Any suggestions on dmd error message formatting?
Hi D So the compile error messages getting from dmd are starting to remind me of the notorious 130 line error message I once got from a C++ compiler for missing a comma in a template. :-/ (After fixing that bug, I left work early and came back the next day with a python book.) So, like the noob I am, I've been copying error messages to a text editor, deleting all the @ annotations, replacing common patterns with short tokens, indenting the result, and then trying to understand the problem. I figured this community is so inventive that I'm obviously doing it wrong and that there is a better way. So does anyone have any suggestions on how I make error messages like this one more grokable? ``` das2/range.d(359,31): Error: constructor das2.range.PriorityRange!(DasRange!(Tuple!(int, int)[], int function(Tuple!(int, int)) pure nothrow @nogc @safe, int function(Tuple!(int, int)) pure nothrow @nogc @safe, Tuple!(int, int), int), int function() pure nothrow @nogc @safe).PriorityRange.this(DasRange!(Tuple!(int, int)[], int function(Tuple!(int, int)) pure nothrow @nogc @safe, int function(Tuple!(int, int)) pure nothrow @nogc @safe, Tuple!(int, int), int) range, int function(Tuple!(int, int)) priority) is not callable using argument types (DasRange!(Tuple!(int, int)[], int function(Tuple!(int, int)) pure nothrow @nogc @safe, int function(Tuple!(int, int)) pure nothrow @nogc @safe, Tuple!(int, int), int), int function() pure nothrow @nogc @safe) ``` As always, your advice is much appreciated
Re: Filter for opDispatch?
On Friday, 14 May 2021 at 22:39:29 UTC, frame wrote: When using opDispatch() Thanks! I stumbled around with static asserts and mixins... totally forgot about the constraints but they will to the trick.
Re: Filter for opDispatch?
On Friday, 14 May 2021 at 22:39:29 UTC, frame wrote:
When using opDispatch()
- how can I tell the compiler that I do not want to handle some
calls? Some code is testing for range methods (empty, front,
popFront) and I don't know where and which side effects it
causes.
Use a template constraint. For example:
auto opDispatch(string method, Args...)(Args args)
if (shouldHandle!method)
{
// ...
}
...where `shouldHandle` checks the method name and returns `true`
if you want to handle it, or `false` if you don't.
- how can I dismiss calls from __traits(compiles)?
You can't.
Re: Filter for opDispatch?
On Friday, 14 May 2021 at 22:39:29 UTC, frame wrote: - how can I tell the compiler that I do not want to handle some calls? Put a template constraint on it. `void opDispatch(string s)() if(s == "whatever")` or minimally like `if(s != "popFront")` This kind of thing is why I always put opDispatch on a helper thing now though, and still do the != "popFront" just to stop the ducktypers.
Filter for opDispatch?
When using opDispatch() - how can I tell the compiler that I do not want to handle some calls? Some code is testing for range methods (empty, front, popFront) and I don't know where and which side effects it causes. - how can I dismiss calls from __traits(compiles)?
Re: Can rdmd (under Windows 10) use linker other than Optlink?
On 15/05/2021 9:42 AM, DLearner wrote: I am getting 'Error 42: Symbol Undefined' while testing some (fairly) complex imports. There was a reference in January to an Optlink bug that seemed like it could be responsible. If rdmd can use another linker (and one was recommended), I might be able to test things further. Best regards Just don't use -m32, i.e. -m64 or -m32mscoff
Can rdmd (under Windows 10) use linker other than Optlink?
I am getting 'Error 42: Symbol Undefined' while testing some (fairly) complex imports. There was a reference in January to an Optlink bug that seemed like it could be responsible. If rdmd can use another linker (and one was recommended), I might be able to test things further. Best regards
Re: SDL2 Android vulkan question
On Sunday, 2 May 2021 at 13:43:11 UTC, evilrat wrote: Anyway, I might try to look at this next weekend. Do you have this project available on github/google drive? Open-sourced the code see: https://github.com/DannyArends/CalderaD Danny
Re: Learning D
On Friday, 14 May 2021 at 15:30:06 UTC, Imperatorn wrote: https://www.amazon.com/Programming-Language-Former-Python-Developers-ebook/dp/B08MD7ZB2X Anyone read it? From the thread title, I thought you were asking about my book!
Re: how do I implement opSlice for retro range?
On Friday, 14 May 2021 at 14:14:03 UTC, Steven Schveighoffer
wrote:
On 5/13/21 11:49 PM, Jack wrote:
[...]
