at 01:34:54 UTC, Ali Çehreli wrote:
On 11/22/2017 05:21 PM, Marc wrote:
On Thursday, 23 November 2017 at 01:04:29 UTC, Jonathan M
Davis wrote:
On Thursday, November 23, 2017 00:58:21 Marc via
Digitalmars-d-learn wrote:
[...]
import std.traits;
enum countOfA = EnumMembers!A.length;
- Jonathna M Davis
This sounds more readable. I was going to write a "function
extension" to enum but I think it isn't really needed. Thank
you too.
As an eponymous template:
enum One { a }
enum Three { a, b, c }
import std.range : EnumMembers;
enum countOf(E) = EnumMembers!E.length;
unittest {
static assert(countOf!One == 1);
static assert(countOf!Three == 3);
}
void main() {
}
Ali
whoa, this is so easy and elegant. I'm falling in love with D.
Thank you too!
Re: Can I count the of enum's fields at compile time?
On 11/22/2017 05:21 PM, Marc wrote:
On Thursday, 23 November 2017 at 01:04:29 UTC, Jonathan M Davis wrote:
On Thursday, November 23, 2017 00:58:21 Marc via Digitalmars-d-learn
wrote:
for example:
enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
enum int countOfA = coutOfFields(A); // 5 fields
import std.traits;
enum countOfA = EnumMembers!A.length;
- Jonathna M Davis
This sounds more readable. I was going to write a "function extension"
to enum but I think it isn't really needed. Thank you too.
As an eponymous template:
enum One { a }
enum Three { a, b, c }
import std.range : EnumMembers;
enum countOf(E) = EnumMembers!E.length;
unittest {
static assert(countOf!One == 1);
static assert(countOf!Three == 3);
}
void main() {
}
Ali
Re: Can I count the of enum's fields at compile time?
On Thursday, 23 November 2017 at 01:04:29 UTC, Jonathan M Davis
wrote:
On Thursday, November 23, 2017 00:58:21 Marc via
Digitalmars-d-learn wrote:
for example:
enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
enum int countOfA = coutOfFields(A); // 5 fields
import std.traits;
enum countOfA = EnumMembers!A.length;
- Jonathna M Davis
This sounds more readable. I was going to write a "function
extension" to enum but I think it isn't really needed. Thank you
too.
Re: Error: 'this' is only defined in non-static member functions
On Thursday, November 23, 2017 00:49:33 Mike Parker via Digitalmars-d-learn
wrote:
> On Wednesday, 22 November 2017 at 22:45:53 UTC, A Guy With a
>
> Question wrote:
> > Out of curiosity, what does static mean in that context? When I
> > think of a static class I think of them in the context of Java
> > or C# where they can't be instantiated and where they are more
> > like namespaces that you can't directly import the contents of.
>
> Actually, they work exactly like Java's static nested classes in
> this context.
>
>
> class OuterClass {
> ...
> static class StaticNestedClass {
> ...
> }
> }
>
> OuterClass.StaticNestedClass nestedObject =
> new OuterClass.StaticNestedClass();
>
> https://docs.oracle.com/javase/tutorial/java/javaOO/nested.html
I thought that that was the case, but my Java is so rusty that I wasn't
sure.
- Jonathan M Davis
Re: Can I count the of enum's fields at compile time?
On Thursday, November 23, 2017 00:58:21 Marc via Digitalmars-d-learn wrote:
> for example:
>
> enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
>
> enum int countOfA = coutOfFields(A); // 5 fields
import std.traits;
enum countOfA = EnumMembers!A.length;
- Jonathna M Davis
Re: Can I count the of enum's fields at compile time?
On Thursday, 23 November 2017 at 01:01:42 UTC, Michael V.
Franklin wrote:
On Thursday, 23 November 2017 at 00:58:21 UTC, Marc wrote:
for example:
enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
enum int countOfA = coutOfFields(A); // 5 fields
https://dlang.org/spec/traits.html#allMembers
enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
enum int countOfA = __traits(allMembers, A).length; // 5 fields
static assert(countOfA == 5);
Mike
This was fast! Thanks
Re: Can I count the of enum's fields at compile time?
