Define methods using templates
Hello, I'm trying to use templates to define several methods
(property setters) within a class to avoid some code duplication.
Here is an attempt:
class Camera
{
private:
Vector4 m_pos;
float m_fov, m_ratio, m_near, m_far;
bool m_matrixCalculated;
public:
void SetProperty(Tin, alias Field)(ref Tin param) @property
pure @safe
{
Field = param;
m_matrixCalculated = false;
}
alias pos = SetProperty!(float[], m_pos);
alias pos = SetProperty!(Vector4, m_pos);
alias ratio = SetProperty!(float, m_ratio);
alias near = SetProperty!(float, m_near);
alias far = SetProperty!(float, m_far);
}
I get this kind of compilation error:
Error: template instance SetProperty!(float[], m_pos) cannot use
local 'm_pos' as parameter to non-global template
SetProperty(Tin, alias Field)(ref Tin param)
I don't understand why that error occurs.
And I cannot find any elegant solutions (even with mixin's) to
declare a template and then instantiate it in a single line to
define the methods I want.
Does any of you have an idea?
Thanks
Re: Define methods using templates
On 12/30/14 8:17 AM, Claude wrote:
Hello, I'm trying to use templates to define several methods (property
setters) within a class to avoid some code duplication.
Here is an attempt:
class Camera
{
private:
Vector4 m_pos;
float m_fov, m_ratio, m_near, m_far;
bool m_matrixCalculated;
public:
void SetProperty(Tin, alias Field)(ref Tin param) @property pure @safe
{
Field = param;
m_matrixCalculated = false;
}
alias pos = SetProperty!(float[], m_pos);
alias pos = SetProperty!(Vector4, m_pos);
alias ratio = SetProperty!(float, m_ratio);
alias near = SetProperty!(float, m_near);
alias far = SetProperty!(float, m_far);
}
I get this kind of compilation error:
Error: template instance SetProperty!(float[], m_pos) cannot use local
'm_pos' as parameter to non-global template SetProperty(Tin, alias
Field)(ref Tin param)
I don't understand why that error occurs.
I think it has to do with the fact that when you are defining the
aliases, m_pos for example, is an *instance* member so requires an
instance to get an alias.
What you are probably better off doing is:
void SetProperty(Tin, string Field)(ref Tin param) @property pure @safe
{
mixin(Field ~ = param;);
m_matrixCalculated = false;
}
alias pos = SetProperty!(float[], m_pos);
I would also put some strict template constraints on the Field string
too, because one abuse SetProperty pretty easily there.
-Steve
Re: Define methods using templates
On 12/30/14 8:48 AM, Steven Schveighoffer wrote:
I think it has to do with the fact that when you are defining the
aliases, m_pos for example, is an *instance* member so requires an
instance to get an alias.
What you are probably better off doing is:
void SetProperty(Tin, string Field)(ref Tin param) @property pure @safe
{
mixin(Field ~ = param;);
m_matrixCalculated = false;
}
alias pos = SetProperty!(float[], m_pos);
I would also put some strict template constraints on the Field string
too, because one abuse SetProperty pretty easily there.
A possibly more elegant solution, use opDispatch:
void opDispatch(string Field, Tin)(ref Tin param) @property pure @safe
if(Field == pos || Field == ratio || ...)
{
mixin(m_ ~ Field ~ = param;);
m_matrixCalculated = false;
}
Not sure if opDispatch works as a @property this way...
-Steve
Re: Define methods using templates
V Tue, 30 Dec 2014 13:17:08 +
Claude via Digitalmars-d-learn digitalmars-d-learn@puremagic.com
napsáno:
Hello, I'm trying to use templates to define several methods
(property setters) within a class to avoid some code duplication.
Here is an attempt:
class Camera
{
private:
Vector4 m_pos;
float m_fov, m_ratio, m_near, m_far;
bool m_matrixCalculated;
public:
void SetProperty(Tin, alias Field)(ref Tin param) @property
pure @safe
{
Field = param;
m_matrixCalculated = false;
}
alias pos = SetProperty!(float[], m_pos);
alias pos = SetProperty!(Vector4, m_pos);
alias ratio = SetProperty!(float, m_ratio);
alias near = SetProperty!(float, m_near);
alias far = SetProperty!(float, m_far);
}
I get this kind of compilation error:
Error: template instance SetProperty!(float[], m_pos) cannot use
local 'm_pos' as parameter to non-global template
SetProperty(Tin, alias Field)(ref Tin param)
I don't understand why that error occurs.
