Re: BigInt.toString
On Thursday, 4 August 2022 at 01:32:15 UTC, Salih Dincer wrote:
I guess I wrote the following anything like that you want.
```d
void main()
{
import std.bigint,
std.string : representation;
BigInt i = 1001;
auto val = i.to!(dchar[]);
assert(val.representation == [49, 48, 48, 49]);
}
```
Is that what you want?
SDB@79
Not exactly. Anyways, it has already been solved.
Re: BigInt.toString
On Thursday, 4 August 2022 at 01:05:31 UTC, H. S. Teoh wrote:
Don't call .toString directly. Instead, use std.format.format:
```d
import std;
void main() {
auto x = BigInt("123123123123123123123123123123123123");
string s = format("%s", x); // this gives you the string
representation
writeln(s); // prints "123123123123123123123123123123123123"
// If you need to convert to dchar[]:
dstring ds = s.to!(dchar[]);
// Or if you want a direct formatting into dchar[] without
going
// through a string intermediate:
auto app = appender!(dchar[]);
app.formattedWrite("%s", x");
dchar[] dcharArray = app.data; // now you have your dchar[]
}
```
Hope this is clear.
T
Thank you. This worked.
Re: BigInt.toString
On Thursday, 4 August 2022 at 00:45:44 UTC, Ruby The Roobster
wrote:
How exactly can one store the string representation of a
BigInt? The seemingly obvious:
dchar[] is necessary for my project.
Assume that val is a BigInt with
a value set earlier:
```d
val.toString(ret, "%d");
```
doesn't work.
I guess I wrote the following anything like that you want.
```d
void main()
{
import std.bigint,
std.string : representation;
BigInt i = 1001;
auto val = i.to!(dchar[]);
assert(val.representation == [49, 48, 48, 49]);
}
```
Is that what you want?
SDB@79
Re: BigInt.toString
On Thu, Aug 04, 2022 at 12:45:44AM +, Ruby The Roobster via
Digitalmars-d-learn wrote:
> How exactly can one store the string representation of a BigInt? The
> seemingly obvious
>
> ```d
> //...
> dchar[] ret; //dchar[] is necessary for my project
> //Assume that val is a BigInt with a value set earlier:
> val.toString(ret, "%d");
> //...
> ```
>
> doesn't work. I am using x86_64 windows with -m64, and v2.100.1(LDC2
> 1.30.0).
Don't call .toString directly. Instead, use std.format.format:
```d
import std;
void main() {
auto x = BigInt("123123123123123123123123123123123123");
string s = format("%s", x); // this gives you the string representation
writeln(s); // prints "123123123123123123123123123123123123"
// If you need to convert to dchar[]:
dstring ds = s.to!(dchar[]);
// Or if you want a direct formatting into dchar[] without going
// through a string intermediate:
auto app = appender!(dchar[]);
app.formattedWrite("%s", x");
dchar[] dcharArray = app.data; // now you have your dchar[]
}
```
Hope this is clear.
T
--
Which is worse: ignorance or apathy? Who knows? Who cares? -- Erich Schubert
Re: MMFile usage
On Thu, Aug 04, 2022 at 12:35:55AM +, Alex Burton via Digitalmars-d-learn wrote: > Hi, > I want to use MmFile to manage memory mapped files. I want multiple > processes to be able to read in many files using the virtual memory > system to page them in and reuse the memory. > > If I read the contents of the file, I can cast it to immutable and > then I get segfaults when accessing the data. You need to keep the MmFile instance around as long as you're using the memory, since it will unmap the memory when the GC collects it. > Or I have to .dup the data, causing memory allocation in addition to > the paging to get the data in the first place. That would defeat the purpose of using MmFile in the first place. > Is this special memory not managed by the GC ? Do I need to keep all > the MmFile references around to avoid segfaults ? [...] Memory-mapped memory is not managed by the GC; it's managed by the OS. The MmFile class, however, will unmap the memory upon destruction, so you need to keep at least one reference to it live throughout the course of your threads accessing the memory. Otherwise you will get segfaults after the MmFile is collected, because then it will unmap the memory and all your references will become invalid. Sharing the memory among threads can be done by just passing the memory reference to the threads. It will be up to you, however, to manage synchronization of access if you're planning to write to the memory. If not, you can probably just cast the memory reference to immutable and pass that around to threads. Do NOT cast the MmFile object itself to immutable, though. I'm almost certain that'll break it because it probably needs to keep internal state in order to manage the memory mapping with the OS. Only cast the slice returned by Mmfile.opSlice, not the MmFile object itself. T -- Why is it that all of the instruments seeking intelligent life in the universe are pointed away from Earth? -- Michael Beibl
BigInt.toString
How exactly can one store the string representation of a BigInt? The seemingly obvious ```d //... dchar[] ret; //dchar[] is necessary for my project //Assume that val is a BigInt with a value set earlier: val.toString(ret, "%d"); //... ``` doesn't work. I am using x86_64 windows with -m64, and v2.100.1(LDC2 1.30.0).