On Thursday, 23 November 2017 at 00:58:21 UTC, Marc wrote:
for example:
enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
enum int countOfA = coutOfFields(A); // 5 fields
https://dlang.org/spec/traits.html#allMembers
enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
enum int countOfA = __traits(allMembers, A).length; // 5 fields
static assert(countOfA == 5);
Mike
Can I count the of enum's fields at compile time?
for example:
enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
enum int countOfA = coutOfFields(A); // 5 fields
Re: Error: 'this' is only defined in non-static member functions
On Wednesday, 22 November 2017 at 22:45:53 UTC, A Guy With a
Question wrote:
Out of curiosity, what does static mean in that context? When I
think of a static class I think of them in the context of Java
or C# where they can't be instantiated and where they are more
like namespaces that you can't directly import the contents of.
Actually, they work exactly like Java's static nested classes in
this context.
class OuterClass {
...
static class StaticNestedClass {
...
}
}
OuterClass.StaticNestedClass nestedObject =
new OuterClass.StaticNestedClass();
https://docs.oracle.com/javase/tutorial/java/javaOO/nested.html
Re: Error: 'this' is only defined in non-static member functions
On Thursday, November 23, 2017 00:17:46 A Guy With a Question via Digitalmars-d-learn wrote: > > here as non-static, nested class is associated with a specific > > instance of the class and has access to that class instance via > > its outer member. > > > > - Jonathan M Davis > > Hmmm...now you have me very intrigued. What is a use-case where > you'd want to use a non-static embedded class? Sorry if I'm > asking too many questions. But there's a lot to dig into with > this language. It would make sense with something like the nodes of a linked list if they needed access to the container for some reason. Pretty much any case where a an instance of a nested class is going to be associated with a specific instance of its parent class and needs access to it would be a canditate. It's not that uncommon to see cases in C++ or Java where you'd pass a pointer to the "parent" to an instance of a nested class when it's created, and having outer built-in is kind of like that. Personally, I've never had a use for it. I don't even use classes much in D, since I rarely need inheritance. And as I understand it, most D programs don't use classes very heavily for that very reason. So, I have no idea how common it is to use nested classes in this manner, but I expect that someone has found it useful at some point. I thought that this meaning of static for nested classes came from Java, but it's been a while since I've done much with Java, so I don't know. - Jonathan M Davis
Re: Error: 'this' is only defined in non-static member functions
here as non-static, nested class is associated with a specific instance of the class and has access to that class instance via its outer member. - Jonathan M Davis Hmmm...now you have me very intrigued. What is a use-case where you'd want to use a non-static embedded class? Sorry if I'm asking too many questions. But there's a lot to dig into with this language.
Re: Error: 'this' is only defined in non-static member functions
On Wednesday, November 22, 2017 22:45:53 A Guy With a Question via Digitalmars-d-learn wrote: > On Wednesday, 22 November 2017 at 22:37:46 UTC, Steven > > Schveighoffer wrote: > > On 11/22/17 5:36 PM, Steven Schveighoffer wrote: > >> This allows access to the outer class's members. So you need > >> an instance to instantiate. > >> > >> I bet it's the same for interfaces. > > > > All that being said, the error message is quite lousy. > > > > -Steve > > Yup that worked. Thanks! > > Out of curiosity, what does static mean in that context? When I > think of a static class I think of them in the context of Java or > C# where they can't be instantiated and where they are more like > namespaces that you can't directly import the contents of. A static, nested class does not have access to the class that it's in. It's basically a normal class that's namespaced within another class, whereas non-static, nested class is associated with a specific instance of the class and has access to that class instance via its outer member. https://dlang.org/spec/class.html#nested http://ddili.org/ders/d.en/nested.html Similarly, if a struct, class, or function is nested within a function, and it is not marked with static, then it has access to the function that it's in, whereas if it's marked with static, then it acts more like a normal struct/class/function and does not have access to the function that it's in and is just namespaced within that function. - Jonathan M Davis
Re: Error: 'this' is only defined in non-static member functions
On Wednesday, 22 November 2017 at 22:45:53 UTC, A Guy With a Question wrote: On Wednesday, 22 November 2017 at 22:37:46 UTC, Steven Schveighoffer wrote: On 11/22/17 5:36 PM, Steven Schveighoffer wrote: This allows access to the outer class's members. So you need an instance to instantiate. I bet it's the same for interfaces. All that being said, the error message is quite lousy. -Steve Yup that worked. Thanks! Out of curiosity, what does static mean in that context? When I think of a static class I think of them in the context of Java or C# where they can't be instantiated and where they are more like namespaces that you can't directly import the contents of. Clearly static has a slightly different meaning in D.
