Re: Question about: ("1.1").to!int;
On Saturday, 24 October 2020 at 04:04:18 UTC, Виталий Фадеев
wrote:
On Friday, 23 October 2020 at 16:59:06 UTC, matheus wrote:
On Friday, 23 October 2020 at 13:57:41 UTC, Joseph Rushton
Wakeling wrote:
On Wednesday, 21 October 2020 at 22:50:27 UTC, matheus wrote:
Well since the caller is handling a string, shouldn't the
caller verify the content before any conversion?
What if:
"1.1.1".to!int
?
The algorithm will become more complicated?
Will the speed decrease?
I don't get...
Anyway this should fail, look "1.1" is one thing, "1.1.1" is
another thing as "1.a" is another thing.
Like I said before I think the behavior should be the same in
these cases:
(1.1).to!int = 1.
("1.1").to!int = Current is an error and IMO should be 1.
Now for your question:
1.1.1.to!int = Error: found `0.1` when expecting `,`.
"1.1.1".to!int = Should be the same as above.
Matheus.
Re: Question about: ("1.1").to!int;
On Friday, 23 October 2020 at 13:57:41 UTC, Joseph Rushton
Wakeling wrote:
On Wednesday, 21 October 2020 at 22:50:27 UTC, matheus wrote:
Since (1.1).to!int = 1, shouldn't the string value
("1.1").to!int at least try to convert to float/double and
then to int?
The thing is, that's a great way for hard-to-identify bugs to
creep into code. In these cases:
auto a = (1).to!int; // this works
auto b = ("1").to!int; // this works
auto c = (1.1).to!int; // this works and c = 1
... then what the programmer wants is unambiguous. In the
first case it's just converting int => int. In the second,
it's converting from a string that unambiguously represents an
integer value, to an int. And in the third, it's converting
_at programmer request_ from a double to an int (which has a
well-defined behaviour).
However, if ("1.1").to!int were to work, this would be the `to`
function making a judgement call on how to handle something
ambiguous. And while that judgement call may be acceptable for
your current use-case, it won't be for others.
I got it everything you said, but like a said previously:
(1.1).to!int vs ("1.1").to!int
One is a decimal literal while the other is a string
representation of a decimal.
To be honest I think the function is already making a judgment
call when I do (1.1).to!int and returns 1, I really fail to see
the difference when is ("1.1").to!int.
I agree with user1234: "The third case is just like `cast(int)
1.1` it's not _at programmer request_ from my point of view, it's
just that the `to` template has not be more restrictive than the
D `cast` expression. `to` should do at least what a `cast` do and
do more when there's no rule for the two types that are involved."
In particular, if `to` just accepted any string numerical
representation for conversion to int, how could the caller
explicitly _exclude_ non-integer input, if that is their
use-case?
Well since the caller is handling a string, shouldn't the caller
verify the content before any conversion?
Because a string may contain a integer, decimal representation or
neither one.
Finally I don't want to make a fuss of it, I just thought it was
a bit weird but it can be solved easily.
Thanks,
Matheus.
Re: Question about: ("1.1").to!int;
On Friday, 23 October 2020 at 08:09:13 UTC, Виталий Фадеев wrote:
On Wednesday, 21 October 2020 at 22:50:27 UTC, matheus wrote:
Hi,
import std.stdio, std.conv;
void main(string[ ] args) {
auto a = (1).to!int; // this works
auto b = ("1").to!int; // this works
auto c = (1.1).to!int; // this works and c = 1
auto d = ("1.1").to!int; // Doesn't work
}
[...]
1.1 is not int.
"to" works fine.
As solution,... "1.1" should be splitted to lexems: "1", ".",
"1". Then analyze and then converted to int.
Of course 1.1 it's not an integer, but since (1.1).to!int works I
thought that ("1.1").to!int should work too.
Matheus.
