Re: observation: D getting a bit complex
On Sunday, 30 August 2015 at 02:42:30 UTC, Spacen Jasset wrote: immutable(ElementEncodingType!(ElementType!Range))[] buildPath(Range)(Range segments) if (isInputRange!Range isSomeString!(ElementType!Range)); pure nothrow @safe immutable(C)[] buildPath(C)(const(C)[][] paths...) if (isSomeChar!C); I understand how you feel. When I was learning D, the docs where almost impenetrable because of this. But when I got into some of the more advanced features of D, I found these explicit function signatures invaluable. This essentially tells you that the function takes either a range of strings, or it can take indefinite number of strings as different arguments. Also, examples underneath the function signature help new comers understand how to call the function without having to parse it.
Re: Error Compiling with -debug swtich
On Thursday, 27 August 2015 at 22:09:07 UTC, Jordan Wilson wrote:
Hello,
Just wondering why compiling the following fails with the
-debug switch, but appears to compile and execute fine without
it:
import std.stdio;
import std.algorithm;
import std.container;
int main(string[] args) {
Array!string letters = [b,a,c];
sort(letters[]);
writeln (letters[]); // [a,b,c]
return 0;
}
With the -debug switch, I get:
src\phobos\std\range\package.d(7180): Error:
'std.range.SortedRange!(RangeT!(Array!string), a
b).SortedRange.dbgVerifySorted' is not nothrow
src\phobos\std\algorithm\sorting.d(982): Error: template
instance std.range.assumeSorted!(a b,
RangeT!(Array!string)) error instantiating
Without the switch, everything seems to work fine...(I'm using
DMD 2.068.0)
Thanks,
Jordan
filed a BR: https://issues.dlang.org/show_bug.cgi?id=14981
Re: observation: D getting a bit complex
On Sunday, 30 August 2015 at 10:42:24 UTC, Spacen Jasset wrote: On Sunday, 30 August 2015 at 07:36:55 UTC, BBasile wrote: On Sunday, 30 August 2015 at 02:42:30 UTC, Spacen Jasset wrote: immutable(ElementEncodingType!(ElementType!Range))[] buildPath(Range)(Range segments) if (isInputRange!Range isSomeString!(ElementType!Range)); pure nothrow @safe immutable(C)[] buildPath(C)(const(C)[][] paths...) if (isSomeChar!C); this is stodgy, particularly in a console with line wrapping at 80 chars. To be fair it was the docs page I was reading not a compiler diagnostic, but I did get something a bit shorter from the compiler once. Oh i see. Then i don't agree. Doc is very nice. The problem is that you have to know std.traits and std.range to understand the constraints. It's not always obvious but i'd say it's about 30 or 40 functions.
Re: Reading and converting binary file 2 bits at a time
On Sunday, 30 August 2015 at 00:02:16 UTC, anonymous wrote: On Saturday, 29 August 2015 at 23:34:47 UTC, Gary Willoughby wrote: But it might not be safe: http://forum.dlang.org/thread/ztefzijqhwrouzlag...@forum.dlang.org That link just takes me to this thread here again. Here's the correct link. http://forum.dlang.org/thread/sugxdshytelayxnst...@forum.dlang.org
Re: observation: D getting a bit complex
On Sunday, 30 August 2015 at 07:36:55 UTC, BBasile wrote: On Sunday, 30 August 2015 at 02:42:30 UTC, Spacen Jasset wrote: immutable(ElementEncodingType!(ElementType!Range))[] buildPath(Range)(Range segments) if (isInputRange!Range isSomeString!(ElementType!Range)); pure nothrow @safe immutable(C)[] buildPath(C)(const(C)[][] paths...) if (isSomeChar!C); this is stodgy, particularly in a console with line wrapping at 80 chars. Could have been written as auto buildPath(Range)(Range segments) if (isInputRange!Range isSomeString!(ElementType!Range)); but having an explicit return type is super valuable information. But the opportunity to omit it makes implementing a first working version so fast that it is pure joy. And the constraints you need not read - unless you want to understand why your call to the function failed. C++ is just lacking without them. Having them avoids that you always have to handle ridiculous input within your functions and allows to concentrate on meaningful code.
