is Dlang support Uniform initialization like c++
struct Point {
int x;
int y;
this(int x, int y) { this.x =x; this.y=y;}
}
void addPoint(Point a, Point b) {
...
}
How too wirte this: addPoint({4,5}, {4,6})
Re: Is remove safe using foreach
is foreach Syntactic sugar?, like for-range in C++, if it is, compiler how implement
Is remove safe using foreach
```
int[string] aa = ["ok":1, "aaa":2, "ccc":3, "ddd":4];
foreach (k ; aa.byKey)
{
if (k == "aaa") {
aa.remove(k);
aa["ww"] = 33;
}
if (k == "ww") {
aa.remove(k);
aa["vv"] = 33;
}
}
writeln(aa); // output ["ok":1, "ddd":4, "vv":33, "ccc":3] is ok
```
How to cross build a RISC-V target betterC code using LDC on x86-64 machine
I have used to ldc2(1.20.1) on x86-64 laptop with `ldc2 -c -betterC -mtriple=riscv64 betterC.d -v ` but comiple is failed. output: ``` binary/usr/bin/ldc2 version 1.20.1 (DMD v2.090.1, LLVM 10.0.0) config/etc/ldc2.conf (riscv64) 'generic' is not a recognized processor for this target (ignoring processor) 'generic' is not a recognized processor for this target (ignoring processor) ... importcore.stdc.time (/usr/lib/ldc/x86_64-linux-gnu/include/d/core/stdc/time.d) semantic betterC /usr/lib/ldc/x86_64-linux-gnu/include/d/core/stdc/time.d(151): Error: undefined identifier time_t, did you mean function time? /usr/lib/ldc/x86_64-linux-gnu/include/d/core/stdc/time.d(151): Error: undefined identifier time_t, did you mean function time? /usr/lib/ldc/x86_64-linux-gnu/include/d/core/stdc/time.d(153): Error: undefined identifier time_t, did you mean function time? /usr/lib/ldc/x86_64-linux-gnu/include/d/core/stdc/time.d(153): Error: undefined identifier tm ```
Re: Now can build and run d on RISC-V arch?
On Sunday, 6 June 2021 at 04:53:08 UTC, Nicholas Wilson wrote: On Sunday, 6 June 2021 at 04:14:20 UTC, lili wrote: I want learn RISC-V and write a simple kernel on it using d. but can not find any support about RISC-V. LDC can compile for riscv 32 and 64 bit. https://github.com/ldc-developers/ldc/releases/tag/v1.26.0 use `-mtriple=riscv32` or `-mtriple=riscv32` as the arch for the triple. I'm not sure what you should put for the `os` and `env` fields of the triple. The vendor field can be left as `unknown`. Do a search for triples people use to target riscv and use that if the above doesn't work. Thanks a lot.
Now can build and run d on RISC-V arch?
I want learn RISC-V and write a simple kernel on it using d. but can not find any support about RISC-V.
Why Dlang use parsing expression grammar (PEG) parser not BNF?
Hi: I want implementation Lua on D, I find that a PEG parser https://github.com/PhilippeSigaud/Pegged why do not use BNF parser. Is PEG better than BNF?
Is there any writeln like functions without GC?
Hi: why writeln need GC?
Re: About the in expression, Why can't use with array.
