static array of pointers to dynamic arrays of ints problem...
Surely a stupid mistake on my part, but why is the first array
repeated?
import std.stdio;
void main()
{
int[]*[2] a; // a static arrray holding pointers to dynamic
arrays
static int unique = 0;
foreach(i, elem; a)
{
int[] temp = new int[](5);
foreach(ref element; temp)
{
element = unique;
unique++;
}
writeln("temp = ", temp);
a[i] =
}
foreach(i, elem; a)
{
writeln(a[i].length);
writeln("[", i, "][]", *a[i]);
}
}
temp = [0, 1, 2, 3, 4]
temp = [5, 6, 7, 8, 9]
5
[0][][5, 6, 7, 8, 9]
5
[1][][5, 6, 7, 8, 9]
why use string for this example of appender?
I think I got a handle on D's static and dynamic arrays, till I
come to std.array and see all the shiny new tools. I can
understand all the replace.. functions, but the appender function
gave me pause. The documentation says appender "Returns a new
Appender or RefAppender initialized with a given array."
My first thought that doesn't D's built in arrays already allow
appending? (at least for dynamic arrays) And the example shows
the use of appender with string. Isn't string an immutable array
or characters? Wouldn't this be the last data type you would
want to be appending to? Another thing that had me wondering is
the use of put() down below; doesn't the append syntax (~=) give
you the same exact functionality; so why bother?
void main()
{
import std.array;
import std.stdio: write, writeln, writef, writefln;
auto w = appender!string;
// pre-allocate space (this avoids costly reallocations)
w.reserve(10);
assert(w.capacity >= 10);
w.put('a'); // single elements
w.put("bc"); // multiple elements
// use the append syntax
w ~= 'd';
w ~= "ef";
writeln(w.data); // "abcdef"
Re: Proposed Phobos equivalent of wcswidth()
On Monday, 15 January 2018 at 13:34:09 UTC, Jack Stouffer wrote: On Saturday, 13 January 2018 at 17:26:52 UTC, H. S. Teoh wrote: ... Thanks for taking the time to do this. And now the obligatory bikeshed: what should the Phobos equivalent of wcswidth be called? std.utf.displayWidth std.utf.bikeshed Never heard that phrase before. Nice one :)
Re: Infuriating DUB/DMD build bug.
On Friday, 6 October 2017 at 23:02:56 UTC, Laeeth Isharc wrote: On Thursday, 5 October 2017 at 21:48:20 UTC, WhatMeWorry wrote: I've got a github project and using DUB with DMD and I keep running into this problem. I've tried deleting the entire ...\AppData\Roaming\dub\packages folder, but the problem repeats the very next build attempt. [...] See my post in learn on dmd path. The dmd path code was written in 1987 and could do with an update to process longer windows paths properly. We are working on this and I guess a chance a pull request on Monday but it depends on what else comes up. In any case it's a trivial fix. Presuming I am right about it being a path length problem. I did! But i didn't say anything because i wasn't sure if they were related. I'm pretty sure it is path related because the exact same dub.sdl files work fine on Linux and MacOS. (It's a cross platform project) Glad it is a trivial fix. Curious what it involves. Let me know if I can help out in any way. Mike Parker was kind enough to show me a manual dub local workaround for this issue. But I'll hold off now and see if your change does the fix. If it does, it will be the best timed bug fix ever :)
Real beginner traits question
This is taken exactly from the traits documentation. 25 Traits 25.21 identifier Takes one argument, a symbol. Returns the identifier for that symbol as a string literal. There are no examples. My naive brain keeps thinking that a symbol and an identifier are the same things. Can someone give me good definitions of "symbol" and "identifier". And maybe an example if it is not too much trouble.
Re: What's the best D programming book
On Friday, 25 August 2017 at 21:08:59 UTC, Macdonal wrote: What is the best D-Programming Book? In my opinion, if you are a beginner programmer I'd go with Ali's. If intermediate, I would suggest Learning D by Mike Parker. And if you want some cool idioms and advanced techniques, I'd go with Adam Ruppe's book. Hope the authors agree with my assessment :) They are all good in their own way.
Re: Mixed up over mixins.
On Sunday, 20 August 2017 at 22:50:40 UTC, Johnson Jones wrote: On Sunday, 20 August 2017 at 19:27:43 UTC, WhatMeWorry wrote: [...] It's not difficult, it's just new. It's not that you are a poor programmer, but you simply have not learned how to think about mixins correctly. Stop whining about it and focus that energy on working with them. [...] Thank you. You have rejuvenated my quest for mixin mastery :)
Re: Mixed up over mixins.
On Sunday, 20 August 2017 at 19:41:14 UTC, Ali Çehreli wrote:
On 08/20/2017 12:27 PM, WhatMeWorry wrote:
> // Mixins are for mixing in generated code into the
source code.