Re: observation: D getting a bit complex
On Sunday, 30 August 2015 at 02:42:30 UTC, Spacen Jasset wrote: immutable(ElementEncodingType!(ElementType!Range))[] buildPath(Range)(Range segments) if (isInputRange!Range isSomeString!(ElementType!Range)); pure nothrow @safe immutable(C)[] buildPath(C)(const(C)[][] paths...) if (isSomeChar!C); this is stodgy, particularly in a console with line wrapping at 80 chars.
Re: observation: D getting a bit complex
On Sunday, 30 August 2015 at 09:55:02 UTC, Dominikus Dittes Scherkl wrote: And the constraints you need not read - unless you want to understand why your call to the function failed. C++ is just lacking without them. Having them avoids that you always have to handle ridiculous input within your functions and allows to concentrate on meaningful code. Maybe we should color thoses things, having syntax highlighting for template and functions signatures would be great.
Re: stuck on opDiv / opBinary
On Sunday, 30 August 2015 at 18:12:40 UTC, BBasile wrote:
On Sunday, 30 August 2015 at 17:02:58 UTC, Spacen Jasset wrote:
[...]
try
---
Vector3 opBinary(string op)(Vector3 rhs)
{
static if (op ==/){}
else static assert(0, op ~ not implemented);
}
---
you used the char litteral delims ('') instead of the strings
ones ().
Ah yes, it's didnt' complain. But anyway that was the wrong
funciton I implemented.
I found the problem. I failed to implement a opDivAssign
Re: How to get the current Timezone
On Saturday, August 29, 2015 05:25:33 rumbu via Digitalmars-d-learn wrote: On Friday, 28 August 2015 at 23:03:16 UTC, Jonathan M Davis wrote: I _really_ wish that Microsoft would just use the TZ database like everyone else... - Jonathan M Davis Starting with Windows 8.1, it does, but only in Windows Runtime (so called modern/store apps). Well, that's good news but ultimately pretty useless. If it's really going ot be of any use to applications in general, then the OS itself needs to be using the TZ database files, and that needs to be accessible via their normal C API, not just the WinRT stuff. But maybe this is a good sign for the future. - Jonathan M Davis
Re: stuck on opDiv / opBinary
On Sunday, 30 August 2015 at 17:02:58 UTC, Spacen Jasset wrote:
I have just added an opDiv to this class, but it doesn't seem
to pick it up.
math/vector.d(30): Error: 'this /= mag' is not a scalar, it is
a Vector3
I can't see why that is, becuase my opMul works in the same
place. Can anyone point out what I have done wrong?
Class Matrix {
void normalise()
{
const float mag = magnitude();
if (mag) {
//this.scalarDivide(mag);
this /= mag; // Not work
this *= 1/mag; // Does work.
}
}
//Vector3 opBinary(string op)(Vector3 rhs) if (op=='/')
Vector3 opDiv(float scalar)
{
Vector3 v = this;
v.scalarDivide(scalar);
return v;
}
}
try
---
Vector3 opBinary(string op)(Vector3 rhs)
{
static if (op ==/){}
else static assert(0, op ~ not implemented);
}
---
you used the char litteral delims ('') instead of the strings
ones ().
Re: What is the D way to map a binary file to a structure?
On Saturday, 29 August 2015 at 12:56:08 UTC, cym13 wrote:
Hi,
Let's say I have a simple binary file whose structure is
well-known. Here is
an example which stores points:
struct Point {
long x;
long y;
long z;
}
struct BinFile {
uintmagicNumber; // Some identifier
ulong pointsNumber;
Point[] points; // Array of pointsNumber points.
}
What is the best way to read some file and fill a structure
with it? Would
reading the file into a void[] and then casting it to the
struct work with
things like internal struct padding?
https://github.com/atilaneves/cerealed
Just pass the bytes obtained from reading the file to
`Decerealiser`.