Question about: ("1.1").to!int;
Hi,
import std.stdio, std.conv;
void main(string[ ] args) {
auto a = (1).to!int; // this works
auto b = ("1").to!int; // this works
auto c = (1.1).to!int; // this works and c = 1
auto d = ("1.1").to!int; // Doesn't work
}
The forth line gives me:
std.conv.ConvException@/usr/include/dlang/dmd/std/conv.d(1898):
Unexpected '.' when converting from type string to type int
??:? pure @safe int std.conv.toImpl!(int,
immutable(char)[]).toImpl(immutable(char)[]) [0x55de76d9b4d7]
??:? pure @safe int
std.conv.to!(int).to!(immutable(char)[]).to(immutable(char)[])
[0x55de76d99a17]
??:? _Dmain [0x55de76d9986e]
Question:
Since (1.1).to!int = 1, shouldn't the string value ("1.1").to!int
at least try to convert to float/double and then to int?
Because for what I see "to!int" converts from: int,real but in
case of string only when it is a integer representation?
Matheus.
Re: Skipping or Stepping Through an Array?
On Wednesday, 21 October 2020 at 12:06:00 UTC, drug wrote:
There are two other way:
...
// using foreach
foreach (i; 0..a.length)
write(a[i], ", ");
...
Yes you can use foreach, but in this case will not act the way
the OP wanted. In his for loop example the "i" is incremented by
2: "i+=2".
So to perform what OP want with foreach it should be:
foreach (i,j;a){
if(i%2==0){ write(j, ", ");}
}
By the way it's possible to set a "step" value for "foreach"?
Matheus.
Re: Compiler is calling `_memset64` in betterC
On Sunday, 18 October 2020 at 19:24:28 UTC, Ferhat Kurtulmuş wrote: I plan to start a project in reasonable size, I wonder if I should really use betterC... if I encounter a bug like this, will I be stuck at it? The bug report says, it is a dmd specific problem, and LDC, my favorite d compiler, works well (tried it). So the "first party" compiler has a bug while the "third party" one works. That's weird. I would expect the other way around. Matheus.
Re: Working with pointers/adresses
On Thursday, 9 July 2020 at 17:24:33 UTC, matheus wrote:
On Wednesday, 8 July 2020 at 20:33:39 UTC, Paul Backus wrote:
import std.stdio;
void main()
{
int i;
readf("%d\n", i); // read a number
ubyte* p = cast(ubyte*) i; // convert it to a pointer
writeln(*p); // write the data at that address to the
console
}
Note that this program will almost certainly crash if you try
to run it, since modern computers do not allow programs to
read and write arbitrary memory locations.
I wonder if the question was more like intended to display the
value using pointers, ie:
import std.stdio;
void main(){
int i;
readf("%d\n", i);
int *p =
writeln(*p);
}
Because accessing arbitrary memory location seems very weird.
Matheus.
Or maybe he wanted to do this:
import std.stdio;
void main(){
int i;
readf("%d\n", i);
ulong address = cast(ulong)
ubyte* p = cast(ubyte*)address;
writeln(*p);
}
Matheus.
Re: Working with pointers/adresses
On Wednesday, 8 July 2020 at 20:33:39 UTC, Paul Backus wrote:
import std.stdio;
void main()
{
int i;
readf("%d\n", i); // read a number
ubyte* p = cast(ubyte*) i; // convert it to a pointer
writeln(*p); // write the data at that address to the
console
}
Note that this program will almost certainly crash if you try
to run it, since modern computers do not allow programs to read
and write arbitrary memory locations.
I wonder if the question was more like intended to display the
value using pointers, ie:
import std.stdio;
void main(){
int i;
readf("%d\n", i);
int *p =
writeln(*p);
}
Because accessing arbitrary memory location seems very weird.
Matheus.
Re: Privatize a few members to allow messing with them #11353
On Tuesday, 30 June 2020 at 20:01:43 UTC, Stanislav Blinov wrote:
On Tuesday, 30 June 2020 at 19:58:05 UTC, matheus wrote:
+loc.linnum = loc.linnum + incrementLoc;
This works because it was declared:
void linnum(uint rhs) { _linnum = rhs; }
Right?
Almost. Given these definitions:
@safe @nogc pure @property
{
const uint linnum() { return _linnum; }
void linnum(uint rhs) { _linnum = rhs; }
}
This:
loc.linnum = loc.linnum + incrementLoc;
is rewritten as:
loc.linnum(loc.linnum() + incrementLoc);
Alright and thanks again.
