Re: Don't expect class destructors to be called at all by the GC
On Friday, 22 December 2017 at 00:09:31 UTC, Mike Franklin wrote: What condition(s) would cause a destructor for an object that is managed by the GC to potentially not be called? Good question. It's true that barring an Error, they should be called by the GC at runtime termination.
Compiler gets confused with ambiguity when `int` matches both `real` and `float`.
The following expression: import std.math : sqrt; sqrt(400); produces the following compiler error: std.math.sqrt called with argument types (int) matches both: /usr/include/dmd/phobos/std/math.d(1592,7): std.math.sqrt(float x) and: /usr/include/dmd/phobos/std/math.d(1598,6): std.math.sqrt(real x) Shouldn't it just pick one according to some defined rules?
Re: why ushort alias casted to int?
On Friday, 22 December 2017 at 10:42:28 UTC, crimaniak wrote: Hm, really. ok, I will use the explicit cast, but I don't like it. It's because the C programming language has similar integer promotion rules. That doesn't make it any more convenient if you weren't expecting it but that is the reason behind it.
Re: why ushort alias casted to int?
crimaniak wrote: Both operands are the same type, so as I understand casting to longest type is not needed at all, and longest type here is ushort in any case. What am I doing wrong? it is hidden in specs: all types shorter than int are promoted to int before doing any math.
Re: why ushort alias casted to int?
On Friday, 22 December 2017 at 10:18:52 UTC, ketmar wrote: crimaniak wrote: Both operands are the same type, so as I understand casting to longest type is not needed at all, and longest type here is ushort in any case. What am I doing wrong? it is hidden in specs: all types shorter than int are promoted to int before doing any math. Hm, really. ok, I will use the explicit cast, but I don't like it.
why ushort alias casted to int?
My code:
alias MemSize = ushort;
struct MemRegion
{
MemSize start;
MemSize length;
@property MemSize end() const { return start+length; }
}
Error: cannot implicitly convert expression `cast(int)this.start
+ cast(int)this.length` of type `int` to `ushort`
Both operands are the same type, so as I understand casting to
longest type is not needed at all, and longest type here is
ushort in any case. What am I doing wrong?
Does LDC support profiling at all?
DMD can use -profile and -profile=gc. But I tried for HOURS to find the equivalent for LDC and came up with only profile-guided optimization--which I don't believe I want. Yet, if we can get PGO... where's the PROFILE itself it's using to make those decisions! :) Thanks.
Re: std way to remove multiple indices from an array at once
On Thursday, 21 December 2017 at 15:59:44 UTC, Steven Schveighoffer wrote: Here's a similar solution with an actual range: https://run.dlang.io/is/gR3CjF Note, all done lazily. However, the indices must be sorted/unique. -Steve Noice! :D
Re: why ushort alias casted to int?
On Friday, 22 December 2017 at 10:14:48 UTC, crimaniak wrote:
My code:
alias MemSize = ushort;
struct MemRegion
{
MemSize start;
MemSize length;
@property MemSize end() const { return start+length; }
}
Error: cannot implicitly convert expression
`cast(int)this.start + cast(int)this.length` of type `int` to
`ushort`
Both operands are the same type, so as I understand casting to
longest type is not needed at all, and longest type here is
ushort in any case. What am I doing wrong?
@property MemSize end() const { return cast(int)(start+length); }
The rule of int promotion of smaller types comes from C as they
said. There are 2 reason to do it that way. int is supposed in C
to be the natural arithmetic type of the CPU it runs on, i.e. the
default size the processor has the least difficulties to handle.
The second reason is that it allows to detect easily without much
hassle if the result of the operation is in range or not. When
doing arithmetic with small integer types, it is easy that the
result overflows. It is not that easy to define portably this
overflow behaviour. On some cpus it would require extra
instructions. D has inherited this behaviour so that copied
arithmetic code coming from C behaves in the same way.
@property MemSize end() const
{
MemSize result = start+length;
assert(result <= MemSize.max);
return cast(int)result;
}
with overflow arithmetic this code is not possible (as is if
MemSize was uint or ulong).
Re: Version Cygwin
On Friday, 22 December 2017 at 03:24:15 UTC, rikki cattermole wrote: You are not using a Cygwin build. It doesn't matter who calls a process, it doesn't change the version's by itself. As far as I know, nobody supports Cygwin like this. I see, thank you.
Re: GC in D and synadard library.