Atila
Re: observation: D getting a bit complex
On Sunday, 30 August 2015 at 07:36:55 UTC, BBasile wrote: On Sunday, 30 August 2015 at 02:42:30 UTC, Spacen Jasset wrote: immutable(ElementEncodingType!(ElementType!Range))[] buildPath(Range)(Range segments) if (isInputRange!Range isSomeString!(ElementType!Range)); pure nothrow @safe immutable(C)[] buildPath(C)(const(C)[][] paths...) if (isSomeChar!C); this is stodgy, particularly in a console with line wrapping at 80 chars. To be fair is was the docs page I was reading not a compiler diagnostic, but I did get something a bit shorter from the compiler once. It's slighty hard to see that you can give that function a string, and that it can return a string like thing -- although on that score too I've found I have to use char[] in some places instead of string which is to do with immutability, that I've not quite worked that out yet either -- It's just a feeling I have when looking at this now that it is quite complex. I only mention this as it was something that I think other people may notice too, when starting out, or coming back to D. Maybe I've just been doing too much python recently.
Re: observation: D getting a bit complex
On Sunday 30 August 2015 04:42, Spacen Jasset wrote: immutable(ElementEncodingType!(ElementType!Range))[] buildPath(Range)(Range segments) if (isInputRange!Range isSomeString!(ElementType!Range)); pure nothrow @safe immutable(C)[] buildPath(C)(const(C)[][] paths...) if (isSomeChar!C); http://dlang.org/phobos/std_path.html It's less horrible in the /library/ docs: immutable(ElementEncodingType!(ElementType!Range))[] buildPath(Range)( Range segments ) if (isInputRange!Range isSomeString!(ElementType!Range)); immutable(C)[] buildPath(C)( const(C)[][] paths ) pure nothrow @safe if (isSomeChar!C); http://dlang.org/library/std/path/build_path.html The /library/ docs are supposed to replace the current /phobos/ ones, but I don't know what's the latest on that.
Re: stuck on opDiv / opBinary
On Sunday, 30 August 2015 at 17:02:58 UTC, Spacen Jasset wrote:
I have just added an opDiv to this class, but it doesn't seem
to pick it up.
math/vector.d(30): Error: 'this /= mag' is not a scalar, it is
a Vector3
I can't see why that is, becuase my opMul works in the same
place. Can anyone point out what I have done wrong?
Class Matrix {
void normalise()
{
const float mag = magnitude();
if (mag) {
//this.scalarDivide(mag);
this /= mag; // Not work
this *= 1/mag; // Does work.
}
}
//Vector3 opBinary(string op)(Vector3 rhs) if (op=='/')
Vector3 opDiv(float scalar)
{
Vector3 v = this;
v.scalarDivide(scalar);
return v;
}
}
Don't use opMul or opDiv etc, use opBinary
Could you provide a more complete example? It's hard to identify
what the problem is from this snippet.
Re: observation: D getting a bit complex
On Sun, Aug 30, 2015 at 07:36:53AM +, BBasile via Digitalmars-d-learn wrote: On Sunday, 30 August 2015 at 02:42:30 UTC, Spacen Jasset wrote: immutable(ElementEncodingType!(ElementType!Range))[] buildPath(Range)(Range segments) if (isInputRange!Range isSomeString!(ElementType!Range)); pure nothrow @safe immutable(C)[] buildPath(C)(const(C)[][] paths...) if (isSomeChar!C); this is stodgy, particularly in a console with line wrapping at 80 chars. https://issues.dlang.org/show_bug.cgi?id=13676 T -- People who are more than casually interested in computers should have at least some idea of what the underlying hardware is like. Otherwise the programs they write will be pretty weird. -- D. Knuth
Re: stuck on opDiv / opBinary
On 08/30/2015 07:02 PM, Spacen Jasset wrote:
I have just added an opDiv to this class, but it doesn't seem to pick it
up.
math/vector.d(30): Error: 'this /= mag' is not a scalar, it is a Vector3
I can't see why that is, becuase my opMul works in the same place. Can
anyone point out what I have done wrong?