Matheus.
Re: Privatize a few members to allow messing with them #11353
On Tuesday, 30 June 2020 at 19:55:56 UTC, matheus wrote:
On Tuesday, 30 June 2020 at 19:46:35 UTC, Stanislav Blinov
...
@safe @nogc pure @property
{
const uint linnum() { return _linnum; }
const uint charnum() { return _charnum; }
void linnum(uint rhs) { _linnum = rhs; }
void charnum(uint rhs) { _charnum = rhs; }
}
...with which the += won't work (at least this variant, as the
getter isn't returning ref).
Oh I see now and thanks for the information.
By the way:
+loc.linnum = loc.linnum + incrementLoc;
This works because it was declared:
void linnum(uint rhs) { _linnum = rhs; }
Right?
Matheus.
Re: Privatize a few members to allow messing with them #11353
On Tuesday, 30 June 2020 at 19:46:35 UTC, Stanislav Blinov wrote:
On Tuesday, 30 June 2020 at 19:42:57 UTC, matheus wrote:
in this case this was more a style thing than anything else
right? Or is there something I'm not able to see?
Before the change, linnum and charnum are public variables, one
can do a += on them. After the change, they become properties
accessing, as the PR says, private variables:
@safe @nogc pure @property
{
const uint linnum() { return _linnum; }
const uint charnum() { return _charnum; }
void linnum(uint rhs) { _linnum = rhs; }
void charnum(uint rhs) { _charnum = rhs; }
}
...with which the += won't work (at least this variant, as the
getter isn't returning ref).
Oh I see now and thanks for the information.
Matheus.
Privatize a few members to allow messing with them #11353
Hi, I was looking the PR in DMD and I found this one: https://github.com/dlang/dmd/pull/11353/ One of the changes was: -loc.linnum += incrementLoc; +loc.linnum = loc.linnum + incrementLoc; I usually do the former and I particularly hate the later, so my question is, in this case this was more a style thing than anything else right? Or is there something I'm not able to see? Thanks, Matheus.
Re: What would be the advantage of using D to port some games?
On Wednesday, 24 June 2020 at 19:46:55 UTC, IGotD- wrote: A previous game implementation in D would be interesting and if you do it you are welcome to write your about experiences here. It's hard to say what features you would take advantage in D as I haven't seen the code in C/C++. However, one thing is clear D would be an easy port because it is so close to C/C++. Every algorithm can be ported directly without any bigger change. If it would Rust you would probably have to rethink some of the data structures and it would be more difficult. Another thing that is clear is that productivity would be high. With today's fast machines and old games you don't have to worry about any GC pauses as there is plenty of time for that. You can basically use the slow "scripting language" features of D. I would expect that D is in the C# ball park in productivity for such task. Thanks for the information. Yes I am thinking about doing it but at the same time I wonder if it's worth (technically speaking) port those games. I'll analyze if there's any part that could take the advantage of some D features that lacks in C/C++. Matheus.
Re: What would be the advantage of using D to port some games?
On Wednesday, 24 June 2020 at 19:14:48 UTC, IGotD- wrote: On Wednesday, 24 June 2020 at 18:53:34 UTC, matheus wrote: What I'd like to know from the experts is: What would be the advantage of using D to port such games? Can you elaborate your question a little bit more. Why would you want to port existing game code to another language to begin with? To see how the game could fit/run in D, like people are porting some of those games to Rust/Go and so on. When you mention "advantage", advantage compared to what? To the original language the game was written. For example taking DOOM (Written in C), in D what would be the features that someone would use to port this game, like using CTFE to generate SIN/COS table would be reasonable? I'm just looking for a roughly idea of this matter. Matheus.
What would be the advantage of using D to port some games?
Hi, I currently use D for small CLI/Batch apps, before that I used to program in C. Despite of using D I usually program like C but with the advantage of: GC, AA, CTFE and a few classes here and there. As we can see there are a lot of old classic games source available like: DOOM, Duke Nukem 3D, Red Alert and most them written originally in C/C++. What I'd like to know from the experts is: What would be the advantage of using D to port such games? Thanks in advance, Matheus.