And I cannot find any elegant solutions (even with mixin's) to
declare a template and then instantiate it in a single line to
define the methods I want.
Does any of you have an idea?
Thanks
class Camera
{
private:
int m_pos;
float m_fov, m_ratio, m_near, m_far;
bool m_matrixCalculated;
public:
mixin template opAssign(alias Field) {
void opAssign(Tin)(auto ref Tin param) @property pure @safe
{
Field = param;
m_matrixCalculated = false;
}
}
mixin opAssign!(m_pos) pos;
mixin opAssign!(m_fov) fov;
mixin opAssign!(m_ratio) ratio;
mixin opAssign!(m_near) near;
mixin opAssign!(m_far) far;
}
void main() {
Camera cam = new Camera();
cam.fov = 1.0;
stdin.readln;
}
Do you have any idea about deleting exe's symbol table on windows building by DMD or LDC2 64 bit?
Do you have any idea about deleting exe's symbol table on windows? I know mingw for win32 is ok. do you have any other idea about building by DMD or or LDC2 64 bit? Thank you.
Re: Define methods using templates
Thanks Steven and Daniel for your explanations.
mixin template opAssign(alias Field) {
void opAssign(Tin)(auto ref Tin param) @property pure
@safe
{
Field = param;
m_matrixCalculated = false;
}
}
mixin opAssign!(m_pos) pos;
I tested both the string mixin and opAssign implementations,
and they work like a charm.
I would have never thought of using both @property and
opAssign, but it looks like a secure way of doing it for the
compilation fails nicely if I type a wrong field in.
src/camera.d(58): Error: undefined identifier m_os, did you mean
variable m_pos?
Is it possible to use an UDA to generate a struct inside a class ?
I have a struct used to describe a property[1].
Its standard usage is represented in this simple example:
|class Bar {
|private uint fField0;
|private izPropDescriptor!uint descrField0;
|this() {
|descrField0.define(field0, field0, field0);
|}
|public void field0(uint aValue) {fField0 = aValue;}
|public uint field0(){return fField0;}
|}
The descriptor is used by a property binding system or a
serializer.
The problem is that declaring a property descriptor is **very**
repetitive.
I've always wanted to find a way to generate a descriptor
automatically,
and finally today, while reading some random things on GH, I've
found that
the annotation system used in HibernateD[2] could be used. So far
I didnt get the point of UDA and never used them.
So I've created a basic UDA but, and then ? Can a descriptor be
created using my attribute ? How ?
|struct Setter {
|const char[] propertyName;
|}
|struct Getter {
|const char[] propertyName;
|}
|class Foo {
|private uint fField0;
|public @Setter(field0) void field0(uint aValue) {
|fField0 = aValue;
|}
|public @Getter(field0) uint field0(){
|return fField0;
|}
|}
[1]:https://github.com/BBasile/Iz/blob/master/import/iz/properties.d#L27
[2]:https://github.com/buggins/hibernated/blob/master/source/hibernated/annotations.d#L15
Re: Is it possible to use an UDA to generate a struct inside a class ?
On 12/30/2014 09:42 AM, Basile Burg wrote:
Can a descriptor be created using my attribute ? How ?
Here is a quick and dirty solution:
import std.string;
struct PropertyDescriptor
{
string type;
string name;
string memberName() @property const
{
return name ~ _;
}
string definition() @property const
{
return format(%s %s;, type, memberName);
}
string getter() @property const
{
return format(%s %s() @property const { return %s; },
type, name, memberName);
}
string setter() @property const
{
return format(void %s(%s value) @property { %s = value; },
name, type, memberName);
}
}
unittest
{
const descr = PropertyDescriptor(int, foo);
assert(descr.memberName == foo_);
assert(descr.definition == q{int foo_;});
assert(descr.getter == q{int foo() @property const { return foo_; }});
assert(descr.setter ==
q{void foo(int value) @property { foo_ = value; }});
}
struct Property
{
PropertyDescriptor[] properties;
string propertyCode() @property const
{
string result;
foreach (property; properties) {
result ~= property.definition ~ property.getter ~
property.setter;
}
return result;
}
}
string propertyInjections(T)()
{
string result;
foreach (attr; __traits(getAttributes, T)) {
static if (is (typeof(attr) == Property)) {
result ~= attr.propertyCode;
}
}
return result;
}
@Property([ PropertyDescriptor(int, i),
PropertyDescriptor(double, d) ])
class C
{
mixin (propertyInjections!C);
}
void main()
{
auto c = new C();
c.i = 42;
assert(c.i == 42);
}
Ali
Re: Define methods using templates
On 12/30/2014 05:17 AM, Claude wrote: use templates to define several methods (property setters) within a class to avoid some code duplication. I just saw this post, which is essentially the same question as Basile Burg's. I hope that a college (in France?) is teaching D and that this is a homework assignment. Cool stuff! :) Ali
Re: Is it possible to use an UDA to generate a struct inside a class ?