...
import std.math: sqrt;
import std.algorithm: map,sum,canFind;
struct Vector3{
float[3] xyz;
void normalise(){ this/=magnitude(); }
float magnitude(){ return sqrt(xyz[].map!(a=a*a).sum); }
enum scalarOps=[*,/];
enum isScalarOp(string op)=scalarOps.canFind(op);
void scalar(string op)(float scalar)if(isScalarOp!op){
foreach(ref a;xyz) mixin(`a `~op~`=scalar;`);
}
Vector3 opBinary(string op)(float scalar)if(isScalarOp!op){
Vector3 v=this;
v.scalar!op(scalar);
return v;
}
auto opOpAssign(string op)(float rhs)if(isScalarOp!op){
return mixin(`this=this `~op~` rhs`);
}
}
Re: observation: D getting a bit complex
On Sunday, 30 August 2015 at 02:42:30 UTC, Spacen Jasset wrote: The following reminds me of the good old C++ template errors the C++ compiler spits out. Whilst D has fixed that problem, some things have gotten more complex. I just wanted to find a replacement for D1 path join, and found this, but it doesn't seem very easy to wade though this stuff. immutable(ElementEncodingType!(ElementType!Range))[] buildPath(Range)(Range segments) if (isInputRange!Range isSomeString!(ElementType!Range)); pure nothrow @safe immutable(C)[] buildPath(C)(const(C)[][] paths...) if (isSomeChar!C); http://dlang.org/phobos/std_path.html It would take me a lot of time to appeciate what that all means, although I can imagine what it is for. ...just and observation. The complexity is building. With C++ I rarely have trouble finding a good explanation, it's just a really complex language that doesn't get easier when you use it. For D, the documentation is a work in progress, amplifying the learning curve for the things that make life easier for experienced programmers. The official documentation is going to have to take a better approach when dealing with ranges and generic programming because the current approach doesn't work at all.
stuck on opDiv / opBinary
I have just added an opDiv to this class, but it doesn't seem to
pick it up.
math/vector.d(30): Error: 'this /= mag' is not a scalar, it is a
Vector3
I can't see why that is, becuase my opMul works in the same
place. Can anyone point out what I have done wrong?
Class Matrix {
void normalise()
{
const float mag = magnitude();
if (mag) {
//this.scalarDivide(mag);
this /= mag; // Not work
this *= 1/mag; // Does work.
}
}
//Vector3 opBinary(string op)(Vector3 rhs) if (op=='/')
Vector3 opDiv(float scalar)
{
Vector3 v = this;
v.scalarDivide(scalar);
return v;
}
}
Re: stuck on opDiv / opBinary
On Sunday, 30 August 2015 at 20:09:25 UTC, Timon Gehr wrote:
On 08/30/2015 07:02 PM, Spacen Jasset wrote:
[...]
import std.math: sqrt;
import std.algorithm: map,sum,canFind;
struct Vector3{
float[3] xyz;
void normalise(){ this/=magnitude(); }
float magnitude(){ return sqrt(xyz[].map!(a=a*a).sum); }
enum scalarOps=[*,/];
enum isScalarOp(string op)=scalarOps.canFind(op);
void scalar(string op)(float scalar)if(isScalarOp!op){
foreach(ref a;xyz) mixin(`a `~op~`=scalar;`);
}
Vector3 opBinary(string op)(float scalar)if(isScalarOp!op){
Vector3 v=this;
v.scalar!op(scalar);
return v;
}
auto opOpAssign(string op)(float rhs)if(isScalarOp!op){
return mixin(`this=this `~op~` rhs`);
}
}
Thanks, that is interesting. I am curently porting, rather than
trying to rewrite anything at the moment, but I will try this out
later.
how does vibe's PrivateAccessProxy work
can someone explain a bit how the @before hooks works in detail, i mainly have problems understanding why ensureAuth in belows example refers to SampleService. as an instance: https://github.com/rejectedsoftware/vibe.d/blob/a1efc05c09135ca8aca21ccec72790ddfaca67c9/examples/web/source/app.d#L114 so how does PrivateAccessProxy work: https://github.com/rejectedsoftware/vibe.d/blob/master/source/vibe/internal/meta/funcattr.d#L225
Re: What is the D way to map a binary file to a structure?