See also how dplug is implemented https://forum.dlang.org/post/hbmbztydvyfwemfne...@forum.dlang.org
alias to struct method
How can I create a alias to a struct method?
struct S {
string doSomething(int n) { return ""; }
}
I'd like to do something like this (imaginary code):
alias doSomething = S.doSomething;
then call it by doSomething(3)
I got the following error from this code:
Error: need 'this' for 'gen' of type 'string(int n)'
So I tried create a instance:
alias doSomething = S().doSomething;
Changes the error to:
app.d(96): Error: function declaration without return type.
(Note that > constructors are always named this)
app.d(96): Error: semicolon expected to close alias declaration
Re: Does LDC support profiling at all?
On Friday, 22 December 2017 at 09:52:26 UTC, Chris Katko wrote: DMD can use -profile and -profile=gc. But I tried for HOURS to find the equivalent for LDC and came up with only profile-guided optimization--which I don't believe I want. Yet, if we can get PGO... where's the PROFILE itself it's using to make those decisions! :) Thanks. Is -fprofile-instr-generate= what you're looking for?
Re: Converting member variables to strings with using reflection from base class
On Fri, Dec 22, 2017 at 09:13:31PM +, kerdemdemir via Digitalmars-d-learn
wrote:
> I want to make a logging function for member variables by using reflection.
[...]
> class B
> {
> void Log()
> {
> auto a = [__traits(derivedMembers, D)];
> foreach(memberName; a) {
> // Somehow write only member variables with their names
> // Result should be : a = 4.0, b = 3.0
Try this:
import std.traits : FieldNameTuple;
foreach (memberName; FieldNameTuple!B) {
writefln("%s = %s", memberName, mixin("this." ~ memberName));
}
T
--
People walk. Computers run.
How to I get the dub package version that I want...
I can compile the derelict-fmod example with
dub.json
...
"dependencies": {
"derelict-util": ">=1.9.1"
...
and dub.selections.json
...
"versions": {
"derelict-util": "2.1.0"
...
dub run
Fetching derelict-util 2.1.0 (getting selected version)...
Performing "debug" build using ldc2 for x86_64.
derelict-util 2.1.0: building configuration "library"...
==
In my project, I use SDL
dub.sdl
...
dependency "derelict-util" version=">=1.9.1"
...
dub upgrade
Upgrading project in /home/generic/Delivery/apps/06_03_09_audio
Fetching derelict-util 2.0.6 (getting selected version)...
which is a higher version but no cigar. So I try brute force with
dub.sdl
...
dependency "derelict-util" version="==2.1.0"
...
but dub upgrade returns:
Upgrading project in /home/generic/Delivery/apps/06_03_09_audio
Root package 06_03_09_audio reference derelict-util 2.1.0 cannot
be satisfied.
There is definitely a 2.1.0 derelict-util package with a time
stamp of 2016-Sep-05
So what am I doing wrong?
Converting member variables to strings with using reflection from base class
I want to make a logging function for member variables by using
reflection.
import std.stdio;
class D : B
{
override void foo() {
a = 4.0;
b = 3.0;
}
double a;
double b;
}
class B
{
void Log()
{
auto a = [__traits(derivedMembers, D)];
foreach(memberName; a) {
// Somehow write only member variables with their
names
// Result should be : a = 4.0, b = 3.0
}
}
void foo()
{
}
}
void main()
{
auto b = new D;
b.Log();
}
As I wrote in the comments I want to see member variable's name
and its value.
What is the best way to achieve that?
Erdem
Parsing string to octal(for umask) at runtime?
Hi. Struggling to figure this out. At the bottom of this page: https://dlang.org/library/std/conv/octal.html is a vague reference to using parse. However, when I use what I would assume to be correct based on this: https://dlang.org/phobos/std_conv.html#.parse.3 and the fact that in the octal page it says octal is also a enum, I see no reason this syntax shouldn't work: import std.conv; umaskVal = parse!octal(data.umask); Yet I get an error saying the compiler cannot deduce which overload of parse to use... How do I do this parse? Am I going about this the wrong way? Is there a better way to parse a string as a normal base8 ushort?
Re: Parsing string to octal(for umask) at runtime?
On Friday, 22 December 2017 at 21:36:20 UTC, Ryan David Sheasby wrote: Hi. Struggling to figure this out. At the bottom of this page: https://dlang.org/library/std/conv/octal.html is a vague reference to using parse. However, when I use what I would assume to be correct based on this: https://dlang.org/phobos/std_conv.html#.parse.3 and the fact that in the octal page it says octal is also a enum, I see no reason this syntax shouldn't work: import std.conv; umaskVal = parse!octal(data.umask); Yet I get an error saying the compiler cannot deduce which overload of parse to use... How do I do this parse? Am I going about this the wrong way? Is there a better way to parse a string as a normal base8 ushort? Nevermind. I've just figured it out from this forum post :-) http://forum.dlang.org/thread/nbvdebjxodabukfbe...@forum.dlang.org All I needed to do was: umaskVal = parse!ushort(data.umask, 8);
Re: alias to struct method
On 12/22/2017 09:53 AM, Marc wrote:
> How can I create a alias to a struct method?