On Tuesday, 30 December 2014 at 19:05:23 UTC, Ali Çehreli wrote:
On 12/30/2014 09:42 AM, Basile Burg wrote:
Can a descriptor be created using my attribute ? How ?
Here is a quick and dirty solution:
import std.string;
struct PropertyDescriptor
{
string type;
string name;
string memberName() @property const
{
return name ~ _;
}
string definition() @property const
{
return format(%s %s;, type, memberName);
}
string getter() @property const
{
return format(%s %s() @property const { return %s; },
type, name, memberName);
}
string setter() @property const
{
return format(void %s(%s value) @property { %s =
value; },
name, type, memberName);
}
}
unittest
{
const descr = PropertyDescriptor(int, foo);
assert(descr.memberName == foo_);
assert(descr.definition == q{int foo_;});
assert(descr.getter == q{int foo() @property const { return
foo_; }});
assert(descr.setter ==
q{void foo(int value) @property { foo_ = value; }});
}
struct Property
{
PropertyDescriptor[] properties;
string propertyCode() @property const
{
string result;
foreach (property; properties) {
result ~= property.definition ~ property.getter ~
property.setter;
}
return result;
}
}
string propertyInjections(T)()
{
string result;
foreach (attr; __traits(getAttributes, T)) {
static if (is (typeof(attr) == Property)) {
result ~= attr.propertyCode;
}
}
return result;
}
@Property([ PropertyDescriptor(int, i),
PropertyDescriptor(double, d) ])
class C
{
mixin (propertyInjections!C);
}
void main()
{
auto c = new C();
c.i = 42;
assert(c.i == 42);
}
Ali
Ok, thx. I see the trick:
mixin (propertyInjections!C);
Introspection inside each class. I don't find this solution ugly
btw. I think there is no other way to do this.
Idea/request: If you have a DUB project, add a code.dlang.org badge to README
A few weeks/months ago someone here mentioned that it'd be good if DUB projects linked to code.dlang.org to help anyone who runs into such a project quickly discover other D projects. MAny GitHub projects have badges/shields on top of their READMEs - little image strips showing things like continuous integration status, code coverage, etc. There's also a service generating these: shields.io I generated a simple listed at| code.dlang.org shield, and added it to my project READMEs as a link pointing to code.dlang.org for example, see D:YAML README: https://github.com/kiith-sa/D-YAML You can do the same by either linking to or downloading the shield: https://img.shields.io/badge/listed%20at-code.dlang.org-red.png (used red... because mars) and putting the image (whether as a link to shields.io or your own copy) into your README. It's not likely to be a huge improvement, but I expect it *can* help people notice more D projects and it's trivial to do.
Re: Idea/request: If you have a DUB project, add a code.dlang.org badge to README
On Tuesday, 30 December 2014 at 21:12:38 UTC, Kiith-Sa wrote: A few weeks/months ago someone here mentioned that it'd be good if DUB projects linked to code.dlang.org to help anyone who runs into such a project quickly discover other D projects. MAny GitHub projects have badges/shields on top of their READMEs - little image strips showing things like continuous integration status, code coverage, etc. There's also a service generating these: shields.io I generated a simple listed at| code.dlang.org shield, and added it to my project READMEs as a link pointing to code.dlang.org for example, see D:YAML README: https://github.com/kiith-sa/D-YAML You can do the same by either linking to or downloading the shield: https://img.shields.io/badge/listed%20at-code.dlang.org-red.png (used red... because mars) and putting the image (whether as a link to shields.io or your own copy) into your README. It's not likely to be a huge improvement, but I expect it *can* help people notice more D projects and it's trivial to do. red is connoted negative/agressive, I think blue would be better. Or maybe yellow-mustard for those who have doubtful tastes...
