Re: Pointer to private structure
On Monday, 19 December 2016 at 06:21:10 UTC, ketmar wrote: i bet that just trying this with D compiler will take less time than writing forum post. I did try but it seems to give compilation failure... Let me try once more and I will get back with more details.
Re: Pointer to private structure
i bet that just trying this with D compiler will take less time than writing forum post.
Re: Pointer to private structure
On Monday, 19 December 2016 at 05:51:09 UTC, Nikhil Jacob wrote: In C, we can define a struct without body in an include file and use pointer to that structure For examples in public header file. struct data; data* new_data(); We can then define the elements of struct data privately inside the implementation of library. Can we do this in D without using void* ? Yes.
Pointer to private structure
In C, we can define a struct without body in an include file and use pointer to that structure For examples in public header file. struct data; data* new_data(); We can then define the elements of struct data privately inside the implementation of library. Can we do this in D without using void* ?
Re: Returning structs from COM
On Saturday, 3 December 2016 at 09:51:00 UTC, John C wrote:
Some DirectX methods return structs by value, but when I try
calling them I either get garbage or an access violation.
Usually COM methods return structs by pointer as a parameter,
but these are returning the struct as the actual return value,
as in this definition:
extern(Windows):
struct D2D1_SIZE_F { float width, height; }
interface ID2D1Bitmap : ID2D1Image {
D2D1_SIZE_F GetSize();
}
If I rewrite GetSize to return by pointer as a parameter, it
appears to work and I get the correct width and height without
an AV being thrown. And I can add a helper method that returns
by value:
interface ID2D1Bitmap : ID2D1Image {
void GetSize(D2D1_SIZE_F* size);
final D2D1_SIZE_F GetSize() {
D2D1_SIZE_F size;
GetSize();
return size;
}
}
But does anyone know why the original definition works in C++
but not D? Is it a bug? (I'm compiling with -m64.)
most likely due to this
https://issues.dlang.org/show_bug.cgi?id=16527
and that is annoying. i tried ldc2 1.1.beta6 and dmd 2.072.1 both
x86 and x64 and it crashes anyways, sooner or later.
btw if you make call with return pointer instead of value it can
probably messed up your stack already and crash any moment later.
in my DirectX bindings i used to return ref struct(though i think
this is dirty hack), and it was working until recent.
Re: sort, .array and folding on immutable data (finding most common character in column of matrix)
On Sunday, 18 December 2016 at 22:26:50 UTC, Ali wrote:
Hey, so I have this data file that has a list of a string of
characters separated by new lines. The task is to find the most
common letter in each column. Ie if file is:
abc
axy
cxc
Then the letters are a (column 1), x and c.
I've written the code to do this at compile time. But I have a
few questions about sorting, immutablity casting and the need
to use .array. The code follows:
==
import std.stdio, std.range, std.algorithm;
// Line 1
static immutable data =
import("data_06.txt").split("\n").transposed.map!"a.array.sort().group.array".array;
// Line 2
alias T = typeof(data[0][0]);
auto redux(T[] charData) {
return charData.fold!((a, b) {
return a[1] > b[1] ? a : typeof(a)(b[0], b[1]);
})(T.init);
}
// Line 3
static immutable word = data.map!redux.array.map!"a[0]".array;
void main() {
word.writeln;
}
==
Well mostly I'm looking for how to simplify this even further.
So any hints there would be awesome.
And, there're a few questions I have about the code (I guess
mainly because of my of my lack of understanding of the type
system)
1. The first line with the splitting, I need to use .array
three times. The last one I understand is because on "line 2" I
alias T as the type of the data, and if I don't call .array
then it's a MapResult type which has no opIndex. Yes?
2. On "line 1" I have to call .array.sort(). Why can't I just
call .sort() on the transposed rows?
Because sort requires a random access range.
3. If I call .sort (without parenthesis) I get a compiler
error. What up with that?
Unfortunately arrays have a builtin property sort that for some
reason takes precedence of std.algorithm.sort when called without
(). The compiler error is probably because .sort is a mutating
operation and you're working with immutable data.