Re: Error: 'this' is only defined in non-static member functions
On Wednesday, 22 November 2017 at 22:37:46 UTC, Steven Schveighoffer wrote: On 11/22/17 5:36 PM, Steven Schveighoffer wrote: This allows access to the outer class's members. So you need an instance to instantiate. I bet it's the same for interfaces. All that being said, the error message is quite lousy. -Steve Yup that worked. Thanks! Out of curiosity, what does static mean in that context? When I think of a static class I think of them in the context of Java or C# where they can't be instantiated and where they are more like namespaces that you can't directly import the contents of.
Re: Error: 'this' is only defined in non-static member functions
On 11/22/17 5:36 PM, Steven Schveighoffer wrote: This allows access to the outer class's members. So you need an instance to instantiate. I bet it's the same for interfaces. All that being said, the error message is quite lousy. -Steve
Re: Error: 'this' is only defined in non-static member functions
On 11/22/17 5:19 PM, A Guy With a Question wrote:
I have an interface where I have a classes embedded in it's scope
(trying to create something for the classes that implement the interface
can use for unittesting).
interface IExample
{
// stuff ...
class Tester
{
}
}
I'm trying to make an instance of it like:
auto tester = new IExample.Tester();
And I get the above error.
Hm... not sure how this works for inner classes of Interfaces, but if
it's anything like inner classes of classes, then they have a hidden
'outer' pointer pointing at the owning instance of the class.
This allows access to the outer class's members. So you need an instance
to instantiate.
I bet it's the same for interfaces.
What you probably want is a static class, which will remove that connection:
static class Tester
...
-Steve
Error: 'this' is only defined in non-static member functions
I have an interface where I have a classes embedded in it's scope
(trying to create something for the classes that implement the
interface can use for unittesting).
interface IExample
{
// stuff ...
class Tester
{
}
}
I'm trying to make an instance of it like:
auto tester = new IExample.Tester();
And I get the above error.
Re: ESR on post-C landscape
Also http://ithare.com/chapter-vb-modular-architecture-client-side-programming-languages-for-games-including-resilience-to-reverse-engineering-and-portability/ scroll to the part about language choice.
Re: betterC and noboundscheck
On Wednesday, 22 November 2017 at 15:10:40 UTC, Oleg B wrote:
Hello. I try compile simple example:
import core.stdc.stdio;
import std.algorithm : min;
extern (C) void main()
{
char[256] buf;
buf[] = '\0';
auto str = "hello world";
auto ln = min(buf.length, str.length);
buf[0..ln] = str[0..ln];
printf("%s\n", buf.ptr);
}
rdmd -betterC bettercarray2.d
and get error:
/tmp/.rdmd-1000/rdmd-bettercarray2.d-435C14EC3DAF09FFABF8ED6919B624C1/objs/bettercarray2.o:
In function `main':
bettercarray2.d:(.text.main[main]+0xbc): undefined reference to
`_d_arraycopy'
collect2: error: ld returned 1 exit status
Error: linker exited with status 1
If I understand correctly _d_arraycopy is part of druntime and
it check bounds of array access.
If I add -noboundscheck flag all works fine.
dmd version is 2.076.1
Why -betterC flag not 'include' -noboundscheck flag?