MMFile usage
Hi, I want to use MmFile to manage memory mapped files. I want multiple processes to be able to read in many files using the virtual memory system to page them in and reuse the memory. If I read the contents of the file, I can cast it to immutable and then I get segfaults when accessing the data. Or I have to .dup the data, causing memory allocation in addition to the paging to get the data in the first place. Is this special memory not managed by the GC ? Do I need to keep all the MmFile references around to avoid segfaults ? Alex
Re: Obsecure problem 2
On Wednesday, 3 August 2022 at 19:11:51 UTC, pascal111 wrote: On Wednesday, 3 August 2022 at 18:53:35 UTC, jfondren wrote: On Wednesday, 3 August 2022 at 18:33:37 UTC, pascal111 wrote: I changed it to "x=notfunny(x);" and has the same result. Now you are changing the value of the temporary loop variable that is still immediately discarded afterwards. You should return a new range that has the values you want, not try to mutate the range you're given. You should provide a code instead of describing my mistakes!! I agree to the extent that I wanted to do so, and might still have if a delivery hadn't interrupted by post. But one way to encourage others to put in more effort is put in effort yourself. Here you have your first post, where you didn't use 'preview' to check that your formatting worked, or review when linked Markdown guide to see what the problem was when it didn't work. In that post you also didn't describe what the problem was or ask any question, or say what you wanted to accomplish. It wasn't until your second post that it was even clear to me that you wanted to reimplement `map`. I thought the addition was a placeholder. The thread title is also a placeholder title for a thread. In your second and third posts, it didn't come across at all that you'd put much thought into your questions before asking them. The second post--just look at your code. There's a function call and data going nowhere. That should be pretty easy to see. For the third post, if you thought that 'foreach' aliased the members of a range to the degree that simple assignment would update the range, you could test that thought in an instant: ``` $ rdmd --eval 'auto a = [1, 2, 3]; foreach (n; a) n = 0; writeln(a)' [1, 2, 3] ``` It seemed to me that with these quickly asked questions that you're treating the thread like an ongoing interpersonal dialogue where questions are cheap. That's fine, really. I didn't mind that you didn't put in a lot of effort because it also didn't require a lot of effort to help you. But if you're going to complain about it, at least put the effort into asking for what you want at the outset. The last thing that discouraged me from writing a full example is that I wasn't sure that I'd really be helping you. If you're trying to do this, don't you have a range tutorial open? That should already be pretty well-written already. Now that I've helped you with some incidental problems you should get back to the tutorial and see where you got things mixed up. My guess was that you didn't realize you should be returning a new range, and not trying to modify the range you were given. If you don't have a tutorial open, the first link at https://dlang.org/phobos/std_range.html is pretty good: http://ddili.org/ders/d.en/ranges.html You won't find the exact thing you want to do, but if you put that aside and thoroughly go through that chapter, the only way you won't be able to do what you want to do is if you get caught up again by some other more fundamental issue with D. The worst likely outcome is that you'll get something that works but that isn't a great way to do it. You should post that code here for feedback.