>
>> struct S {
>> string doSomething(int n) { return ""; }
>> }
>
> I'd like to do something like this (imaginary code):
>
> alias doSomething = S.doSomething;
>
> then call it by doSomething(3)
That can't work because there is no S object to call doSomething on. One
way is to use a delegate:
struct S {
string doSomething(int n) { return ""; }
}
void main() {
S s;
auto d = (int n) { s.doSomething(n); };
d(3);
}
Ali
Re: alias to struct method
On Friday, 22 December 2017 at 17:53:34 UTC, Marc wrote:
How can I create a alias to a struct method?
struct S {
string doSomething(int n) { return ""; }
}
I'd like to do something like this (imaginary code):
alias doSomething = S.doSomething;
then call it by doSomething(3)
I got the following error from this code:
Error: need 'this' for 'gen' of type 'string(int n)'
So I tried create a instance:
alias doSomething = S().doSomething;
Changes the error to:
app.d(96): Error: function declaration without return type.
(Note that > constructors are always named this)
app.d(96): Error: semicolon expected to close alias declaration
it is also possible with getMember trait but why don't you just
mark that method as static?
Re: Converting member variables to strings with using reflection from base class
On Friday, 22 December 2017 at 22:09:05 UTC, H. S. Teoh wrote:
On Fri, Dec 22, 2017 at 09:13:31PM +, kerdemdemir via
Digitalmars-d-learn wrote:
I want to make a logging function for member variables by
using reflection.
[...]
class B
{
void Log()
{
auto a = [__traits(derivedMembers, D)];
foreach(memberName; a) {
// Somehow write only member variables with their
names
// Result should be : a = 4.0, b = 3.0
Try this:
import std.traits : FieldNameTuple;
foreach (memberName; FieldNameTuple!B) {
writefln("%s = %s", memberName, mixin("this." ~ memberName));
}
T
and then turn it into a LoggerMixin with a mixin template and
re-use it any time you want.
import std.stdio : writeln, writefln;
import std.traits : FieldNameTuple;
mixin template LoggerMixin() {
void Log() {
foreach (memberName; FieldNameTuple!(typeof(this))) {
writefln("%s = %s", memberName, mixin("this." ~
memberName));
}
}
}
struct S {
int x;
bool y;
double z;
mixin LoggerMixin;
}
void main() {
S s1 = S(int.min, true, );
S s2 = S(int.max, false, );
s1.Log();
s2.Log();
}
Re: One liner for creating an array filled by a factory method
On Thursday, 21 December 2017 at 21:11:58 UTC, Steven
Schveighoffer wrote:
On 12/21/17 4:00 PM, kerdemdemir wrote:
I have a case like :
http://rextester.com/NFS28102
I have a factory method, I am creating some instances given
some enums.
My question is about :
void PushIntoVector( BaseEnum[] baseEnumList )
{
Base[] baseList;
foreach ( tempEnum; baseEnumList )
{
baseList ~= Factory(tempEnum);
}
}
I don't want to use "foreach" loop. Is there any cool std
function that I can call ?
Something like baseEnumList.CoolStdFunc!( a=> Factory(a)
)(baseList);
https://dlang.org/phobos/std_algorithm_iteration.html#map
-Steve
so basically it becomes:
Base[] baseList = baseEnumList.map!(el => Factory(el));
there's also a parallel version of map [0] if you ever need to
map the list concurrently.
[0] https://dlang.org/phobos/std_parallelism.html#.TaskPool.map
Re: Don't expect class destructors to be called at all by the GC
On Thursday, 21 December 2017 at 18:45:27 UTC, Adam D. Ruppe wrote: On Thursday, 21 December 2017 at 18:20:19 UTC, H. S. Teoh wrote: When the scoped destruction of structs isn't an option, RefCounted!T seems to be a less evil alternative than an unreliable class dtor. :-/ Alas, RefCounted doesn't work well with inheritance... Though, what you could do is make the refcounted owners and borrow the actual reference later. i really wonder how Objective-C and Swift is pulling this off.
Re: Don't expect class destructors to be called at all by the GC
On Friday, 22 December 2017 at 23:34:55 UTC, Mengu wrote: i really wonder how Objective-C and Swift is pulling this off. It isn't a fundamental problem, D just can't express it in the existing language (heck, even D, as defined, could do it, the implementation just isn't there.)