Re: Idea/request: If you have a DUB project, add a code.dlang.org badge to README
On Tuesday, 30 December 2014 at 21:19:52 UTC, jklp wrote: On Tuesday, 30 December 2014 at 21:12:38 UTC, Kiith-Sa wrote: A few weeks/months ago someone here mentioned that it'd be good if DUB projects linked to code.dlang.org to help anyone who runs into such a project quickly discover other D projects. MAny GitHub projects have badges/shields on top of their READMEs - little image strips showing things like continuous integration status, code coverage, etc. There's also a service generating these: shields.io I generated a simple listed at| code.dlang.org shield, and added it to my project READMEs as a link pointing to code.dlang.org for example, see D:YAML README: https://github.com/kiith-sa/D-YAML You can do the same by either linking to or downloading the shield: https://img.shields.io/badge/listed%20at-code.dlang.org-red.png (used red... because mars) and putting the image (whether as a link to shields.io or your own copy) into your README. It's not likely to be a huge improvement, but I expect it *can* help people notice more D projects and it's trivial to do. red is connoted negative/agressive, I think blue would be better. Or maybe yellow-mustard for those who have doubtful tastes... If you want blue, just replace red with blue. I used red because it's the color of the D logo, site and the color of Mars (as D was originally called Mars and lot of D things are named after Mars, e.g. Phobos/Deimos etc.)
Re: Idea/request: If you have a DUB project, add a code.dlang.org badge to README
On Tuesday, 30 December 2014 at 21:19:52 UTC, jklp wrote: On Tuesday, 30 December 2014 at 21:12:38 UTC, Kiith-Sa wrote: A few weeks/months ago someone here mentioned that it'd be good if DUB projects linked to code.dlang.org to help anyone who runs into such a project quickly discover other D projects. MAny GitHub projects have badges/shields on top of their READMEs - little image strips showing things like continuous integration status, code coverage, etc. There's also a service generating these: shields.io I generated a simple listed at| code.dlang.org shield, and added it to my project READMEs as a link pointing to code.dlang.org for example, see D:YAML README: https://github.com/kiith-sa/D-YAML You can do the same by either linking to or downloading the shield: https://img.shields.io/badge/listed%20at-code.dlang.org-red.png (used red... because mars) and putting the image (whether as a link to shields.io or your own copy) into your README. It's not likely to be a huge improvement, but I expect it *can* help people notice more D projects and it's trivial to do. red is connoted negative/agressive, I think blue would be better. Or maybe yellow-mustard for those who have doubtful tastes... aand what I was supposed to post (I didn't itend to put this in D.learn): http://forum.dlang.org/thread/tbspahcinalabopfb...@forum.dlang.org#post-tbspahcinalabopfbxey:40forum.dlang.org
Re: Idea/request: If you have a DUB project, add a code.dlang.org badge to README
On Tuesday, 30 December 2014 at 21:23:53 UTC, Kiith-Sa wrote: On Tuesday, 30 December 2014 at 21:19:52 UTC, jklp wrote: On Tuesday, 30 December 2014 at 21:12:38 UTC, Kiith-Sa wrote: A few weeks/months ago someone here mentioned that it'd be good if DUB projects linked to code.dlang.org to help anyone who runs into such a project quickly discover other D projects. MAny GitHub projects have badges/shields on top of their READMEs - little image strips showing things like continuous integration status, code coverage, etc. There's also a service generating these: shields.io I generated a simple listed at| code.dlang.org shield, and added it to my project READMEs as a link pointing to code.dlang.org for example, see D:YAML README: https://github.com/kiith-sa/D-YAML You can do the same by either linking to or downloading the shield: https://img.shields.io/badge/listed%20at-code.dlang.org-red.png (used red... because mars) and putting the image (whether as a link to shields.io or your own copy) into your README. It's not likely to be a huge improvement, but I expect it *can* help people notice more D projects and it's trivial to do. red is connoted negative/agressive, I think blue would be better. Or maybe yellow-mustard for those who have doubtful tastes... If you want blue, just replace red with blue. I used red because it's the color of the D logo, site and the color of Mars (as D was originally called Mars and lot of D things are named after Mars, e.g. Phobos/Deimos etc.) Sorry it was a trivial and useless answer. forgot that this board is excusively serious.