> // The mixed in code may be generated as a template
instance
> // or a string.
Yes, it means that the string must be legal D code.
> mixin(`writeln(` ~ `Hello` ~ `);` );
Yes, that's a D string but the string itself is not legal D
code because it would be mixing in the following:
writeln(Hello);
The problem is, there is no Hello defined in the program.
You need to make sure that Hello is a string itself:
writeln("Hello");
So, you need to use the following mixin:
mixin(`writeln(` ~ `"Hello"` ~ `);` );
Ali
Of course, why didn't I "see" that before. I should have slept on
it and tried again with fresh eyes. I'm keeping a "beginners
journal" on code generation. Maybe write a 101 introduction with
lots of samples and exercises.
Thanks. Don't know if you noticed, but i used some code from your
book. Hope you take that as a complement.
real simple delegate question.
Can someone explain what is the difference between the two?
Thanks.
module gates;
import std.stdio;
import std.random;
alias Calculator = int delegate(int);
Calculator makeCalculator()
{
static int context = 0;
int randy = uniform(1, 7);
context++;
writeln("context = ", context);
writeln("randy = ", randy);
return value => context + randy + value;
}
void main()
{
for (int i = 0; i < 3; i++)
{
auto calculator = makeCalculator();
writeln("The result of the calculation: ", calculator(0));
}
}
returns:
context = 1
randy = 5
The result of the calculation: 6
context = 2
randy = 2
The result of the calculation: 4
context = 3
randy = 6
The result of the calculation: 9
while the following
void main()
{
auto calculator = makeCalculator(); // thought just one
would work
for (int i = 0; i < 3; i++)
{
writeln("The result of the calculation: ", calculator(0));
}
}
returns:
The result of the calculation: 3
The result of the calculation: 3
The result of the calculation: 3
Re: I'm the new package maintainer for D on ArchLinux
On Wednesday, 9 August 2017 at 20:50:36 UTC, Stefan Koch wrote: On Wednesday, 9 August 2017 at 20:42:48 UTC, Wild wrote: I hope I can maintain ArchLinux as a great environment to use D. You are not only the new package mainainer but also my new Hero :) +10
Real naive template question
module block_template;
void main()
{
template BluePrint(T, U)
{
T integer;
U floatingPoint;
}
BluePrint!(int, float);
}
// DMD returns
// template.d(13): Error: BluePrint!(int, float) has no effect
// I was expecting something like the following to be created
after compilation:
module block_template;
void main()
{
{
int integer;
float floatingPoint;
}
}
I realize this is a corner case, but shouldn't the
BluePrint!(int, float); statement blindly create a block of code?
I feel the dynamic array .sizeof property is kind of a bait and switch
Static Arrays have property .sizeof which returns the array length multiplied by the number of bytes per array element. Dynamic Arrays have property .sizeof which returns the size of the dynamic array reference, which is 8 in 32-bit builds and 16 on 64-bit builds. Why not have dynamic arrays with a .sizeof identical to static arrays and say another property called .sizeref which handles the 32 or 64 bit references. Maybe Phobos has something that I'm not aware of? I've hand rolled a function which is working for me currently, but with my coding ability, I'd feel much safer with something official :) It just seems like something this basic regarding dynamic arrays should just be built-in.
Re: Is it possible to generate a pool of random D or D inline assembler programs, run them safely?
On Tuesday, 18 July 2017 at 17:35:17 UTC, Enjoys Math wrote: The purpose of it is to make a real-time, short-lived function predictor. I'm genuinely curious. What is a function predictor used for?
Why doesn't this work...Struct std.regex.Captures
I was playing around with regex
import std.regex;
import std.stdio;
void main()
{
string[] fileNames = [ "011_bad.txt", "01_01_pass",
"90_pass", "_bad" ];
auto reg = regex(r"^\d{2}_");
foreach (name; fileNames)
{
auto c = matchFirst(name, reg);
//writeln(c.hit); // Slice of matched portion of input.
if (c.empty)
writeln(name, " is not the form we are looking for");
else
writeln(name, " is a winner");
}
}
All is good:
011_bad.txt is not the form we are looking for
01_01_pass is a winner
90_pass is a winner
_bad is not the form we are looking for
but then I uncommented the writeln(c.hit); above and all hell
breaks loose:
core.exception.AssertError@/usr/include/dmd/phobos/std/regex/package.d(559):
Assertion failure
??:? _d_assertp [0x8124936]
??:? pure nothrow @property @nogc @trusted immutable(char)[]
std.regex.Captures!(immutable(char)[], uint).Captures.hit()
[0x81190d6]
??:? _Dmain [0x80ff351]
??:?