Re: How to use this forum ?
On Wednesday, 20 May 2020 at 20:49:52 UTC, Vinod K Chandran wrote: Hi all, I have some questions about this forum. 1. How to edit a post ? 2. How to edit a reply ? 3. How to add some code(mostly D code) in posts & replies. 4. How to add an image in posts & replies. 5. Is there a feature to mark my post as "[SOLVED]" ? In few words: This Forum is an interface for mailing lists, you can't do most of these things, I mean not as easy like you do in most Forums (With database to edit content). Personally I prefer this way, because I really hate when people edit their posts, even for good reasons. Matheus.
Re: DConf 2017 Videos
On Saturday, 25 April 2020 at 11:11:07 UTC, Jacob Carlborg wrote: I have previously downloaded the DConf videos. I sent them to Mike for him to upload. Thank you very much for this.
Re: DConf 2017 Videos
On Friday, 24 April 2020 at 21:11:48 UTC, Steven Schveighoffer wrote: ... and whomever controlled the sociomantic youtube account took down all the videos... First of all thanks for replying and... Ouch! After that I hope D Foundation learned the lesson and keep the videos themselves instead of relying in third party next time. I think it's time to have a Wayback Machine version for videos. Thanks.
DConf 2017 Videos
Hi, please could someone tell me where can I find videos from DConf 2017? I pretty sure I watched them on Youtube sometime ago, but I can't find anymore. By the way, I'm looking from one video where someone shows some "C flaws" and how to D as Better C could solve that. I think it was the second talk in this list: https://dconf.org/2017/schedule/ Any idea? Thanks.
Re: Swedish letters fuck up parsing into SQL querry
On Monday, 23 March 2020 at 15:41:50 UTC, Adam D. Ruppe wrote:
On Monday, 23 March 2020 at 15:15:12 UTC, Anders S wrote:
I'm creating a connection to the db and conn.exec(sql)
It depends on the library but it is almost always easier to do
it right than to do it the way you are.
like with my lib it is
db.query("update celldata set name = ?", new_name);
I'm not the OP but I have a question, isn't this passive to SQL
injection too, or your LIB will handle this somehow?
If is the later could you please point the code on GitHub?
Matheus.
Re: How to get child class Type and members from parent class?
On Wednesday, 20 November 2019 at 13:46:07 UTC, Jacob Carlborg
wrote:
On Wednesday, 20 November 2019 at 10:05:11 UTC, zoujiaqing
wrote:
import std.stdio;
class A
{
this(T)(T t)
{
}
void write()
{
T _this = cast(T) this;
writeln(this.v);
}
}
class B : A
{
string v = "hello";
}
void main()
{
auto b = new B;
writeln(b.write()); // print hello
}
You can use a template this parameter [1], like this:
import std.stdio;
class A
{
void write(this T)()
{
T self = cast(T) this;
writeln(self.v);
}
}
class B : A
{
string v = "hello";
}
void main()
{
auto b = new B;
b.write();
}
[1] https://dlang.org/spec/template.html#template_this_parameter
--
/Jacob Carlborg
I'm not the OP but a lurker, and this is new to me, I mean in
your example you're accessing a member "v" which wasn't defined
in the Parent class.
So if someone creates something like this:
class C : A{
string x = "world"; // x instead of v
}
Not the "x" instead of "v", of course it will only get an
compiler error if that function is called in by "C" object.
I think this is a powerful and weird feature at the same time,
because some could write a code like this:
import std.stdio;
class A{
void write(this T)(){
T self = cast(T) this;
writeln(self.v);
}
void write2(this T)(){
T self = cast(T) this;
writeln(self.x);
}
}
class B : A{
string v = "hello";
}
class C : A{
string x = "world";
}
void main(){
auto b = new B;
b.write();
auto c = new C;
c.write2();
}
This is a different way of designing things, do people use this
often?
Matheus.