Just slice the `a`, appropriately. You have to translate the
indexes back into the original array.
```d
auto opSlice(size_t start, size_t end)
{
return typeof(this)(a[$ - end .. $ - start]);
}
```
You should also define `length`, `save`, `opIndex`, and
`opDollar` so that it fits in the range hierarchy as a proper
random-access range.
But I question whether you shouldn't just use `std.range.retro`
directly? It does all this for you:
```d
// inside A
auto retro() {
import std.range : retro;
return arr.retro;
}
```
-Steve
much easier, I'll be just using the one from std.range. Thanks!
Re: how do I implement opSlice for retro range?
On Friday, 14 May 2021 at 10:00:44 UTC, Christian Köstlin wrote: On 2021-05-14 05:49, Jack wrote: [...] arr.retro()[0..2] already works. see https://run.dlang.io/is/U8u3br oh, how i silly of i didn't notice that before
Re: Learning D
On Friday, 14 May 2021 at 15:30:06 UTC, Imperatorn wrote: https://www.amazon.com/Programming-Language-Former-Python-Developers-ebook/dp/B08MD7ZB2X Anyone read it? Haven't read it, the title has me at the first five words though.
Learning D
https://www.amazon.com/Programming-Language-Former-Python-Developers-ebook/dp/B08MD7ZB2X Anyone read it?
Re: ref struct member function
On Friday, 14 May 2021 at 10:00:28 UTC, PinDPlugga wrote:
Hi thank you both for your answers. I had understood from an
earlier chapter how this could introduce a bug, but I was
confused because the warning suggests attaching ```return``` to
the parameter, which is empty in the declaration.
The error message here is definitely not as good as it could be.
As a general rule, if you want to apply an attribute to the
`this` reference in a member function, you write it after the
parameter list:
struct S
{
// ...
auto memberFunc() const scope
{
// `this` is const and scope
}
auto anotherOne() share inout
{
// `this` is shared and inout
}
}
Re: how do I implement opSlice for retro range?
On 5/13/21 11:49 PM, Jack wrote:
How can I implement ranges in the retro range? I'd like to do this
without allocate a new array with .array from std.array, can I do that?
use like this:
```d
auto arr = [1, 2, 3, 4, 5];
auto a = new A!int(arr);
auto b = a.retro[0 .. 2]; // 4, 5
```
the class:
```d
class A(T)
{
private T[] arr;
this(T[] a)
{
arr = a;
}
auto opIndex() nothrow
{
return Range(arr);
}
auto retro() { return RangeRetro(arr); }
protected static struct Range
{
T[] a;
T front() { return a[0]; }
T back() { return a[$ - 1]; }
void popFront() { a = a[1 .. $]; }
bool empty() { return a.length == 0; }
}
protected static struct RangeRetro
{
import std.range : popFront;
import std.range : popBack;
T[] a;
T front() { return a[$ - 1]; }
T back() { return a[0]; }
void popBack() { a.popFront(); }
void popFront() { a.popBack(); }
bool empty() { return a.length == 0; }
auto opSlice(size_t start, size_t end)
{
???
}
}
}
```
Just slice the `a`, appropriately. You have to translate the indexes
back into the original array.
```d
auto opSlice(size_t start, size_t end)
{
return typeof(this)(a[$ - end .. $ - start]);
}
```
You should also define `length`, `save`, `opIndex`, and `opDollar` so
that it fits in the range hierarchy as a proper random-access range.
But I question whether you shouldn't just use `std.range.retro`
directly? It does all this for you:
```d
// inside A
auto retro() {
import std.range : retro;
return arr.retro;
}
```
-Steve
Re: Scope of 'alias'
On Friday, 14 May 2021 at 14:03:17 UTC, DLearner wrote: So 'alias' only valid from definition to end-of-function, rather than whole function? Best regards Yes. This applies to all definitions inside a function, not just aliases.
Scope of 'alias'
>>>
void foo(pint p1) {
alias pint=uint;
import std.stdio;
writeln("p1 = ", p1);
}
void main() {
alias pint=uint;
pint var1;
var1 = 7;
foo(var1);
}
<<<
Does not compile.
But the rather similar:
alias pint=uint;
void foo(pint p1) {
import std.stdio;
writeln("p1 = ", p1);
}
void main() {
pint var1;
var1 = 7;
foo(var1);
}
<<<
Is fine.
So 'alias' only valid from definition to end-of-function, rather
than whole function?
