Re: C Style char**
On Monday, 13 May 2019 at 09:56:19 UTC, evilrat wrote:
On Monday, 13 May 2019 at 09:24:34 UTC, Doug Clayton wrote:
[...]
You don't need to cast it, arrays have .ptr property to get
pointer to first element, and in @safe you just [0]
instead, or so I think.
If you are using static/literal arrays and know what you are
doing this will work.
Otherwise it safer to just use regular string[] array and use
something like that
const(char*)* toCStringList(string[] arr)
{
import std.string; // toStringz() - adds null
terminator, allocates using GC if necessary
import std.array; // array() - eagerly converts range
to array, allocates using GC
import std.algorithm; // map() - apply function to range
return arr
.map!(toStringz)
.array();
}
Thanks so much! That's much more elegant than what I was thinking
I would have to use.
C Style char**
Hi All, First time poster :) I'm working on getting a binding to Vulkan working properly in D, but I've run into a roadblock. The good news is that the binding seems to work fine, but I'm having an issue getting a parameter that needs an input of a const(char*)* to receive all of the members of the array. It only will receive the first member. I've looked through the documentation, but I haven't seen a clear way to cast a char*[] to a char** without it losing the rest of the members. Can anyone help?
Re: Code Reviewer
On Wednesday, 12 August 2015 at 13:14:04 UTC, sigod wrote: On Tuesday, 11 August 2015 at 22:50:52 UTC, Clayton wrote: Hello everyone, Am looking for someone who could help review my code . As an entry exercise to D am converting 3 C implementations of popular pattern matching algorithms. The idea is to have 6 final implementations ( 3 compile-time and 3 runtime) . I think am basically done with the coding, but being a beginner myself, I feel I need some do some critics so I can improve (especially on the compiletime ones). I could have uploaded direct but I think the code may be way too long. Help will be dearly appreciated. Use this site: http://codereview.stackexchange.com/ Thanks sigod, I have also put the compiletime code here : http://dpaste.dzfl.pl/f0bec44f859e
Re: Code Reviewer
On Wednesday, 12 August 2015 at 12:14:20 UTC, Rikki Cattermole wrote: On 13/08/2015 12:09 a.m., Clayton wrote: On Wednesday, 12 August 2015 at 02:49:59 UTC, Rikki Cattermole wrote: On 12/08/2015 10:50 a.m., Clayton wrote: [...] Upload to e.g. Github/gist/pastebin. Hi Rikki, can I have your email so I add you to my repository on BitBucket? No need, as long as it is not propriety code feel free to post the links :) That way anybody who is willing to comment can. Thanks , I have put the compiletime code here : http://dpaste.dzfl.pl/f0bec44f859e
Re: Code Reviewer
On Wednesday, 12 August 2015 at 02:49:59 UTC, Rikki Cattermole wrote: On 12/08/2015 10:50 a.m., Clayton wrote: Hello everyone, Am looking for someone who could help review my code . As an entry exercise to D am converting 3 C implementations of popular pattern matching algorithms. The idea is to have 6 final implementations ( 3 compile-time and 3 runtime) . I think am basically done with the coding, but being a beginner myself, I feel I need some do some critics so I can improve (especially on the compiletime ones). I could have uploaded direct but I think the code may be way too long. Help will be dearly appreciated. Upload to e.g. Github/gist/pastebin. Hi Rikki, can I have your email so I add you to my repository on BitBucket?
Code Reviewer
Hello everyone, Am looking for someone who could help review my code . As an entry exercise to D am converting 3 C implementations of popular pattern matching algorithms. The idea is to have 6 final implementations ( 3 compile-time and 3 runtime) . I think am basically done with the coding, but being a beginner myself, I feel I need some do some critics so I can improve (especially on the compiletime ones). I could have uploaded direct but I think the code may be way too long. Help will be dearly appreciated.
Re: Measuring Execution time
On Wednesday, 22 July 2015 at 09:32:15 UTC, John Colvin wrote: On Wednesday, 22 July 2015 at 09:23:36 UTC, Clayton wrote: [...] The normal way of doing this would be using std.datetime.StopWatch: StopWatch sw; sw.start(); algorithm(); long exec_ms = sw.peek().msecs; Am wondering how possible is to restrict that all algorithms get run on a specific core( e.g. CPU 0 ) since I wanted my test run on the same environment.
Re: Measuring Execution time
On Wednesday, 22 July 2015 at 09:32:15 UTC, John Colvin wrote: On Wednesday, 22 July 2015 at 09:23:36 UTC, Clayton wrote: [...] The normal way of doing this would be using std.datetime.StopWatch: StopWatch sw; sw.start(); algorithm(); long exec_ms = sw.peek().msecs; Much appreciated, that works well John . Learning goes on... thanks again
Measuring Execution time
How does one represent Duration in only Micro-seconds, or
milliseconds. Trying to measure the execution time of an
algorithm and I get 4 ms, 619 μs, and 8 hnsecs , I want to sum
all these and get total hnsecs or μs .