Re: Help making a game with transparency
Ok, I took a look over my old projects and I found exactly what
you want, by the way it's from 2012.
It uses Derelict 2.0 bindings and will draw a PNG image where you
can move around with cursor keys.
If you want I can send you the whole project (Makefile, DLL's)
and everything else to build it.
Code:
/* 02/10/2012 */
import std.stdio;
import derelict.sdl.sdl;
import derelict.sdl.image;
pragma(lib, "DerelictSDL.lib");
pragma(lib, "DerelictUtil.lib");
pragma(lib, "DerelictSDLImage.lib");
void main(){
// Screen width, height and bit per pixel AKA color
int width = 600, height = 480, bpp = 24;
short xPos, yPos;
// Load Derelict SDL bindings
DerelictSDL.load();
DerelictSDLImage.load();
SDL_Surface* screen;
SDL_Rect rScreen;
// Pointing to an Array of the current key state
Uint8 *keystate = SDL_GetKeyState(null);
// Try initiate SDL
if (SDL_Init(SDL_INIT_VIDEO) < 0){
throw new Exception("Failed: Can not initialize SDL!");
}
screen = SDL_SetVideoMode(width, height, bpp, SDL_ANYFORMAT);//
SDL_HWSURFACE);
IMG_Init(IMG_INIT_PNG);
auto img = IMG_Load("caco.png");
if(img is null){
throw new Exception("Image not found!");
}
writeln(" - w: ",img.w, " - h: ", img.h, " - bpp:",
img.format.BitsPerPixel);
if (screen is null){
throw new Exception("Failed: Can not set video! ");
}
SDL_WM_SetCaption("Simple Example", null);
xPos = cast(short)(width / 2 - 128);
yPos = cast(short)(height / 2 - 128);
// Game loop
while(!keystate[SDLK_ESCAPE]){
SDL_Delay(2); // To not stress CPU
// Fill screen with RED
SDL_FillRect(screen, null, 0xFF);
// Update key state array
SDL_PumpEvents();
// User's control
yPos += keystate[SDLK_DOWN]-keystate[SDLK_UP];
xPos += keystate[SDLK_RIGHT]-keystate[SDLK_LEFT];
// Where to plot the image on the screen
rScreen.x = xPos;
rScreen.y = yPos;
rScreen.w = rScreen.h = 256;
SDL_BlitSurface(img,null,screen,); // Draw Image
SDL_Flip(screen); // Update Screen
}
IMG_Quit();
SDL_FreeSurface(img);
SDL_Quit();
}
Matheus.
Re: Help making a game with transparency
On Friday, 27 September 2019 at 21:16:07 UTC, Murilo wrote: ... Here it is, how do I make the ship have a transparent background? First: Your PNG file has transparency data information right? Second: I was Looking into the drawImage function (Line 854): https://github.com/adamdruppe/arsd/blob/b0d21de148ef0b23ea845be322af5e6931ca4cb6/screen.d And I'd suggest you to try to add the glEnable(GL_ALPHA_TEST); before glBegin(GL_QUADS); In fact you should do this only once, maybe inside the constructor, but just try it there to see if it works. Matheus.
Re: Help making a game with transparency
On Friday, 27 September 2019 at 16:36:14 UTC, Murilo wrote: ...Do you know the arsd library? Yes but I use mostly terminal.d and others. On the other hand I use to code games too using SDL and OpenGL. I know for example in OpenGL you can do: glEnable(GL_ALPHA_TEST); to enable alpha channel and set transparency. Matheus.
Re: Help making a game with transparency
On Friday, 27 September 2019 at 02:54:27 UTC, Murilo wrote: Hi guys, I am making a game but for some reason the sprites do not show with the transparent background that they were supposed to. I'm using the arsd library. Can anyone help me? Sorry this is a bit vague. I suppose you're using engine.d or screen.d directly right? Depending on your setup (OpenGL or Software) transparency will be different. For example take a look at line 733, putpixel function and you'll see that It handle Color differently if it's OpenGL x Software and for the latter it checks if 32bpp or less. Now if it's OpenGL take a look for "Alpha". Matheus.