Re: Obsecure problem 2
On Wednesday, 3 August 2022 at 19:11:51 UTC, pascal111 wrote: On Wednesday, 3 August 2022 at 18:53:35 UTC, jfondren wrote: On Wednesday, 3 August 2022 at 18:33:37 UTC, pascal111 wrote: I changed it to "x=notfunny(x);" and has the same result. Now you are changing the value of the temporary loop variable that is still immediately discarded afterwards. You should return a new range that has the values you want, not try to mutate the range you're given. You should provide a code instead of describing my mistakes!! No need for a code. See, there is a keyword called `ref`, that can be used both in function parameters and in foreach loops, and it is the equivalent of a pointer to the type specified, but it is automatically dereferenced. As arrays are themselves reference types, you don't need to change the parameter from `Range range` to `ref Range range`. On the other hand, `int` in it of itself isn't a reference type, meaning that to modify the actual value, you need to change the foreach loop to be: ```d foreach(ref x; range) x = notfunny(x); ``` Proof: I tested it, and it works.
Re: Obsecure problem 2
On Wednesday, 3 August 2022 at 18:53:35 UTC, jfondren wrote: On Wednesday, 3 August 2022 at 18:33:37 UTC, pascal111 wrote: I changed it to "x=notfunny(x);" and has the same result. Now you are changing the value of the temporary loop variable that is still immediately discarded afterwards. You should return a new range that has the values you want, not try to mutate the range you're given. You should provide a code instead of describing my mistakes!!
Re: Obsecure problem 2
On Wednesday, 3 August 2022 at 18:33:37 UTC, pascal111 wrote: I changed it to "x=notfunny(x);" and has the same result. Now you are changing the value of the temporary loop variable that is still immediately discarded afterwards. You should return a new range that has the values you want, not try to mutate the range you're given.
Re: Obsecure problem 2
On Wednesday, 3 August 2022 at 18:25:50 UTC, jfondren wrote:
On Wednesday, 3 August 2022 at 17:33:40 UTC, pascal111 wrote:
On Wednesday, 3 August 2022 at 17:09:11 UTC, jfondren wrote:
On Wednesday, 3 August 2022 at 16:59:53 UTC, pascal111 wrote:
I tried to make a template that receive lambda expression to
apply it on a given range the user specifies, but I found
non-understood problem:
Compare with:
```D
auto foo(Range)(Range range) { // remove isInputRange!T test
...
lolo.foo!(a=>a+2); // call foo!(f)() rather than
foo!()(f)
```
Ok! the program ran and gives "[12, 66, 654, -98, 54]" without
adding "2" as I requested!! why?!
You call notfunny(x) in a loop, discarding the result of the
addition.
I changed it to "x=notfunny(x);" and has the same result.
Re: Obsecure problem 2
On Wednesday, 3 August 2022 at 17:33:40 UTC, pascal111 wrote:
On Wednesday, 3 August 2022 at 17:09:11 UTC, jfondren wrote:
On Wednesday, 3 August 2022 at 16:59:53 UTC, pascal111 wrote:
I tried to make a template that receive lambda expression to
apply it on a given range the user specifies, but I found
non-understood problem:
Compare with:
```D
auto foo(Range)(Range range) { // remove isInputRange!T test
...
lolo.foo!(a=>a+2); // call foo!(f)() rather than
foo!()(f)
```
Ok! the program ran and gives "[12, 66, 654, -98, 54]" without
adding "2" as I requested!! why?!
You call notfunny(x) in a loop, discarding the result of the
addition.
Re: Obsecure problem 2
On Wednesday, 3 August 2022 at 17:09:11 UTC, jfondren wrote:
On Wednesday, 3 August 2022 at 16:59:53 UTC, pascal111 wrote:
I tried to make a template that receive lambda expression to
apply it on a given range the user specifies, but I found
non-understood problem:
Compare with:
```D
auto foo(Range)(Range range) { // remove isInputRange!T test
...
lolo.foo!(a=>a+2); // call foo!(f)() rather than
foo!()(f)
```
Ok! the program ran and gives "[12, 66, 654, -98, 54]" without
adding "2" as I requested!! why?!