It's bug or in some cases it's useful?
betterC is a new feature that's still being worked on and still
has holes in it:
https://github.com/dlang/dmd/pull/7151
I suggest you open an issue for it on bugzilla, as this sounds
like either a hole or at least something that should be
documented better:
https://issues.dlang.org
Re: interfacing c++
22.11.2017 19:06, Markus пишет: another indicator (as documented) that GC destructor won't work // extern(C++) classes don't have a classinfo pointer in their vtable so the GC can't finalize them https://github.com/dlang/druntime/blob/3d8d4a45c01832fb657c16a656b6e1566d77fb21/src/rt/lifetime.d#L90 annoying :( Markus I've made a guess that more c++ support were added in the last frontend version, well I was wrong
Re: interfacing c++
another indicator (as documented) that GC destructor won't work // extern(C++) classes don't have a classinfo pointer in their vtable so the GC can't finalize them https://github.com/dlang/druntime/blob/3d8d4a45c01832fb657c16a656b6e1566d77fb21/src/rt/lifetime.d#L90 annoying :( Markus
Re: interfacing c++
On Wednesday, 22 November 2017 at 08:43:54 UTC, drug wrote: 22.11.2017 02:12, Markus пишет: What about dtor - you allocate class using D GC but try to destroy it manually - namely this I guess gives you an error in rt_finalize2 because it tries to destroy object that has been destroyed. hmm... I'm not sure. I compiled dmd and it's druntime in debug and I'm stepping through it. Seems there has to be a "ClassInfo" filled with data. In my case it's filled with garbage. So the call ClassInfo.destructor fails, because destructor is an invalid pointer. The GC.collect works, but doesn't call the destructor. https://github.com/dlang/druntime/blob/3d8d4a45c01832fb657c16a656b6e1566d77fb21/src/rt/lifetime.d#L1391 I know constructors and destructors are not supported. And I get that point for move/copy... constructors. But I don't get it for simple construction and destruction. Markus
Re: dmd/ldc failed with exit code -11
On Wednesday, 22 November 2017 at 15:33:46 UTC, Anonymouse wrote:
On Tuesday, 21 November 2017 at 19:22:47 UTC, Anonymouse wrote:
Compiling a debug dmd and running the build command in gdb, it
seems to be a stack overflow at ddmd/dtemplate.d:6241,
TemplateInstance::needsCodegen().
After a lot of trial and error I managed to find /a/ line which
lets it compile under -b plain and release.
void colour(Sink, Codes...)(auto ref Sink sink, const Codes
codes)
{
// Sink is a LockingTextWriter or an Appender!string
// Codes is a tuple of named enum members
foreach (const code; codes)
{
import std.conv : to;
if (++numCodes > 1) sink.put(';');
sink.put((cast(size_t)code).to!string); // <--
}
Change size_t to uint and it compiles, keep it size_t and the
compiler segfaults. Tested on two machines, both running
up-to-date Arch linux, both with dmd and ldc.
The bug is too ephemeral to reduce well, if a thing like order
of arguments matters.
If this is an emergent property of the rest of the program, and
the size_t merely fells the house of cards, is it even worth
reporting when I can't reduce it?
You did a good investigation and I still think it's important to
report it.
I managed to find a few other cases where people were having
issues with needsCodegen:
https://github.com/ldc-developers/ldc/issues/2168#issuecomment-312709632
https://github.com/ldc-developers/ldc/issues/2336
https://github.com/ldc-developers/ldc/issues/2022#issuecomment-288481397
https://github.com/ldc-developers/ldc/issues/1297#issuecomment-184770787
So there's enough evidence that there's a bug somewhere around
that part of the compiler and we should gather good test cases to
narrow down the problem.
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:34:53 UTC, Adam D. Ruppe wrote: No, in both cases, if you do as I say, you will be passing the same address. I was referring to his version of the main function that used &. But yes, if you do a cast instead it works just as you say.
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:36:22 UTC, Adam D. Ruppe
wrote:
On Wednesday, 22 November 2017 at 15:31:36 UTC, Tim Hsu wrote:
It seems in D, reference has its own address, am I right?
unlike c++
The local variable does have its own address. Do not take its
address - avoid or
Just cast the ref itself.
In D, a class this or Object variable is already like a C++
Foo*. If you & that, you get a Foo** - not what you want in
most cases.