Re: Private variables accessible from outside class
On Thursday, 8 August 2019 at 15:51:45 UTC, Drobet wrote: ... My question is if this is intended behavior, and if yes, why? This is true if the class is inside the same module: "Private means that only members of the enclosing class can access the member, or members and functions in the same module as the enclosing class. Private members cannot be overridden."[1] Matheus. [1]https://wiki.dlang.org/Access_specifiers_and_visibility
Re: Question about ubyte x overflow, any safe way?
On Monday, 5 August 2019 at 01:41:06 UTC, Ali Çehreli wrote: ... Two examples with foreach and ranges. The 'ubyte.max + 1' expression is int. The compiler casts to ubyte (because we typed ubyte) in the foreach and we cast to ubyte in the range: ... Maybe it was a bad example of my part (Using for), and indeed using foreach would solve that specific issue, but what I'm really looking for if there is a flag or a way to check for overflow when assigning some variable. ubyte u = 260; // Here should be given some warning or throw exception. It's ubyte, but it could be any other data type. Thanks anyway, Matheus.
Re: Question about ubyte x overflow, any safe way?
On Sunday, 4 August 2019 at 18:38:34 UTC, Paul Backus wrote:
...
Use std.experimental.checkedint:
import std.stdio;
import std.experimental.checkedint;
void main()
{
for(Checked!(ubyte, Throw) u = ubyte(250); u < 256; ++u) {
writeln(u.get);
}
}
An exception will be thrown when you attempt to increment u
above 255.
Unfortunately I'm using DMD 2.072 which doesn't support this, but
I'll upgrade soon as I can and will check this out.
Thanks,
Matheus.
Re: Question about ubyte x overflow, any safe way?
On Sunday, 4 August 2019 at 18:15:30 UTC, Max Haughton wrote: What do you want to do? If you just want to count to 255 then use a foreach This was just an example, what I'd like in this code is either: Get an error (exception) when overflow or even an warning (Only if "some" flag was active). If you want to prevent overflow you must either use BigInt or wrap ubyte in a struct that doesn't allow overflow Could you please elaborate about this struct wrapping? Do you mean manually check on change? Matheus.
Question about ubyte x overflow, any safe way?
Hi,
The snippet below will produce an "infinite loop" because
obviously "ubyte u" will overflow after 255:
import std.stdio;
void main(){
ubyte u = 250;
for(;u<256;++u){
writeln(u);
}
}
Question: Is there a way (Flag) to prevent this?
Matheus.
Re: Speed of Random Numbers
On Saturday, 3 August 2019 at 16:35:34 UTC, Giovanni Di Maria
wrote:
For me the "goodness of random" is NOT important.
If that's the case, you could roll your own RNG:
//DMD64 D Compiler 2.072.2
import std.stdio;
import std.datetime;
import std.array, std.random;
void main(){
ubyte x;
auto r = benchmark!(f1,f2)(10_000);
writeln(r[0]);
writeln(r[1]);
}
int f1(){
static s = 10; // Seed
s = (214013*s+2531011); // [1]
s = (s>>16)&0x7FFF;
auto y=(s&7)+1;
//writeln(y);
return y;
}
int f2(){
byte c;
c=uniform!ubyte() % 8 +1;
//writeln(c);
return c;
}
/*
[1]
https://software.intel.com/en-us/articles/fast-random-number-generator-on-the-intel-pentiumr-4-processor/
*/
/*
OUTPUT:
TickDuration(65263) <-f1
TickDuration(635167) <-f2
*/
Matheus.
Re: Help me decide D or C
On Thursday, 1 August 2019 at 09:43:20 UTC, Kagamin wrote: On Wednesday, 31 July 2019 at 22:30:52 UTC, Alexandre wrote: 1) Improve as a programmer 2) Have fun doing programs Thats it basically. I am planning to study all "free" time I have. I am doing basically this since last year. Try Basic. It has builtin graphics, seeing you program draw is quite fascinating. In that case I'd recommend EvalDraw: http://advsys.net/ken/download.htm with a C-like syntax with draw things while you type. Description: "A complete programming environment with built-in compiler, text editor, and functions to allow for quick prototyping. With Evaldraw, you can make graphs in any dimension (1D, 2D, 3D), animations, custom musical instruments, voxel models, and general purpose applications. I've included a lot of examples, so even if you're not a programmer, you can look at the demos" It was written by Ken Silverman (Creator of Build Engine - Duke Nukem 3D). Matheus.