4. On "line 3" I call map with the free function "redux". In
this function, if I return just "a", it's all good. If I return
"b", then I get "Incompatible function/seed/element:
__lambda2/Tuple!(dchar, uint)/immutable(Tuple!(dchar, uint))".
So my seed is not immutable, but the elements of "data" are. I
can understand that. But how do I work around it without having
to do "typeof(a)(b[0], b[1])" ?
Try
})(ImmutableOf!T.init);
or use the seedless version of fold.
may need to import std.traits(?)
5. Is there anyway to get rid of the the "alias" I have in the
code and just use an inline lambda in my map call on "line 3"?
does `data.map!fold!"a[1] > b[1] ? a : b".map!"a[0]".array;` work?
sort, .array and folding on immutable data (finding most common character in column of matrix)
Hey, so I have this data file that has a list of a string of
characters separated by new lines. The task is to find the most
common letter in each column. Ie if file is:
abc
axy
cxc
Then the letters are a (column 1), x and c.
I've written the code to do this at compile time. But I have a
few questions about sorting, immutablity casting and the need to
use .array. The code follows:
==
import std.stdio, std.range, std.algorithm;
// Line 1
static immutable data =
import("data_06.txt").split("\n").transposed.map!"a.array.sort().group.array".array;
// Line 2
alias T = typeof(data[0][0]);
auto redux(T[] charData) {
return charData.fold!((a, b) {
return a[1] > b[1] ? a : typeof(a)(b[0], b[1]);
})(T.init);
}
// Line 3
static immutable word = data.map!redux.array.map!"a[0]".array;
void main() {
word.writeln;
}
==
Well mostly I'm looking for how to simplify this even further. So
any hints there would be awesome.
And, there're a few questions I have about the code (I guess
mainly because of my of my lack of understanding of the type
system)
1. The first line with the splitting, I need to use .array three
times. The last one I understand is because on "line 2" I alias T
as the type of the data, and if I don't call .array then it's a
MapResult type which has no opIndex. Yes?
2. On "line 1" I have to call .array.sort(). Why can't I just
call .sort() on the transposed rows?
3. If I call .sort (without parenthesis) I get a compiler error.
What up with that?
4. On "line 3" I call map with the free function "redux". In this
function, if I return just "a", it's all good. If I return "b",
then I get "Incompatible function/seed/element:
__lambda2/Tuple!(dchar, uint)/immutable(Tuple!(dchar, uint))". So
my seed is not immutable, but the elements of "data" are. I can
understand that. But how do I work around it without having to do
"typeof(a)(b[0], b[1])" ?
5. Is there anyway to get rid of the the "alias" I have in the
code and just use an inline lambda in my map call on "line 3"?
Re: meaning of "auto ref const"?
On Sunday, 18 December 2016 at 14:32:08 UTC, kinke wrote: TypeInfo_Struct apparently requires (or used to require) an `int opCmp(ref const T rhs)` overload, i.e., a version taking the rhs lvalue argument by reference (see https://dlang.org/spec/operatoroverloading.html#compare). Note that there are other overloads afterwards which take the rhs argument by value, thereby allowing rhs rvalues too. Thank you for your complementary answer and explanation. All these look less strange to me now.
Re: meaning of "auto ref const"?
On Sunday, 18 December 2016 at 14:25:04 UTC, Basile B. wrote: ... As you can see, auto ref is more flexible with the parameter. This make sense for templated functions. Thank you for your detailed answer, things are perfectly clear now. Also sorry for the doc linksI should have found it before asking my question.
Re: meaning of "auto ref const"?
On Sunday, 18 December 2016 at 13:14:08 UTC, Picaud Vincent wrote:
bool opEquals()(auto ref const BigInt y) const pure @nogc
{
return sign == y.sign && y.data == data;
}
my problem is that I do not understand the role/meaning of
"auto" in this context.
See https://dlang.org/spec/template.html#auto-ref-parameters.
It's used to end up with an `opEquals(ref const BigInt y)` for
lvalue args (passed by reference) and with an `opEquals(const
BigInt y)` for rvalue args (passed by value => implicitly moved
in D (as they are rvalues)).