On Saturday, 29 August 2015 at 12:56:08 UTC, cym13 wrote:
Hi,
Let's say I have a simple binary file whose structure is
well-known. Here is
an example which stores points:
struct Point {
long x;
long y;
long z;
}
struct BinFile {
uintmagicNumber; // Some identifier
ulong pointsNumber;
Point[] points; // Array of pointsNumber points.
}
What is the best way to read some file and fill a structure
with it? Would
reading the file into a void[] and then casting it to the
struct work with
things like internal struct padding?
struct Point {
long x;
long y;
long z;
}
struct BinFile {
uintmagicNumber; // Some identifier
ulong pointsNumber;
Point[] points; // Array of pointsNumber points.
this(ubyte [] buf)
{
auto f = cast(BinFile *)buf.ptr;
this = cast(BinFile)*f;
this.points =
(cast(Point*)f.points)[0..cast(uint)this.pointsNumber];
}
}
Can't chain reduce(seed, range)
Why is reduce defined as 'auto reduce(S, R)(S seed, R r)', instead of reduce(R r, S seed)? I can't chain it. Maybe provide both?
Re: Array initialization with Struct templates
On 08/30/2015 10:38 PM, Jonathan M Davis via Digitalmars-d-learn wrote:
On Monday, August 31, 2015 04:57:05 WhatMeWorry via Digitalmars-d-learn wrote:
This seemingly trivial array initialization has caused me hours
of grief.
enum Purpose { POSITIONAL, COLOR_ONLY, COLOR_AND_ALPHA,
GENERIC_TRIPLE, GENERIC_QUAD }
Purpose purpose;
struct Chameleon(T, Purpose p) // template
{
static if (is (p == POSITIONAL)) {
T x, y, z;
} else static if (is (p == COLOR_ONLY)) {
T r, g, b;
} else static if (is (p == COLOR_AND_ALPHA)) {
T r, g, b, a;
} else static if (is (p == GENERIC_TRIPLE)) {
T a, b, c;
} else static if (is (p == GENERIC_QUAD)) {
T a, b, c, d;
}
};
struct VertexData
{
Chameleon!(float, purpose.POSITIONAL) position;
Chameleon!(float, purpose.COLOR_ONLY) color;
}
alias Vert = VertexData;
VertexData[] vertices =
[
Vert(1.0, 1.0, 1.0, 0.0, 0.0, 0.0) // compiler error here
];
I keep getting:
Error: cannot implicitly convert expression (1.0) of type
double to Chameleon!(double, cast(Purpose)0)
I even tried Vert(1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f)
but it has the exact same error. Any ideas? Thanks in advance.
VertexData doesn't have a constructor that takes 6 doubles or 6 floats. It
has a compiler-generated constructor that's equivalent to
this(Chameleon!(float, purpose.POSITIONAL) position,
Chameleon!(float, purpose.COLOR_ONLY) color)
{
this.position = position;
this.color = color;
}
So, you're going to need to pass it a Chameleon!(float, purpose.POSITIONAL)
and a Chameleon!(float, purpose.COLOR_ONLY color), not 6 doubles - either
that, or you're going to need to declare a constructor for VertexData which
takes 6 doubles or floats and converts them to what's require to assign to
its member variables.
- Jonathan M Davis
Additionally, the OP uses the is expression which compares the equality
of types. However, 'Purpose p' is a value template parameter. A simple
== comparison works:
enum Purpose { POSITIONAL, COLOR_ONLY, COLOR_AND_ALPHA, GENERIC_TRIPLE,
GENERIC_QUAD }
Purpose purpose;
struct Chameleon(T, Purpose p) // template
{
static if (p == Purpose.POSITIONAL) { // <-- NOT is expression
T x, y, z;
} else static if (p == Purpose.COLOR_ONLY) {
T r, g, b;
} else static if (p == Purpose.COLOR_AND_ALPHA) {
T r, g, b, a;
} else static if (p == Purpose.GENERIC_TRIPLE) {
T a, b, c;
} else static if (p == Purpose.GENERIC_QUAD) {
T a, b, c, d;
}
};
struct VertexData
{
Chameleon!(float, purpose.POSITIONAL) position;
Chameleon!(float, purpose.COLOR_ONLY) color;
}
alias Vert = VertexData;
VertexData[] vertices =
[
Vert(Chameleon!(float, purpose.POSITIONAL)(1.0f, 1.0f, 1.0f),
Chameleon!(float, purpose.COLOR_ONLY)(0.0, 0.0, 0.0))
];
void main()
{}
Re: Can't chain reduce(seed, range)
On Monday, August 31, 2015 01:31:58 Yuxuan Shui via Digitalmars-d-learn wrote: Why is reduce defined as 'auto reduce(S, R)(S seed, R r)', instead of reduce(R r, S seed)? I can't chain it. Maybe provide both? The reasons why the seed is first are historical. It predates UFCS being added to the language, so there was no reason to put the range first when when it was added to Phobos. I believe that there have been attempts to fix it, but AFAIK, they ran into too many problems to be able to do it without breaking existing code. - Jonathan M Davis
Re: Array initialization with Struct templates
On Monday, August 31, 2015 04:57:05 WhatMeWorry via Digitalmars-d-learn wrote:
This seemingly trivial array initialization has caused me hours
of grief.