_D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZ9__lambda1MFNlZv
[0x8125bbe]
??:? scope void rt.dmain2._d_run_main(int, char**, extern (C) int
function(char[][])*).tryExec(scope void delegate()) [0x8125b10]
??:? scope void rt.dmain2._d_run_main(int, char**, extern (C) int
function(char[][])*).runAll() [0x8125b7e]
??:? scope void rt.dmain2._d_run_main(int, char**, extern (C) int
function(char[][])*).tryExec(scope void delegate()) [0x8125b10]
??:? _d_run_main [0x8125aa8]
??:? main [0x8122ff3]
??:? __libc_start_main [0xb74dc275]
I got inspiration from the following "live" code at at
.../captures.html. I inserted a writeln(c.hit) and here it worked!
import std.range.primitives : popFrontN;
auto c = matchFirst("@abc#", regex(`(\w)(\w)(\w)`));
assert(c.pre == "@"); // Part of input preceding match
assert(c.post == "#"); // Immediately after match
assert(c.hit == c[0] && c.hit == "abc"); // The whole match
writeln("My Addition ",c.hit);
writeln(c[2]); // "b"
writeln(c.front); // "abc"
c.popFront();
writeln(c.front); // "a"
writeln(c.back); // "c"
c.popBack();
writeln(c.back); // "b"
and it worked fine:
My Addition abc
b
abc
a
c
b
What gives? Thanks.
First time user of LDC and getting newbie problems.
Just trying to compile a "Hello World" using dub and ldc2. The 32 bit works fine: generic@generic-ThinkPad-T61:~/Desktop/test$ dub run --compiler=ldc2 --arch=x86 Performing "debug" build using ldc2 for x86. test ~master: target for configuration "application" is up to date. To force a rebuild of up-to-date targets, run again with --force. Running ./test hello there But all hell breaks out when I try a 64 bit build. I've got a 64 bit cpu and 64 bit Xubuntu so I thought, if I was going to get errors, it would be the previous case. generic@generic-ThinkPad-T61:~/Desktop/test$ dub run --compiler=ldc2 --arch=x86_64 Performing "debug" build using ldc2 for x86_64. test ~master: building configuration "application"... /usr/bin/ld: skipping incompatible /usr/lib/libphobos2-ldc.so when searching for -lphobos2-ldc /usr/bin/ld: skipping incompatible /usr/lib/libphobos2-ldc.a when searching for -lphobos2-ldc /usr/bin/ld: skipping incompatible /usr/lib/gcc/i686-linux-gnu/6/../../../libphobos2-ldc.so when searching for -lphobos2-ldc /usr/bin/ld: skipping incompatible /usr/lib/gcc/i686-linux-gnu/6/../../../libphobos2-ldc.a when searching for -lphobos2-ldc /usr/bin/ld: skipping incompatible //usr/lib/libphobos2-ldc.so when searching for -lphobos2-ldc /usr/bin/ld: skipping incompatible //usr/lib/libphobos2-ldc.a when searching for -lphobos2-ldc /usr/bin/ld: cannot find -lphobos2-ldc /usr/bin/ld: skipping incompatible /usr/lib/libdruntime-ldc.so when searching for -ldruntime-ldc /usr/bin/ld: skipping incompatible /usr/lib/libdruntime-ldc.a when searching for -ldruntime-ldc /usr/bin/ld: skipping incompatible /usr/lib/gcc/i686-linux-gnu/6/../../../libdruntime-ldc.so when searching for -ldruntime-ldc /usr/bin/ld: skipping incompatible /usr/lib/gcc/i686-linux-gnu/6/../../../libdruntime-ldc.a when searching for -ldruntime-ldc /usr/bin/ld: skipping incompatible //usr/lib/libdruntime-ldc.so when searching for -ldruntime-ldc /usr/bin/ld: skipping incompatible //usr/lib/libdruntime-ldc.a when searching for -ldruntime-ldc /usr/bin/ld: cannot find -ldruntime-ldc collect2: error: ld returned 1 exit status Error: /usr/bin/gcc failed with status: 1
Re: DCOnf 2017 videos online
On Sunday, 7 May 2017 at 18:11:47 UTC, Patrick Schluter wrote: It looks like the good people of Sociomantic have already posted videos of the Dconf2017 on youtube. https://www.youtube.com/channel/UC54uUlXuGhigMsdaNtP6THQ Enjoy. Wow. That was quick!
real simple manifest constant question probably regret asking...
One of my D books says: "an enum declared without any braces is called a manifest constant." The example shows, enum string author = "Mike Parker"; Is this equivalent to const string author = "Mike Parker"; or immutable string author = "Mike Parker"; I guess what I'm asking is does enum give you some advantages over say non-enum constants? Thanks.
Re: simple static if / traits question...