Re: Fastest Way to Append Multiple Elements to an Array
On Saturday, 27 December 2014 at 07:34:43 UTC, Tobias Pankrath wrote: On Friday, 26 December 2014 at 16:31:48 UTC, Nordlöw wrote: On Friday, 26 December 2014 at 16:29:56 UTC, Nordlöw wrote: See my update at https://github.com/nordlow/justd/blob/master/algorithm_ex.d#L1602 which tries to merge all the ideas into one adapting algorithm :) Destroy! BTW: writeln(estimateLength([1,2,3],[1,2,3])); If appending to an int[] this must print 6, if appending to an int[][] it should print 2. Do you have a suitable proposal for a CT-expression that checks if an argument of type E to estimateLength() will be treated as T[] in the append? My current suggestion is isArray!A is(T == ElementType!(A)) hasLength!A in use at https://github.com/nordlow/justd/blob/master/algorithm_ex.d#L1602 with the hope of being compatible with static arrays. However uncommenting https://github.com/nordlow/justd/blob/master/algorithm_ex.d#L1680 gives compilation error as algorithm_ex.d(1658,20): Error: template std.array.Appender!(int[]).Appender.put cannot deduce function from argument types !()(int[3]), candidates are: /home/per/opt/x86_64-unknown-linux-gnu/dmd/linux/bin64/src/phobos/std/array.d(2518,10): std.array.Appender!(int[]).Appender.put(U)(U item) if (canPutItem!U) /home/per/opt/x86_64-unknown-linux-gnu/dmd/linux/bin64/src/phobos/std/array.d(2554,10): std.array.Appender!(int[]).Appender.put(Range)(Range items) if (canPutConstRange!Range) /home/per/opt/x86_64-unknown-linux-gnu/dmd/linux/bin64/src/phobos/std/array.d(2563,10): std.array.Appender!(int[]).Appender.put(Range)(Range items) if (canPutRange!Range) algorithm_ex.d(1658,20): Error: template std.array.Appender!(int[]).Appender.put cannot deduce function from argument types !()(int[3]), candidates are: /home/per/opt/x86_64-unknown-linux-gnu/dmd/linux/bin64/src/phobos/std/array.d(2518,10): std.array.Appender!(int[]).Appender.put(U)(U item) if (canPutItem!U) /home/per/opt/x86_64-unknown-linux-gnu/dmd/linux/bin64/src/phobos/std/array.d(2554,10): std.array.Appender!(int[]).Appender.put(Range)(Range items) if (canPutConstRange!Range) /home/per/opt/x86_64-unknown-linux-gnu/dmd/linux/bin64/src/phobos/std/array.d(2563,10): std.array.Appender!(int[]).Appender.put(Range)(Range items) if (canPutRange!Range) algorithm_ex.d(1681,16): Error: template instance algorithm_ex.append!(int, int[3], int[3]) error instantiating Comint exited abnormally with code 1 at Tue Dec 30 23:55:33 Isn't appender compatible with static arrays?
Re: Fastest Way to Append Multiple Elements to an Array
On Friday, 26 December 2014 at 16:31:48 UTC, Nordlöw wrote: On Friday, 26 December 2014 at 16:29:56 UTC, Nordlöw wrote: See my update at https://github.com/nordlow/justd/blob/master/algorithm_ex.d#L1602 which tries to merge all the ideas into one adapting algorithm :) Destroy! BTW: 1. Is is relevant to extend `append` to data being a non-Random-Access range? 2. I guess a corresponding `prepend` is motivated aswell, right? Append and Prepend would be very useful additions to Phobos it's quite surprising there not already there? In any case would love to see some pull requests :)
getting current DateTime
How do you get the current DateTime? Why doesn't DateTime have DateTime.now?
Re: getting current DateTime
On Wednesday, 31 December 2014 at 06:03:06 UTC, bitwise wrote:
How do you get the current DateTime?
Why doesn't DateTime have DateTime.now?
import std.stdio;
import std.datetime;
void main()
{
writeln(Clock.currTime);
}
Frank
Re: getting current DateTime
On Wed, 31 Dec 2014 06:03:04 + bitwise via Digitalmars-d-learn digitalmars-d-learn@puremagic.com wrote: How do you get the current DateTime? Why doesn't DateTime have DateTime.now? but it has! ;-) auto now = cast(DateTime)Clock.currTime; signature.asc Description: PGP signature
Re: getting current DateTime
On Wednesday, 31 December 2014 at 06:31:13 UTC, ketmar via Digitalmars-d-learn wrote: On Wed, 31 Dec 2014 06:03:04 + bitwise via Digitalmars-d-learn digitalmars-d-learn@puremagic.com wrote: How do you get the current DateTime? Why doesn't DateTime have DateTime.now? but it has! ;-) auto now = cast(DateTime)Clock.currTime; Ah! indeed it does. It would be nice if that cast was made implicit though. Thanks =D
Re: getting current DateTime
It would be nice if that cast was made implicit though. Just realizing now that DateTime doesn't have sub-second accuracy =/