On Friday, 25 October 2019 at 21:06:53 UTC, IGotD- wrote: On Friday, 25 October 2019 at 20:44:18 UTC, Dennis wrote: On Friday, 25 October 2019 at 19:49:05 UTC, Ali Çehreli wrote: I'm still not completely sold on the whole idea though because it's not a clear win. Do others see other advantages in other places like templates? For example, could templates really be written generically for arrays and associative arrays? I'm personally not concerned about generic code. - The semantics of `in` aren't very well defined anyways. - Those who write templates like that (hopefully) know what they're doing, they'll figure it out ;) - I can't think of situations where you actually want to write code that generically works on both arrays and associative arrays like that. (Though if anyone knows one, please share, I'm interested.) I'm more concerned about the repeated reports of users being surprised that `in` doesn't work like they expect. In Python, the expression `3 in [2, 3, 4]` returns a boolean, and in D you can do `bool b = 15 in iota(10, 20)` because the operator is overloaded in Phobos for iota; But as far as actual language support, `in` is only defined for associative arrays: https://dlang.org/spec/expression.html#InExpression It returns a pointer which can be used in an if-statement, but also to read/modify the value. So should `in` on arrays do the same? It would be consistent, but usage of raw pointers is discouraged with the advent of scope and ref etc. Also you can't implicitly convert a pointer to a boolean. Should it be a boolean then? That means part of the result of the linear search is discarded, making `in` less flexible. So maybe we should leave it for now, and put a small explanation in the error message. I'm also not so fond of that "in" operator returns a pointer which is bad fit for arrays and possibly many other container algorithms as well. I think the best would be that it would return an optional of type T and T would be user defined. For associative arrays, a pointer or a reference to the element. For arrays the index of that element would suitable. Also overloading would be nice so that "in" operator could return several possible optional types, not sure if that would be possible though. I argee with your talk, lanuage designer need keep consistent that the 'in' semantics. or not support 'in' key word. Don't assumption that how user use it.
Can not understand this code.
Hi:
What is the alias Min = xxx mean? why need defined a alias Min in
Min template?
```
template Min(alias pred, Args...)
if (Args.length > 0 && __traits(isTemplate, pred))
{
static if (Args.length == 1)
{
alias Min = Alias!(Args[0]);
}
else static if (isLess!(pred, Args[1], Args[0]))
{
alias Min = Min!(pred, Args[1], Args[2 .. $]);
}
else
{
alias Min = Min!(pred, Args[0], Args[2 .. $]);
}
}
```
Re: About the in expression, Why can't use with array.
On Thursday, 24 October 2019 at 22:40:31 UTC, Jonathan M Davis wrote: On Thursday, October 24, 2019 7:04:56 AM MDT Paul Backus via Digitalmars-d- learn wrote: On Thursday, 24 October 2019 at 12:58:11 UTC, lili wrote: > Hi: >In Dlang where is strange design. The in expression can > only > > use to associative array, why array can not use in > expression. Checking for the presence of an item in an array requires a linear search. You can do it with std.algorithm.searching.canFind: https://dlang.org/phobos/std_algorithm_searching.html#.canFind In particular, the reason that linear search is considered unacceptable for in is so that generic code can rely on its performance. The idea is that types shouldn't implement the in operator unless they can do so with O(log n) or better (O(log n) being what it costs to get to an item in a balanced binary tree like a red-black tree). That way, when you calculate the complexity of any algorithm using in, you can assume that it's O(log n) at worst. Having it be O(n) instead (like it would be for an array) would drastically increase the complexity of the algorithm and make it take much longer when processing a large number of items. And the standard library provides functions like canFind or find for finding elements in an array, so having in work with arrays wouldn't add any functionality. It would basically just change the syntax you'd use for finding an element in an array. - Jonathan M Davis This reason somewhat farfetched， Think about that if this reason is right， the operator overload can not use。 because same operator on different type expression same mean but different implementation and complexity。 so why operator overload can don't care about implementation but 'in' operator need。
About the in expression, Why can't use with array.
Hi: In Dlang where is strange design. The in expression can only use to associative array, why array can not use in expression.
What do you think about About C++20 Concepts?
Hi: In C++20 Concepts is great idear. but I thinks it is too difficult to write. I like Rust traits simple and elegancy.
Why dynamic array is InputRange but static array not.
Hi: in phobos/std/range/primitives.d has this code ``` static assert( isInputRange!(int[])); static assert( isInputRange!(char[])); static assert(!isInputRange!(char[4])); static assert( isInputRange!(inout(int)[])); ``` but the dynamic array and static array neither not has popFront/front/empty. https://dlang.org/spec/arrays.html#array-properties properties
what is the mean that call function start with a dot.
Hi： yesterday I saw some d code， where is an .fn() call syntax, what is it mean.
Re: Is there has an pdf document for Phobos.
On Wednesday, 4 September 2019 at 04:21:10 UTC, Mike Parker wrote: On Wednesday, 4 September 2019 at 03:07:18 UTC, lili wrote: Hi: For some reason it too slow that some times i visited dlang.org, Can admin make a pdf document for download. Documentation is installed with the compiler. Thanks
Re: Is there has an pdf document for Phobos.