enum Purpose { POSITIONAL, COLOR_ONLY, COLOR_AND_ALPHA,
GENERIC_TRIPLE, GENERIC_QUAD }
Purpose purpose;
struct Chameleon(T, Purpose p) // template
{
static if (is (p == POSITIONAL)) {
T x, y, z;
} else static if (is (p == COLOR_ONLY)) {
T r, g, b;
} else static if (is (p == COLOR_AND_ALPHA)) {
T r, g, b, a;
} else static if (is (p == GENERIC_TRIPLE)) {
T a, b, c;
} else static if (is (p == GENERIC_QUAD)) {
T a, b, c, d;
}
};
struct VertexData
{
Chameleon!(float, purpose.POSITIONAL) position;
Chameleon!(float, purpose.COLOR_ONLY) color;
}
alias Vert = VertexData;
VertexData[] vertices =
[
Vert(1.0, 1.0, 1.0, 0.0, 0.0, 0.0) // compiler error here
];
I keep getting:
Error: cannot implicitly convert expression (1.0) of type
double to Chameleon!(double, cast(Purpose)0)
I even tried Vert(1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f)
but it has the exact same error. Any ideas? Thanks in advance.
VertexData doesn't have a constructor that takes 6 doubles or 6 floats. It
has a compiler-generated constructor that's equivalent to
this(Chameleon!(float, purpose.POSITIONAL) position,
Chameleon!(float, purpose.COLOR_ONLY) color)
{
this.position = position;
this.color = color;
}
So, you're going to need to pass it a Chameleon!(float, purpose.POSITIONAL)
and a Chameleon!(float, purpose.COLOR_ONLY color), not 6 doubles - either
that, or you're going to need to declare a constructor for VertexData which
takes 6 doubles or floats and converts them to what's require to assign to
its member variables.
- Jonathan M Davis
Array initialization with Struct templates
This seemingly trivial array initialization has caused me hours
of grief.
enum Purpose { POSITIONAL, COLOR_ONLY, COLOR_AND_ALPHA,
GENERIC_TRIPLE, GENERIC_QUAD }
Purpose purpose;
struct Chameleon(T, Purpose p) // template
{
static if (is (p == POSITIONAL)) {
T x, y, z;
} else static if (is (p == COLOR_ONLY)) {
T r, g, b;
} else static if (is (p == COLOR_AND_ALPHA)) {
T r, g, b, a;
} else static if (is (p == GENERIC_TRIPLE)) {
T a, b, c;
} else static if (is (p == GENERIC_QUAD)) {
T a, b, c, d;
}
};
struct VertexData
{
Chameleon!(float, purpose.POSITIONAL) position;
Chameleon!(float, purpose.COLOR_ONLY) color;
}
alias Vert = VertexData;
VertexData[] vertices =
[
Vert(1.0, 1.0, 1.0, 0.0, 0.0, 0.0) // compiler error here
];
I keep getting:
Error: cannot implicitly convert expression (1.0) of type
double to Chameleon!(double, cast(Purpose)0)
I even tried Vert(1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f)
but it has the exact same error. Any ideas? Thanks in advance.
