Re: Setting field of struct object
On Monday, 22 January 2024 at 08:54:21 UTC, Danilo wrote: On Monday, 22 January 2024 at 08:35:01 UTC, Joel wrote: [...] Nonetheless, this usually used with Objects (new class/struct instances), like so: ```d import std; [...] Fluent Interface
Re: Range handling difficulties
On Wednesday, 24 April 2024 at 14:22:10 UTC, H. S. Teoh wrote: On Wed, Apr 24, 2024 at 08:08:06AM +, Menjanahary R. R. via Digitalmars-d-learn wrote: [...] evenfib.until!(n => n > 4_000_000).sum.writeln; T Thanks a lot! You've made my day
Range handling difficulties
I tried to solve Project Euler [problem #2](https://projecteuler.net/problem=2) using [Recurrence/recurrence](https://dlang.org/library/std/range/recurrence.html). Assuming `genEvenFibonacci` is the appropriate funtion in Explicit form, I got what I need like so: ``` auto evenfib = recurrence!genEvenFibonacci(2uL, 8uL); writeln; evenfib.take(11).sum.writeln; ``` But that's like cheating because there is no prior knowledge of `11`. I just got it manually by peeking at the sequence `[2, 8, 34, 144, 610, 2584, 10946, 46368, 196418, 832040, 3524578, 14930352]`. `14930352` must be filtered out because beyond the limit set! How to fix that properly using all the standard library capabilities programatically? I'm thinking of Range and/or std.algorithm.
Re: Mutability issue
On Saturday, 23 March 2024 at 20:49:14 UTC, Nick Treleaven wrote:
On Saturday, 23 March 2024 at 19:30:29 UTC, Menjanahary R. R.
wrote:
for (T candidate = T(5); candidate * candidate <= n;
candidate += T(6)) {
When T is `const int`, the above code declares and initializes
a constant variable:
```d
const int candidate = const int(5);
```
Then, at the end of each loop iteration, it does:
```d
candidate += const int(6);
```
So you are trying to modify a constant. Constants can only be
initialized, never assigned.
T candidate = (n % T(2) == T(0)) ? n + T(1) : n + T(2); //
Start from next Odd
for (;; candidate += T(2)) { // Skip even
Same here, you declare a constant then try to assign to it at
the end of each loop iteration.
Thanks for your prompt answer.
Re: Mutability issue
On Saturday, 23 March 2024 at 20:38:40 UTC, Jonathan M Davis wrote: On Saturday, March 23, 2024 1:30:29 PM MDT Menjanahary R. R. via Digitalmars- d-learn wrote: [...] Well, when nextPrime is instantiated, the type of T is inferred from the function argument. So, if num is int, then T is int, whereas if num is const int, then T is const int. The same with isPrime. [...] Thanks for your prompt answer. It works like a charm. It's always a pleasure to learn from the Dlang community.
Re: Mutate immutable inside shared static constructor
On Saturday, 23 March 2024 at 21:59:57 UTC, Nick Treleaven wrote: On Saturday, 23 March 2024 at 21:53:43 UTC, Jonathan M Davis wrote: Yes, it's a bug. It's a clear violation of the type system if a non-mutable variable is ever given a value more than once. It should be initialized, and then it should be treated as illegal to ever assign to it - or to do anything else which would mutate it. So, clearly, the logic in static constructors with regards to non-mutable variables is overly simple at the moment. Thanks, filed: https://issues.dlang.org/show_bug.cgi?id=24449 Thanks for your prompt answer.
Mutability issue
The next code works as is but ...
```
import std.stdio;
import std.traits;
bool isPrime(T)(T n) if (isIntegral!T) {
if (n <= T(3)) return n > T(1);
if (n % T(2) == T(0) || n % T(3) == T(0)) return false;
for (T candidate = T(5); candidate * candidate <= n;
candidate += T(6)) {
if (n % candidate == T(0) || n % (candidate + T(2)) ==
T(0)) {
return false;
}
}
return true;
}
T nextPrime(T)(T n) if (isIntegral!T) {
if (n < T(2))
return T(2);
T candidate = (n % T(2) == T(0)) ? n + T(1) : n + T(2); //
Start from next Odd
for (;; candidate += T(2)) { // Skip even
if (isPrime(candidate)) {
return candidate;
}
}
}
void main() {
int num = 10; // Example starting number
writeln("\nNext prime after ", num, " is ", nextPrime(num));
}
```
... it doesn't at all once I change `int num = 10;` to `const int
num = 10;`. I'm confused
How to fix it?
Re: How to unpack a tuple into multiple variables?
On Wednesday, 7 February 2024 at 05:03:09 UTC, Gary Chike wrote:
... But overall it's an elegant way to indirectly add names to
tuples in D for ergonomic access. Nice find!
---
Refactored it a bit to have a ready to run and easy to grasp code.
Enjoy!
```d
import std.stdio : writefln;
import std.typecons: tuple;
// Name a Tuple's fields post hoc by copying the original's
fields into a new Tuple.
template named(names...) {
auto named(T)(ref auto T t) if (names.length <=
T.Types.length) =>
tuple!names(t.expand[0..names.length]);
}
// Define variables corresponding to a Tuple's fields in the
current scope,
// whose identifiers are given by `names`.
mixin template Unpack(alias t, names...)
if (names.length <= t.Types.length) {
static foreach (i, n; names)
mixin("auto ", n, " = t[i];");
}
void main()
{
auto getUser() => tuple("John Doe", 32);
//
auto u = getUser().named!("name", "age");
writefln("%s (%d)", u.name, u.age); // John Doe (32)
// You could also do this.
with (getUser().named!("name", "age"))
writefln("%s (%d)", name, age); // John Doe (32)
//
mixin Unpack!(u, "name", "age");
writefln("%s (%d)", name, age); // John Doe (32)
}
```
Re: how can I load html files and not .dt or diet files in vibe.d
On Thursday, 1 February 2024 at 03:20:31 UTC, dunkelheit wrote:
this is my code, I'm a begginer on vibe, and I want to use html
and not diet files
`import vibe.vibe;
void main()
{
auto settings = new HTTPServerSettings;
settings.port = 8080;
settings.bindAddresses = ["::1", "127.0.0.1"];
auto listener = listenHTTP(settings, );
scope (exit)
{
listener.stopListening();
}
logInfo("Please open http://127.0.0.1:8080/ in your browser.");
runApplication();
}
void hello(HTTPServerRequest req, HTTPServerResponse res)
{
res.render!"hola.dt";
}`
I tried to load my html through iframe but it not works
!!! 5
html
body
h1 hello diet
-iframe("hola.html")
please help me :')
Explore this link https://github.com/D-Programming-GDC/gdcproject
for potential sources of inspiration.