Moreover in the opCmp code, "auto" is not present anymore,
which is an extra source of confusions for me.
int opCmp(ref const BigInt y) pure nothrow @nogc const
{
// Simply redirect to the "real" opCmp implementation.
return this.opCmp!BigInt(y);
}
TypeInfo_Struct apparently requires (or used to require) an `int
opCmp(ref const T rhs)` overload, i.e., a version taking the rhs
lvalue argument by reference (see
https://dlang.org/spec/operatoroverloading.html#compare). Note
that there are other overloads afterwards which take the rhs
argument by value, thereby allowing rhs rvalues too.
Re: meaning of "auto ref const"?
On Sunday, 18 December 2016 at 13:14:08 UTC, Picaud Vincent wrote:
Reading std/bigint.d code:
https://github.com/dlang/phobos/blob/00c1cc3b0d354363793c8b419ce84da722578138/std/bigint.d#L589
I have seen this:
bool opEquals()(auto ref const BigInt y) const pure @nogc
{
return sign == y.sign && y.data == data;
}
my problem is that I do not understand the role/meaning of
"auto" in this context.
With auto ref, the parameter can be either a LValue or a RValue.
When passing a struct as auto ref, it's taken as ref.
for example:
struct Foo{this(this){writeln("copy");}}
struct Bar{@disable this(this);}
void testAsRef(T)(ref T t){}
void testAsValue(T)(T t){}
void testRefOrValue(T)(auto ref T t){}
Foo foo;
Bar bar;
testAsRef(1); // error 1 is not ref
testAsRef(foo); // ok, not copied
testAsRef(bar); // ok, not copied
testAsValue(1); // ok
testAsValue(foo); // ok but copied
testAsValue(bar); // error, could only be copied but postblit is
disabled
testRefOrValue(1); // ok, not taken as ref
testRefOrValue(foo); // ok, not copied
testRefOrValue(bar); // ok, taken as ref
As you can see, auto ref is more flexible with the parameter.
This make sense for templated functions.
meaning of "auto ref const"?
Reading std/bigint.d code:
https://github.com/dlang/phobos/blob/00c1cc3b0d354363793c8b419ce84da722578138/std/bigint.d#L589
I have seen this:
bool opEquals()(auto ref const BigInt y) const pure @nogc
{
return sign == y.sign && y.data == data;
}
my problem is that I do not understand the role/meaning of "auto"
in this context.
Moreover in the opCmp code, "auto" is not present anymore, which
is an extra source of confusions for me.
int opCmp(ref const BigInt y) pure nothrow @nogc const
{
// Simply redirect to the "real" opCmp implementation.
return this.opCmp!BigInt(y);
}
What is the rational?
-
Another interrogation for me, who come from C++, is how to
translate into D:
template void foo(T&& t);
Re: Using tango with dub
Have you seen https://github.com/economicmodeling/containers it has a HashSet http://economicmodeling.github.io/containers/containers/hashset.HashSet.html Just curious, how is it different from Tango's implementation?
Re: Using tango with dub
On 2016-12-17 21:15, bauss wrote: I thought Tango was obsolete a long time ago. It's a third party library like any other library. -- /Jacob Carlborg
Re: Using tango with dub
On 2016-12-18 10:43, albert-j wrote: Try an older version. Before resorting to that, I am also trying to "dub build --compiler=gdc". Getting different types of errors: ../../../.dub/packages/tango-1.0.3_2.068/tango/tango/math/IEEE.d:614:17: error: instead of C-style syntax, use D-style syntax 'real[3][] vals' [-Werror] static real vals[][3] = // x,frexp,exp ... ^ cc1d: all warnings being treated as errors I tried to suppress the errors by adding buildRequirements:["allowWarnings", "silenceWarnings"] to dub.json, but no luck. Is it possible to get around them? I don't know. Seems like the -Werror flag is passed, somewhere. -- /Jacob Carlborg
Re: Using tango with dub
Try an older version. Before resorting to that, I am also trying to "dub build --compiler=gdc". Getting different types of errors: ../../../.dub/packages/tango-1.0.3_2.068/tango/tango/math/IEEE.d:614:17: error: instead of C-style syntax, use D-style syntax 'real[3][] vals' [-Werror] static real vals[][3] = // x,frexp,exp ... ^ cc1d: all warnings being treated as errors I tried to suppress the errors by adding buildRequirements:["allowWarnings", "silenceWarnings"] to dub.json, but no luck. Is it possible to get around them?