On Wednesday, 4 September 2019 at 04:21:10 UTC, Mike Parker wrote: On Wednesday, 4 September 2019 at 03:07:18 UTC, lili wrote: Hi: For some reason it too slow that some times i visited dlang.org, Can admin make a pdf document for download. Documentation is installed with the compiler. How to open it?
Is there has an pdf document for Phobos.
Hi: For some reason it too slow that some times i visited dlang.org, Can admin make a pdf document for download.
Re: How stdin.readf ignore space char?
On Tuesday, 3 September 2019 at 13:21:16 UTC, a11e99z wrote: On Tuesday, 3 September 2019 at 12:55:29 UTC, lili wrote: Hi guys: input is two line, first line is a number n and second line is n float point number， e.g. 3 1.1 2.2 3.3 how use stdin.readf get all number. https://dlang.org/library/std/stdio/readf.html see example string d = "3.43.3 "; double a; double b; //formattedRead(d,"%f %f", , ); d.readf!" %s %s"(a,b);//hug writeln(a,b);
How stdin.readf ignore space char?
Hi guys:
input is two line, first line is a number n and second line is
n float point number，
e.g. 3
1.1 2.2 3.3
how use stdin.readf get all number. i code below but not work
well.
int n;
stdin.readf!"%d\n"(n);
writeln("read n:",n);
foreach (i; 0..n)
{
double x;
stdin.readf!"%f"(x); //only return first number,
why？
writeln(x);
}
Re: How to learn Phobos，Phbos hard to used for me.
On Wednesday, 28 August 2019 at 12:32:59 UTC, Andre Pany wrote: On Wednesday, 28 August 2019 at 11:34:27 UTC, lili wrote: Hi: Masters who can write a book for Phbos, the dlang doc not friendly to beginner. There are 2 articles which I really like: http://nomad.uk.net/articles/hidden-treasure-in-the-d-standard-library.html http://nomad.uk.net/articles/more-hidden-treasure-in-the-d-standard-library.html Also this book is a good starting point: https://ddili.org/ders/d.en/index.html Are you interested in some specific parts of Phobos? Kind regards Andre Thanks, In'D is great book, not not cover Phobos, I relay need some document for containers, range.
How to learn Phobos，Phbos hard to used for me.
Hi: Masters who can write a book for Phbos, the dlang doc not friendly to beginner.
Re: [Help!] Use two different assembly symbol in D, but they are same address.
On Saturday, 24 August 2019 at 12:55:57 UTC, a11e99z wrote: On Saturday, 24 August 2019 at 12:16:34 UTC, lili wrote: On Saturday, 24 August 2019 at 12:09:19 UTC, a11e99z wrote: On Saturday, 24 August 2019 at 11:53:01 UTC, lili wrote: [...] resb 8 just reserving 8 bytes not initializing it. probably u compare some garbage. sometimes it equals, sometimes not. no? I write wrong, not if (_vga_x == _vga_y) but if (&_vga_x == &_vga_y) try to do next: add funtion in asm that returns real addresses to vga_x,y extern(C) void asmVgas( int** px, int** py) call it int *px, *py; asmVgas( , ); writefln( "%s=%s,%s=%s",px, &_vga_x,py, &_vga_y); and see result I followed your suggest, call asm_fn in d function. it return address not 0 but is a correct address same as the var address show in link map file. when a try define a __shared int xx, the also 0. after linked all variables address is 0 that in .bss segment. do you know why occur this? [global asm_fn] asm_fn: mov rax, p2_table ret
Re: [Help!] Use two different assembly symbol in D, but they are same address.
On Saturday, 24 August 2019 at 12:09:19 UTC, a11e99z wrote: On Saturday, 24 August 2019 at 11:53:01 UTC, lili wrote: [...] resb 8 just reserving 8 bytes not initializing it. probably u compare some garbage. sometimes it equals, sometimes not. no? I write wrong, not if (_vga_x == _vga_y) but if (&_vga_x == &_vga_y)
[Help!] Use two different assembly symbol in D, but they are same address.