Re: Help me decide D or C
On Wednesday, 31 July 2019 at 18:38:02 UTC, Alexandre wrote: ... Should I go for C and then when I become a better programmer change to D? Should I start with D right now? ... I think it depend your intent, but right now for a beginner between C and D I would go with C, because as you noted there are plenty of resources for C, C++, Python etc. In some colleges where I live, 10+ years ago they used to start CS class with C and then C++ or Java, now they start with Python and then C and so on. Python was "more" friendly for beginners to understand variable/algorithm, and after that they would go with data types, pointers... more easily. Good luck, Matheus.
Re: Blog Post #0050: MVC III - ComboBoxText, Add & Remove
On Friday, 5 July 2019 at 09:34:08 UTC, Ron Tarrant wrote: Today is a bit of a milestone for the blog as the 50th regular post goes up. Also, the facelift is coming along nicely, the next phase of which should be ready to push by July 9th. And today's topic continues with the MVC series by demonstrating how to add and remove items from a ComboBoxText widget. You can read it here: https://gtkdcoding.com/2019/07/05/0050-mvc-iii-comboboxtext-add-remove.html Maybe you should post this on the Announce group? And on Reddit too. Matheus.
Re: create and initialise array
On Thursday, 20 June 2019 at 01:06:09 UTC, Alex wrote:
Is there a way of creating and initialising a dynamic array ?
for example I am doing this:
auto arr = new float[];
arr[] = 0.0f;
Profiling indicates that the compiler (gdc) is spending
significant time memsetting the whole array to something (nan
?) before I immediately memset it to 0.0f.
It would be good if there was a way of either void initialing
it so that the first memset is avoided or a way of replacing
the init value with a different one.
Thanks,
Alex
What about:
//DMD64 D Compiler 2.072.2
import std.stdio;
import std.array;
void main(){
auto s = uninitializedArray!(float[])(100);
s[] = 0.0f;
writeln(s[0]);
}
Matheus.
Re: Reuse/reset dynamic rectangular array?
On Saturday, 25 May 2019 at 14:28:24 UTC, Robert M. Münch wrote:
How can I reset a rectangualr array without having to loop
through it?
int[][] myRectData = new int[][](10,10);
myRectData.length = 0;
myRectData[].length = 0;
myRectData[][].length = 0;
They all give: slice expression .. is not a modifiable lvalue.
This works form me:
//DMD64 D Compiler 2.072.2
import std.stdio;
void main()
{
auto arr = new int[][](10,10);
writeln(arr.length);
arr.length=0;
writeln(arr.length);
}
output:
10
0
Matheus.
Re: Performance of tables slower than built in?
On Wednesday, 22 May 2019 at 00:55:37 UTC, Adam D. Ruppe wrote: On Wednesday, 22 May 2019 at 00:22:09 UTC, JS wrote: I am trying to create some fast sin, sinc, and exponential routines to speed up some code by using tables... but it seems it's slower than the function itself?!? There's intrinsic cpu instructions for some of those that can do the math faster than waiting on memory access. It is quite likely calculating it is actually faster. Even carefully written and optimized tables tend to just have a very small win relative to the cpu nowadays. Exactly, and by the way this is old feature already. I remember like long time ago when I was studying/writing some games and I decided to test pre-computed arrays (LUT) for SIN/COS vs functions, and the later would beat the arrays pretty easily. And by the way when porting old games, sometimes you usually (If not change the game logic too much), get rid of the LUT and use functions directly. Matheus.
Re: Struct destructor
On Saturday, 2 March 2019 at 11:32:53 UTC, JN wrote:
...