I would also appreciate advise on whether this is the best way
to measure the execution time of an algorithm.
import std.datetime;
import std.stdio;
void algorithm( ){
writeln(Hello!);
}
void main(){
auto stattime = Clock.currTime();
algorithm( );
endttime = Clock.currTime();
auto duration = endttime - stattime;
writeln(Hello Duration == , duration);
}
monitoring variable evaluation time
What could be the best-tool for monitoring the evaluation time of a variable . What I usually do is run the command :- - dmd -J. program.d Then I inspect the program.o file using vi for presence of compile-time constants and enums. I am wondering if this is the right way to do this. Am a bit skeptical about this as am working on pushing everything that the compiler can do to the compiler for faster run-time.
Re: monitoring variable evaluation time
On Monday, 20 July 2015 at 09:29:26 UTC, anonymous wrote: On Monday, 20 July 2015 at 08:53:52 UTC, Clayton wrote: [...] You mean you want to know if some value is pre-computed during compilation? [...] Thankyou a lot for the suggestion. Am noting as I learn the language.
Re: monitoring variable evaluation time
On Monday, 20 July 2015 at 10:11:10 UTC, Marc Schütz wrote: On Monday, 20 July 2015 at 08:53:52 UTC, Clayton wrote: [...] I'm not sure that's what you want to know, but... The evaluation time of expressions is completely deterministic. Global (module level) or static variables, default values for struct/class members, template arguments, as well as enums, are evaluated at compile-time and thus their construction has no runtime costs. [...] Thankyou a lot for the suggestion. Am noting as I learn the language.
static-if cant compile
Pardon me for trivial question, Am new to D.
Why would a statement as below fail to compile. The plan is to do
some computation at compile-time hence considering the static-if
statement which fails to compile. The regular if-statement
compiles but is not useful since it is a runtime construct.
The error message I get is : Error: variable i cannot be read at
compile time
foreach( i; 0..size-1){
static if ( i == -1 ){
//Do something
}
}
String Metaprogramming
Am new to D programming, am considering it since it supports
compile-time function execution . My challenge is how can I
re-implement the function below so that it is fully executed in
compile-time. The function should result to tabel1 being computed
at compile-time. There seems to be a lot of mutation happening
here yet I have heard no mutation should take place in
meta-programming as it subscribes to functional programming
paradigm.
void computeAtCompileTime( ref string pattern ,ref int[char]
tabel1){
int size = to!int(pattern.length) ;
foreach( c; ALPHABET){
tabel1[c] = size;
}
for( int i=0;isize -1 ; ++i){ //Initialise array
tabel1[pattern[i]] = size -i-1;
pragma(msg, format(reached pattern
table1[pattern[i]]=(%s) here,
table1[pattern[i]].stringof ~ v=~ (size
-i-1).stringof));
}
}
Re: String Metaprogramming
On Saturday, 18 July 2015 at 16:01:25 UTC, Nicholas Wilson wrote:
On Saturday, 18 July 2015 at 13:48:20 UTC, Clayton wrote:
[...]
[...]
change function signature to
int[char] function(string) or as the char type is the index
probably better of as
int[256] function(string). also probably no need to take
pattern by ref as it is effectively struct{ size_t length;
char* ptr;}. also we aren't going to modify it.
int[256] computeAtCompileTime(string pattern)
{
[...]
pattern.length is a size_t no need to change its type in
another variable. you are unlikely to be dealing with string
longer than 2^32 (also signedness) but w/e
int[256] ret; // implicitly initialised to int.init
(i.e. 0)
[...]
can just foreach over pattern
foreach(i, c; pattern)
ret[c] = pattern.length - i -1;
[...]
[...]
if you want this to be not callable at runtime then wrap the
main body (sans variable declaration) with
if (__ctfe)
{
...
}
Thanks Nicholas , I have integrated some of your advice on the
edited code i.e. foreach and ref in pattern . Hope I fully
understood what you meant. Am yet to look whether I still need
to change the signature . I have heared there are two approaches
to this, Where does one really draw the line between CTFE and
Template metaprogramming?
Re: String Metaprogramming
On Saturday, 18 July 2015 at 13:56:36 UTC, Adam D. Ruppe wrote:
On Saturday, 18 July 2015 at 13:48:20 UTC, Clayton wrote:
There seems to be a lot of mutation happening here yet I have
heard no mutation should take place in meta-programming as it
subscribes to functional programming paradigm.
That's not true in D, you can just write a regular function and
evaluate it in a compile time context, like initializing a
static variable.
You usually don't need to write special code for compile time
stuff in D.
Thanks , you were right . It seems there are some key words
though which one has to use so that the code gets executed on
compile-time .For example I had to change the second forloop to a
foreach loop, and then put and enum to ensure that
TableFromCompiler gets evaluated at compiletime. Having written
the code this way though gives rise to some other question, D
supports 2 approches to compiletime metaprogramming i.e. CTFE and
Templates, it seems am not very sure which paradigm my code falls
in.
import std.stdio;
import std.string;
import std.conv;
I[C] computeAtCompileTime(S ,C,I)( const S pattern ){
I[C] table1;
const int size = to!int(pattern.length) ;//Length of the
pattern to be matched
foreach( c; ALPHABET){ //Initialise array
table1[c] = size;
}
foreach(i; 0..size-1){
table1[pattern[i]] = size -i-1;
}
return table1;
}
void main(){
enum TableFromCompiler = computeAtCompileTime!(const string
,char, int)(pattern);
writeln(TableFromCompiler);
}