Hi:
definition _vga_x and _vga_y symbol in asm, compile use nasm -f
elf64 -o boot.o boot.asm
[section .bss]
...
[global _vga_x]
_vga_x:
resb 8
[global _vga_y]
_vga_y:
resb 8
and nm boot.o show below
...
00107000 B _vga_x
00107008 B _vga_y
and In another D file use this two symbol
extern(C) {
extern __gshared int _vga_x; //definition in boot.asm
extern __gshared int _vga_y; //definition in boot.asm
}
void tt()
{
if (_vga_x == _vga_y)
//where is true, why?
}
but when a run tt so strange things happend that the test is
true.
Is where has a coding mistake.
src https://github.com/lilijreey/OS-D
how to definition a non-const pointer that point a const var.
Hi: In C we can definition const int *ncp_to_cv; or int * const cp_to_ncv; How to do this in D.
How to removes an variable topmost const. like remove_const in C++.
Hi:
I write a template function is below, that need to remove
const topmost if has.
How to do this?
const int i =3;
println(i);
void println(A...)(A a)
{
char[20] numStr = void;
foreach(v ; a) {
if (is(v.type == byte) || is(v.type == ubyte) ||
is(v.type == short) || is(v.type == ushort) ||
is(v.type == int) || is(v.type == uint) ||
is(v.type == long) || is(v.type == ulong)) {
//did not wirte const types ... again.
ulong n = cast(ulong)v;
bool isNeg = false;
if (v < 0) {
isNeg = true;
if (n != 1<<63)
n = -v;
}
int i=0;
while(n !=0 ) {
numStr[i++] = (n%10) + '0';
n/=10;
}
if (isNeg)
putc('-');
while (--i >= 0)
putc(numStr[i]);
} else if (is(v.type == char*) || is(v.type == const
char*)) {
puts(v);
} else if (is(v.type == bool)) {
puts(v ? "true":"false");
} else if (is(v.type == char)) {
putc(v);
} else {
static assert(false);
}
}
}
Re: How to write __traits(isSame, T, int) use another way
On Thursday, 22 August 2019 at 17:01:09 UTC, Adam D. Ruppe wrote:
On Thursday, 22 August 2019 at 16:54:56 UTC, lili wrote:
I think the __traits(isSame, T, int) syntax is too uglily,
Is where an other way rewrite it. like this
isSameType!(T,int)
For types you can (and often should) just use
is(T == int)
the isSame thing is more about comparing aliases rather than
types.
Thanks alot, How to get a variable's type?
void println(A...)(A a)
{
//TODO static if type
foreach(c ; a) {
static if (??(c) == int) //How to get c's type???
}
}
How to write __traits(isSame, T, int) use another way
Hi: I think the __traits(isSame, T, int) syntax is too uglily, Is where an other way rewrite it. like this isSameType!(T,int)
How to set a global var to a user defined section.
Hi:
With gcc we can use _ attribute _((section("name")) var; how
to same in dlang?
What the abstrac final class mean?
Hi: Why need defined an abstract final class? see https://github.com/Rikarin/Trinix/blob/master/Kernel/arch/amd64/gdt.d
How to mark a condition is likeyly or unlikey ？
Hi： In C there has likely unlikely marco used by condition expression。 #define likely(x) __builtin_expect(!!(x), 1) #define unlikely(x) __builtin_expect(!!(x), 0) if (likely(var > 1)) do... How to do this in Dlang？
Where can find the GC impletement source code?
Hi Guys: I look for the GC source code in /usr/include/dmd dir, unfortunately not find.
There is a computer languages benchmark compare site, but no Dlang benchmark. I think they should support D.
A nick site, has a lot of languages, unfortunately no dlang in there. https://benchmarksgame-team.pages.debian.net/benchmarksgame/
Re: What is iota function full name
On Friday, 21 June 2019 at 09:09:33 UTC, aliak wrote: On Friday, 21 June 2019 at 09:01:17 UTC, lili wrote: Hi Guys： What is range.iota function full name That is the full name. Or what do you mean? Found on the internet somewhere: "The function is named after the integer function ⍳ from the programming language APL." I mean is that the what is iota stands for. in dictionary iota means: a tiny or scarcely detectable amount the 9th letter of the Greek alphabet but this function is not that mean.