Is this proper behavior? I'd imagine that when doing
foos.remove("bar"), Foo goes out of scope and should be
immediately cleaned up rather than at the end of the scope? Or
am I misunderstanding how should RAII work?
https://dlang.org/spec/struct.html#struct-destructor
"Destructors are called when an object goes out of scope. Their
purpose is to free up resources owned by the struct object."
Example:
import std.stdio;
struct S
{
~this()
{
import std.stdio;
writeln("S is being destructed");
}
}
void main(){
{
S s = S();
scope (exit)
{
writeln("Exiting scope");
}
}
writeln("Ending program.");
}
Output:
Exiting scope
S is being destructed
Ending program.
Matheus.
Re: How to cast arrays?
On Saturday, 2 March 2019 at 02:14:01 UTC, Murilo wrote:
How do I cast a ubyte[] into uint[]? It keeps raising an error,
I have read the documentation saying there are restrictions for
that concerning the length of the arrays.
By the way here is how:
void foo(){
ubyte[] x = [1,2];
auto y = (cast(int*) )[0..2];
writeln(y);
}
Matheus.
Re: How to cast arrays?
On Saturday, 2 March 2019 at 02:14:01 UTC, Murilo wrote: How do I cast a ubyte[] into uint[]? It keeps raising an error, I have read the documentation saying there are restrictions for that concerning the length of the arrays. https://dlang.org/spec/expression.html#cast_expressions "Casting a dynamic array to another dynamic array is done only if the array lengths multiplied by the element sizes match. The cast is done as a type paint, with the array length adjusted to match any change in element size. If there's not a match, a runtime error is generated." Matheus.
Re: Modulo that 'wraps' the number?
On Monday, 21 January 2019 at 18:39:27 UTC, Steven Schveighoffer
wrote:
Not a Python user, just hoping to help answer questions :)
Yes I know in fact I'm not the OP but from what I understood from
his post, he want to replicate, but I may be wrong.
If it's the case, this code may help him:
//DMD64 D Compiler 2.072.2
import std.stdio;
import std.math;
int mod(int i,int j){
if(abs(j)==abs(i)||!j||!i||abs(j)==1){return 0;};
auto m = (i%j);
return (!m||sgn(i)==sgn(j))?(m):(m+j);
}
void main(){
int j,i;
for(j=1;j<9;++j){
for(i=1;i<9;++i){
writeln(-i, " % ", +j, " = ", (-i).mod(+j));
writeln(+i, " % ", -j, " = ", (+i).mod(-j));
}
}
}
At least the code above gave me the same results as the Python
version.
Matheus.
Re: Modulo that 'wraps' the number?
On Monday, 21 January 2019 at 15:01:27 UTC, Steven Schveighoffer wrote: Probably, this optimizes into better code, but maybe the optimizer already does this with the expression above: auto tmp = n % 3; if(tmp < 0) tmp += 3; It's just not a nice single expression. -Steve I don't think you can do this, imagine this case: auto tmp = -1 % -3; // Note divisor in negative too. tmp will be "-1" which already matches the Python way, so you can't add divisor anymore. Matheus.
Re: Is there a nice syntax to achieve optional named parameters?
On Thursday, 17 January 2019 at 16:55:33 UTC, SrMordred wrote:
Yes, but there is a mistake there:
alias is part of the template:
foo(alias x)(){} //note extra parens
than u call like an template:
foo!"a"; //equivalent = foo!("a")();
foo!1;
I see now and thanks.
Matheus.
Re: Is there a nice syntax to achieve optional named parameters?
On Thursday, 17 January 2019 at 01:43:42 UTC, SrMordred wrote:
Let me throw this idea here:
...
I usually do this too, I like to use struct and then in another
language I use reflection do optimize binding.
Anyway I understood all your code, except for this "alias code"
auto NewWindow( alias code )()
{
mixin("Config config = {"~code~"};");
return Window(config);
}
Looking on specs: https://dlang.org/spec/declaration.html#alias
"AliasDeclarations create a symbol that is an alias for another
type, and can be used anywhere that other type may appear."
So with your example imagine this:
foo(alias x){}
foo("a");
foo(1);
'x' will be string one time and integer another? Or there is
something that I'm missing.
Matheus.