Thanks after doing some experiment I guess I finally understand
class App {
@property void *ptr() {
return cast(void *)(this);
}
}
void printaddr(void *ptr)
{
writeln(ptr);
}
void main()
{
Pizza pza = new Pizza("XD");
Pizza pza2 = pza;
printaddr(pza.ptr);
printaddr(pza2.ptr);
printaddr();
printaddr();
}
Result:
A32000
A32000
19FDB0
19FDB4
Conclusion:
pza and pza2 is two different reference variable refer to same
new-ed object.
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:31:36 UTC, Tim Hsu wrote: It seems in D, reference has its own address, am I right? unlike c++ In case of classes, yes. But I think function parameter references do not (or rather, of course they have since they exist in memory but it's hidden). Not sure though.
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:23:58 UTC, Tim Hsu wrote: m_window = glfwCreateWindow(); glfwSetWindowUserPointer(m_window, cast(void *)()); That that & out of there! glfwSetWindowUserPointer(m_window, cast(void *)(this)); without the &, you are fine. Then, on the other side, you cast back. Again, do NOT dereference it, just cast it: App app = cast(App) user_ptr;
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:31:36 UTC, Tim Hsu wrote: It seems in D, reference has its own address, am I right? unlike c++ The local variable does have its own address. Do not take its address - avoid or Just cast the ref itself. In D, a class this or Object variable is already like a C++ Foo*. If you & that, you get a Foo** - not what you want in most cases.
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:27:27 UTC, Dukc wrote: It's worth noting that you will still be passing different addresses to foo(void*) because classes are reference types in D (structs are not). In the constructor you're passing the address of the class object itself, but in the main function you're passing the address of the reference. No, in both cases, if you do as I say, you will be passing the same address. You cast the reference itself. Do NOT use the & operator at any point with class objects in D (unless you legit know what you are doing). Just plain cast it: `cast(void*) this` // ok. gets address of class object itself `Object o; foo(cast(void*) o);` // also ok, does same thing `cast(void*) ` // NOT OK! DO NOT DO THIS address of a local `cast(void*) `// NOT OK! DO NOT DO THIS address of a local
Re: dmd/ldc failed with exit code -11
On Tuesday, 21 November 2017 at 19:22:47 UTC, Anonymouse wrote:
Compiling a debug dmd and running the build command in gdb, it
seems to be a stack overflow at ddmd/dtemplate.d:6241,
TemplateInstance::needsCodegen().
After a lot of trial and error I managed to find /a/ line which
lets it compile under -b plain and release.
void colour(Sink, Codes...)(auto ref Sink sink, const Codes codes)
{
// Sink is a LockingTextWriter or an Appender!string
// Codes is a tuple of named enum members
foreach (const code; codes)
{
import std.conv : to;
if (++numCodes > 1) sink.put(';');
sink.put((cast(size_t)code).to!string); // <--
}
Change size_t to uint and it compiles, keep it size_t and the
compiler segfaults. Tested on two machines, both running
up-to-date Arch linux, both with dmd and ldc.
The bug is too ephemeral to reduce well, if a thing like order of
arguments matters.
If this is an emergent property of the rest of the program, and
the size_t merely fells the house of cards, is it even worth
reporting when I can't reduce it?
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:27:27 UTC, Dukc wrote: On Wednesday, 22 November 2017 at 15:17:33 UTC, Adam D. Ruppe wrote: On Wednesday, 22 November 2017 at 15:07:54 UTC, Stefan Koch wrote: will do. Even if it were an lvalue, that would be the address of a local. You should basically NEVER do that with D classes. Just `cast(void*) this` if you must pass it to such a function. It's worth noting that you will still be passing different addresses to foo(void*) because classes are reference types in D (structs are not). In the constructor you're passing the address of the class object itself, but in the main function you're passing the address of the reference. It seems in D, reference has its own address, am I right? unlike c++
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:23:58 UTC, Tim Hsu wrote: I am afraid what will happen when casting this reference to void * a ref is a ptr. The cast will produce a ptr which is valid as long as the ref is valid.