What is iota function full name
Hi Guys： What is range.iota function full name
What is the difference between extern(C++) extern(D)
Hi Guys; In the dmd source code, has lot of extern (C++), Why need this and what is difference between extern(C++) extern(D), Thanks your answer.
Re: Where can find fix length array memory layout document
On Wednesday, 19 June 2019 at 12:53:05 UTC, Cym13 wrote:
Did you import it properly?
```
void main() {
import core.stdcpp.array;
auto a = array!(int, 4)();
}
```
compiles and runs without issue for me. You'll have to show
your code if you want people to help you there.
Ok, where has some mistake in my code. thanks.
Re: Where can find fix length array memory layout document
On Tuesday, 18 June 2019 at 17:29:49 UTC, Cym13 wrote: On Tuesday, 18 June 2019 at 17:25:42 UTC, Cym13 wrote: On Tuesday, 18 June 2019 at 13:05:03 UTC, lili wrote: On Tuesday, 18 June 2019 at 12:39:45 UTC, Dennis wrote: [...] Thanks a lot, where is a core.stdcpp.array , How to user it? I test but get a error ``` auto aa = array!(int, 4); //error ``` Please don't shorten your code or errors to the point where there's hardly any information left: it's hard to help you if we can't know what you did and what went wrong. Forgot to say that it's probably because you don't actually build an array here, try adding parentheses: ``` auto aa = array!(int, 4)(); ``` array!(int,4)(); compile occurs a error say: no overload matches for array
Re: Why after writeln the binaryHeap become empty?
On Tuesday, 18 June 2019 at 17:25:51 UTC, Johannes Loher wrote: The result of heapify is a BinaryHeap, which is a range. writeln basically prints ranges by iterating over them and printing each element (except for the types which are special cased, such as dynamic arrays etc.). However, ranges are consumed by iterating over them, which explains the behavior because writeln is not special cased for BinaryHeaps. Funnily enough, BinaryHeap does not implement a "save" method, which is the usual way of making ranges copiable, i.e. making them ForwardRanges. In this case I believe save could even simply be an alias to dup. Do you known reason for why Dlang Range are consumed by iterating over them. I this design is strange.
Why after writeln the binaryHeap become empty?
Hi Guys:
see this code
~~~
int[] ar = [1,2,3,4,52,34,22];
auto h = heapify(ar);
assert(h.length() == ar.length);
writeln("h:",h);
assert(h.empty());
~~~
dmd v2.086.0 run all assert passed. Why?
Re: Where can find fix length array memory layout document
On Tuesday, 18 June 2019 at 12:39:45 UTC, Dennis wrote: On Tuesday, 18 June 2019 at 12:26:14 UTC, lili wrote: Hi guys: Is the Dlang fix-length array alloc on stack? when a test writeln([1]).sizeof //16 writeln([2]).sizeof //16 Why, What is the fix-length array memory layout. I'm assuming you mean writeln([1].sizeof). An array literal is a slice of a dynamic array (which is length + pointer, so 2*size_t size). A fixed size array has to be declared as a local / member variable, and then the content is on the stack: ``` int[10] a; writeln(a.sizeof); // 40 writeln(a[].sizeof); // 16 on 64-bit or 8 on 32-bit ``` To get a static array literal, you can use the library function staticArray: ``` import std.array; writeln([1, 2, 3].staticArray.sizeof); // 12 ``` Thanks a lot, where is a core.stdcpp.array , How to user it? I test but get a error ``` auto aa = array!(int, 4); //error ```
Where can find fix length array memory layout document
Hi guys: Is the Dlang fix-length array alloc on stack? when a test writeln([1]).sizeof //16 writeln([2]).sizeof //16 Why, What is the fix-length array memory layout.
Where can find dmd back-end source code.
Hi gues: I clone the dmd source code from github but i can find backend code. there is a backend dir in src but can not find x86 native code generator. and the dmd wiki page just say Back end FileFunction html.c Extracts D source code from .html files but source can't find html.c file.