On Wednesday, 22 February 2017 at 22:37:25 UTC, Profile Anaysis wrote: On Wednesday, 22 February 2017 at 21:27:47 UTC, WhatMeWorry wrote: I'm doing conditional compilation using static ifs like so: enum bool audio = true; // if audio flag is present and set to true, add to code build static if ( (__traits(compiles, audio)) && audio) playSound(soundSys, BLEEP ); This works, but I thought there might be a simpler way. For instance, after perusing std.traits, I thought I would find something like isPresent(audio) or isSymbol(audio) templates. Or am I being obtuse here? Thanks. You do realize that audio is a compile time constant? This means that in the binary, everything that depends on it is evaluated(as it can be, since it is known). This means that whatever app you are using will not be able to be able to "adapt" to the system changes. In this case, if the system has audio there is no way for the binary to use it because you compiled it out(if audio = false). In such a case you do not want to use a static or compile time variable unless you plan on creating multiple binaries. If your example above was just for demo then yes, you can do that but compiles is not what you want. Compiles only checks if the statement that follows is compilable as valid D code and it doesn't have anything to do with the value of the variables. Definitely overthought this one big time. But there is so much meta goodness in std.traits that I felt compelled to use "compiles" :) There are a few options: 1. static if(audio) 2. version(audio) 3. if (audio) It looks like you are trying to create the version(audio) semantic(if exists then use, else don't). Ultimately, though, if you are trying to make a binary that can either use audio or not depending on where it is ran, you'll have to stick to using actual run time variables and probably be a bit more organized about it. option 1 is the one I was shooting for. does the static if (audio) just check for the existence of audio, or does it also check to see if audio is true as well? I've got a game tutorial with 15 sequential projects. Each project introduces a new concept by building on the previous project code. But I soon had so much code duplication that I decided to use common modules/functions. The specific code could be injected via flags in the apps.d Hence my original question.
Re: Array start index
On Saturday, 1 August 2015 at 09:35:53 UTC, DLearner wrote: Does the D language set in stone that the first element of an array _has_ to be index zero? Wouldn't starting array elements at one avoid the common 'off-by-one' logic error, it does seem more natural to begin a count at 1. Actually, maybe even better to allow array definitions of form int foo[x:y]; (y >= x) creating integer variables foo[x], foo[x+1],...,foo[y]. I think the (very old) IBM PL/I language was like this. There is a good metaphor in multi-story buildings. Americans number the first or ground floor of a high rise as floor #1. In the UK, their first floor is what Americans would call the 2nd floor. But then how can you trust a group of people who drive on the wrong side of the road :)
Re: Should I brush up on my C before plunging fully into D?
On Saturday, 15 October 2016 at 01:46:52 UTC, Chris Nelson wrote: I'm mainly a scripting language, .NET, and SQL programmer. I've been looking for a good programming language for Linux/BSD other than Python. I've surveyed the options and D appears to be a sane modern choice for me. (Thanks Ali Çehreli and others!) The only hitch is that many of the projects and libraries I'm interested in using or maybe porting are mainly C based. (My overall C-fu is weak...) Should I review a good C book or tutorial before jumping in to fully learning D? Or should I just eschew any C exposure until I master D? (As a side note, many of the C libraries I'm interested in seem to be confusing messes of header files and "organic" code. But who am I to judge?) I would jump right into D and then veer off into C on a need to know basis. This link might be of interest: https://dlang.org/ctod.html Also, are you aware of the libraries at the DUB registry? And finally, Chapter 9 of Mike Parker's "Learning D" has lots of info on libraries.
Re: Examples of dub use needed
On Thursday, 23 June 2016 at 07:46:41 UTC, Mike Parker wrote: FWIW, this thread has inspired me to begin work on a project I've titled 'The DUB Handbook'. I've been meaning to write some tutorials about DUB (among other things) for learningd.org, but I think a detailed guide would be a more worthwhile project to pursue. My intention with the text is to provide a detailed description of every dub command and configuration directive, along with examples of how to use them in both JSON and SDLang formats. I've spent an hour getting it set up today (I'm using gitbook) and expect to be working on it over the next several weeks. When it's ready for feedback, I'll make it publicly available and announce it here in the forums. I plan to release it under a CC license. I've been trying to get my head around DUB for a long time. And that is even after buying D Web Development and your Learning D. I would be very interested in providing feedback. I believe it would be very helpful to provide comprehensive "walk throughs" of the most useful and important scenarios. Include windows and Linux since their path layouts differ. Maybe even seed DUB's D Package Registry with a little tutorial package that could be used them. And also throw in some definitions: what is actually meant by "cache", local, dependencies (is this imported source files or libraries needed during linking, or something else) For instance, I installed DUB and some packages on a laptop (running Linux) about a week ago and then left it alone. I'm now back in a terminal and it's like I've completely forgotten everything: I see the directories under ~/.dub but I can't seem to get dub list, dub fetch, or dub run to work? Anyway, sorry to ramble. Thank you for Handbook.