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:17:33 UTC, Adam D. Ruppe wrote: On Wednesday, 22 November 2017 at 15:07:54 UTC, Stefan Koch wrote: will do. Even if it were an lvalue, that would be the address of a local. You should basically NEVER do that with D classes. Just `cast(void*) this` if you must pass it to such a function. It's worth noting that you will still be passing different addresses to foo(void*) because classes are reference types in D (structs are not). In the constructor you're passing the address of the class object itself, but in the main function you're passing the address of the reference.
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:17:33 UTC, Adam D. Ruppe
wrote:
On Wednesday, 22 November 2017 at 15:07:54 UTC, Stefan Koch
wrote:
will do.
Even if it were an lvalue, that would be the address of a
local. You should basically NEVER do that with D classes.
Just `cast(void*) this` if you must pass it to such a function.
I am afraid what will happen when casting this reference to void *
glfwSetWindowUserPointer gives us a chance to provide a pointer
to userdata. so that in callback function, we can retrieve the
data and don't have to declare global variable.
class App {
public this() {
m_window = glfwCreateWindow();
glfwSetWindowUserPointer(m_window, cast(void *)());
}
}
How do I use this function in Dlang?
sorry for my bad english.
Re: betterC and noboundscheck
On Wednesday, 22 November 2017 at 15:10:40 UTC, Oleg B wrote: Why -betterC flag not 'include' -noboundscheck flag? -noboundscheck is extremely harmful. If -betterC implied that, it would no longer be a better C, it would just be the same buggy C. The compiler should perhaps inline the bounds check so it doesn't need the druntime function, but it certainly shouldn't skip it.
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:07:54 UTC, Stefan Koch wrote: will do. Even if it were an lvalue, that would be the address of a local. You should basically NEVER do that with D classes. Just `cast(void*) this` if you must pass it to such a function.
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:14:32 UTC, Stefan Koch wrote: On Wednesday, 22 November 2017 at 15:11:08 UTC, Tim Hsu wrote: On Wednesday, 22 November 2017 at 15:07:54 UTC, Stefan Koch will do. I've tried it in the first place. ... Error: this is not an lvalue In that case casting to void* should be fine. But..The compiler still does not produce the executable... foo(); app.d(17): Error: this is not an lvalue
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:11:08 UTC, Tim Hsu wrote: On Wednesday, 22 November 2017 at 15:07:54 UTC, Stefan Koch will do. I've tried it in the first place. ... Error: this is not an lvalue In that case casting to void* should be fine.
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:07:54 UTC, Stefan Koch wrote:
On Wednesday, 22 November 2017 at 15:07:08 UTC, Tim Hsu wrote:
I am a C++ game developer and I want to give it a try.
It seems "this" in Dlang is a reference instead of pointer.
How can I pass it as void *?
void foo(void *);
class Pizza {
public:
this() {
Pizza newone = this;
// works but newone is actually not this pizza.
foo();
// this does not work..
foo(this);
}
}
void main() {
Pizza pizza = new Pizza();
// this works...
foo();
}
will do.
I've tried it in the first place.
...
Error: this is not an lvalue
betterC and noboundscheck
Hello. I try compile simple example:
import core.stdc.stdio;
import std.algorithm : min;
extern (C) void main()
{
char[256] buf;
buf[] = '\0';
auto str = "hello world";
auto ln = min(buf.length, str.length);
buf[0..ln] = str[0..ln];
printf("%s\n", buf.ptr);
}
rdmd -betterC bettercarray2.d
and get error:
/tmp/.rdmd-1000/rdmd-bettercarray2.d-435C14EC3DAF09FFABF8ED6919B624C1/objs/bettercarray2.o:
In function `main':
bettercarray2.d:(.text.main[main]+0xbc): undefined reference to
`_d_arraycopy'
collect2: error: ld returned 1 exit status
Error: linker exited with status 1
If I understand correctly _d_arraycopy is part of druntime and it
check bounds of array access.
If I add -noboundscheck flag all works fine.
dmd version is 2.076.1
Why -betterC flag not 'include' -noboundscheck flag?
It's bug or in some cases it's useful?
Re: Passing this to void *
On Wednesday, 22 November 2017 at 15:07:08 UTC, Tim Hsu wrote:
I am a C++ game developer and I want to give it a try.