Re: Obsecure problem 2
On Wednesday, 3 August 2022 at 16:59:53 UTC, pascal111 wrote:
I tried to make a template that receive lambda expression to
apply it on a given range the user specifies, but I found
non-understood problem:
Compare with:
```D
auto foo(Range)(Range range) { // remove isInputRange!T test
...
lolo.foo!(a=>a+2); // call foo!(f)() rather than
foo!()(f)
```
Obsecure problem 2
I tried to make a template that receive lambda expression to
apply it on a given range the user specifies, but I found
non-understood problem:
'''D
module main;
import std.stdio;
import std.functional;
template foo(alias predicate)
if (is(typeof(unaryFun!predicate)))
{
alias notfunny=unaryFun!predicate;
auto foo(Range)(Range range) if (isInputRange!(Unqual!Range)){
foreach(x; range)
notfunny(x);
return range;}
}
int main()
{
int[] lolo = [12, 66, 654, -98, 54];
lolo.foo(a=>a+2);
lolo.writeln;
return 0;
}
'''
Re: Choosing the correct compiler version
I don't know if this helps but i have to do, export CC=/usr/local/bin/gcc with ldc2. I don't know why it works with gcc but not with llvm/clang.
Re: How to cast away shared?
On Wednesday, 3 August 2022 at 13:00:05 UTC, Paul Backus wrote: On Wednesday, 3 August 2022 at 12:50:17 UTC, Ruby The Roobster wrote: Any way to 'cast away' shared for an unknown type T? There's actually an `Unshared` template for this in `std.traits`, but for some reason it's `private`, so you can't use it directly. Fortunately, it's only two lines: ```d alias Unshared(T) = T; alias Unshared(T: shared U, U) = U; ``` Once you have this, you can write `cast(Unshared!T)`. Thank you. This really helped.
Re: How to cast away shared?
On Wednesday, 3 August 2022 at 12:50:17 UTC, Ruby The Roobster wrote: Any way to 'cast away' shared for an unknown type T? There's actually an `Unshared` template for this in `std.traits`, but for some reason it's `private`, so you can't use it directly. Fortunately, it's only two lines: ```d alias Unshared(T) = T; alias Unshared(T: shared U, U) = U; ``` Once you have this, you can write `cast(Unshared!T)`.
How to cast away shared?
Any way to 'cast away' shared for an unknown type T?
Re: How to find all modules in a package?
On Wednesday, 3 August 2022 at 03:36:55 UTC, Domain wrote:
I want to find out all public functions in all modules in a
package. Can I do that at compile time?
You can do something like that:
```d
static foreach (sym; __traits(allMembers, mixin("std.string")))
{
pragma(msg, sym.stringof);
}
```
Then you would have to check if `sym` is a template or function
or something else.
Re: How to find all modules in a package?
On Wednesday, 3 August 2022 at 03:36:55 UTC, Domain wrote: I want to find out all public functions in all modules in a package. Can I do that at compile time? No, D packages are not closed; anyone can add new modules to them at any time.
Re: How to find all modules in a package?
On Wednesday, 3 August 2022 at 03:36:55 UTC, Domain wrote: I want to find out all public functions in all modules in a package. Can I do that at compile time? I think it's not possible.
Re: Request assistance resolving linker error: Undefined symbol(s) for architecture x86_64
On Wednesday, 3 August 2022 at 09:39:36 UTC, ryuukk_ wrote: Does adding ```-m64``` work I'm using macOS so I don't think that applies. But no, it doesn't do anything for me. Thanks, --anonymouse
Re: Request assistance resolving linker error: Undefined symbol(s) for architecture x86_64
Does adding ```-m64``` work
Re: A look inside "filter" function defintion
leyts try very rough simlified concept: template itself - is compile-time program (parameterizable), it can generate some code for you. template instantiation (like "calling") with "!" - instruct compiler to "start this compile-time program here with this parameters".