Best regards
Re: ref struct member function
On 14.05.21 12:00, PinDPlugga wrote:
Hi thank you both for your answers. I had understood from an earlier
chapter how this could introduce a bug, but I was confused because the
warning suggests attaching ```return``` to the parameter, which is empty
in the declaration.
`this` is considered a hidden parameter. Every non-static method has it.
So my next question would be how come ref based operator overloads are
not labelled as return and do not show this warning?
``` D
struct Fraction {
auto n = 0L;
auto d = 1L;
ref Fraction opUnary(string op)()
if (op == "++") {
n += d;
return this;
}
}
ref Fraction foo() {
auto f = Fraction(1, 3);
// Same bug as with reduce
return ++f;
}
```
Note that opUnary is not an ordinary method. It's a template. That means
attributes are inferred [1], including the `return` attribute. I.e., the
compiler adds `return` to the signature for you, just like Steven
suggested you do manually.
Try omitting the return type of `reduce` in your original code:
ref reduce() { ... }
That also enables attribute inference, and your code will compile.
[1] https://dlang.org/spec/function.html#function-attribute-inference
Re: ref struct member function
On Thursday, 13 May 2021 at 19:48:44 UTC, Ali Çehreli wrote:
I was writing this example that shows a use case for the
problem (marked with BUG below):
```D
struct Fraction {
auto n = 0L;
auto d = 1L;
// ... other bits ...
ref Fraction reduce() {
import std.numeric : gcd;
// v = gcd(n, d);
// if (v > 1) {
// n /= v;
// d /= v;
// }
return this;
}
// ... etc ...
}
ref foo() {
import std.stdio : writeln;
auto f = Fraction(3, 9);
// BUG: Returns reference to an object on the stack
return f.reduce();
}
void main() {
// Refers to a temporary (it would be a copy without the &)
auto f = ();
// Do some unrelated things hoping that space for dead
objects on
// the stack will be reused.
import std.stdio;
import std.random;
writeln("doing something else: ", uniform(0, 6));
writeln(f.d); // Access dead and overwritten object (does NOT
print
// 9 on my system)
}
```
Putting 'return' where Steve shows makes the compiler guard us
against this misuse and the program thankfully does not compile.
Ali
Hi thank you both for your answers. I had understood from an
earlier chapter how this could introduce a bug, but I was
confused because the warning suggests attaching ```return``` to
the parameter, which is empty in the declaration.
So my next question would be how come ref based operator
overloads are not labelled as return and do not show this warning?
``` D
struct Fraction {
auto n = 0L;
auto d = 1L;
ref Fraction opUnary(string op)()
if (op == "++") {
n += d;
return this;
}
}
ref Fraction foo() {
auto f = Fraction(1, 3);
// Same bug as with reduce
return ++f;
}
```
Re: how do I implement opSlice for retro range?
On 2021-05-14 05:49, Jack wrote:
How can I implement ranges in the retro range? I'd like to do this
without allocate a new array with .array from std.array, can I do that?
use like this:
```d
auto arr = [1, 2, 3, 4, 5];
auto a = new A!int(arr);
auto b = a.retro[0 .. 2]; // 4, 5
```
the class:
```d
class A(T)
{
private T[] arr;
this(T[] a)
{
arr = a;
}
auto opIndex() nothrow
{
return Range(arr);
}
auto retro() { return RangeRetro(arr); }
protected static struct Range
{
T[] a;
T front() { return a[0]; }
T back() { return a[$ - 1]; }
void popFront() { a = a[1 .. $]; }
bool empty() { return a.length == 0; }
}
protected static struct RangeRetro
{
import std.range : popFront;
import std.range : popBack;
T[] a;
T front() { return a[$ - 1]; }
T back() { return a[0]; }
void popBack() { a.popFront(); }
void popFront() { a.popBack(); }
bool empty() { return a.length == 0; }
auto opSlice(size_t start, size_t end)
{
???
}
}
}
```
arr.retro()[0..2] already works.
see https://run.dlang.io/is/U8u3br
Re: Passing a byLine as an argument to InputRange
On Thursday, 13 May 2021 at 18:31:41 UTC, Ali Çehreli wrote: On 5/13/21 11:29 AM, Ali Çehreli wrote: create a dynamic InputRange!string object for dynamic polymorphism that InputRange provides. And that's achieved by function inputRangeObject(): Some examples: http://ddili.org/ders/d.en/ranges_more.html#ix_ranges_more.polymorphism,%20run-time Ali This book has saved my life many times! ☀