It seems "this" in Dlang is a reference instead of pointer.
How can I pass it as void *?
void foo(void *);
class Pizza {
public:
this() {
Pizza newone = this;
// works but newone is actually not this pizza.
foo();
// this does not work..
foo(this);
}
}
void main() {
Pizza pizza = new Pizza();
// this works...
foo();
}
will do.
Passing this to void *
I am a C++ game developer and I want to give it a try.
It seems "this" in Dlang is a reference instead of pointer.
How can I pass it as void *?
void foo(void *);
class Pizza {
public:
this() {
Pizza newone = this;
// works but newone is actually not this pizza.
foo();
// this does not work..
foo(this);
}
}
void main() {
Pizza pizza = new Pizza();
// this works...
foo();
}
Re: writeln, alias this and dynamic arrays.
Thank you all for the helpful responses. I will read more about ranges.
Re: Having "in" for arrays
On Wednesday, 22 November 2017 at 10:32:48 UTC, lobo wrote:
On Wednesday, 22 November 2017 at 09:36:43 UTC, Dukc wrote:
On Wednesday, 22 November 2017 at 08:03:50 UTC, Fra Mecca
wrote:
void main()
{
auto v = ["r", "i", "o"];
assert ("r" in v);
}
Also note that even if it wereimplemented, you search for 'r'
instead of "r". "r" is a string, but you would want to search
for a char.
Isn't 'v' an array of strings? If it were a array of chars,
then the search would be 'r'.
bye,
lobo
Oops, you're correct. My bad.
Re: Having "in" for arrays
On Wednesday, 22 November 2017 at 09:36:43 UTC, Dukc wrote:
On Wednesday, 22 November 2017 at 08:03:50 UTC, Fra Mecca wrote:
void main()
{
auto v = ["r", "i", "o"];
assert ("r" in v);
}
Also note that even if it wereimplemented, you search for 'r'
instead of "r". "r" is a string, but you would want to search
for a char.
Isn't 'v' an array of strings? If it were a array of chars, then
the search would be 'r'.
bye,
lobo
Re: Having "in" for arrays
On Wednesday, 22 November 2017 at 08:03:50 UTC, Fra Mecca wrote:
void main()
{
auto v = ["r", "i", "o"];
assert ("r" in v);
}
Also note that even if it wereimplemented, you search for 'r'
instead of "r". "r" is a string, but you would want to search for
a char.
Re: Having "in" for arrays
On Wednesday, November 22, 2017 08:03:50 Fra Mecca via Digitalmars-d-learn
wrote:
> Why doesn't D have a in keyword for arrays?
>
> The docs explains that you can use in only for associative arrays
> but I don't see the reasons for such decision.
>
>
> Example code:
>
> void main()
> {
> auto v = ["r", "i", "o"];
> assert ("r" in v);
> }
>
>
> That currently fails:
> main.d(4): Error: incompatible types for (("r") in (v)): 'string'
> and 'string[]'
in is supposed to be at worst O(log n), whereas to do the operation for an
array would be O(n). If you want to search for a specific element in an
array than use std.algorithm.find or std.algorithm.canFind.
- Jonathan M Davis
Re: interfacing c++
22.11.2017 02:12, Markus пишет: snip I could do the instancing/destruction by functions and write a custom d class that calls these methods in this()/~this(). This is what I used to do as special members like ctor/dtor did not supported in D before, but your example of using ctor is interesting. What about dtor - you allocate class using D GC but try to destroy it manually - namely this I guess gives you an error in rt_finalize2 because it tries to destroy object that has been destroyed.
Re: interfacing c++
On Wednesday, 22 November 2017 at 08:29:26 UTC, MGW wrote: Possibly it will be interesting https://pp.userapi.com/c639524/v639524332/60240/uH3jnxrchik.jpg
Re: interfacing c++
On Tuesday, 21 November 2017 at 23:12:33 UTC, Markus wrote: hi, im trying to interface a cpp class. I'd like to interface a bigger library and I'm trying to figure out the minimum effort. Possibly it will be interesting https://www.youtube.com/watch?v=HTgJaRRfLPk
