Re: dcollections ArrayList pb with mixin template
On Thu, 01 Jul 2010 18:26:06 -0400, bearophile bearophileh...@lycos.com wrote: Steven Schveighoffer: I think a member initializer has to be a constant expression, like int i = 1. Anything else has to be done in the constructor. There are the static constructors too, for modules, structs, classes. static constructors don't help initialize member variables. -Steve
dcollections ArrayList pb with mixin template
Hi, I have a problem with a mixin template. More exact with an
Arraylist!T within a mixin template.
Given.
void main() {
auto p = new Person(Hans, 32);
p ~= new Person(Steve, 40);
p ~= new Person(Bjoern, 101);
}
class Person {
private string _name;
private uint _age;
mixin TLinkList;
this(string name, uint age) {
this._name = name;
this._age = age;
}
}
mixin template TLinkList() {
alias typeof(this) T;
alias ArrayList!T TList;
T[] pa;
auto pl = new TList(pa); // This does not work !
void opCatAssign(T v) {
pa ~= v;
}
}
Error: non-constant expression new ArrayList(pa)main.d
Ideas ?
Thanks Bjoern
Re: dcollections ArrayList pb with mixin template
On Thu, 01 Jul 2010 15:36:53 -0400, BLS windev...@hotmail.de wrote:
Hi, I have a problem with a mixin template. More exact with an
Arraylist!T within a mixin template.
Given.
void main() {
auto p = new Person(Hans, 32);
p ~= new Person(Steve, 40);
p ~= new Person(Bjoern, 101);
}
class Person {
private string _name;
private uint _age;
mixin TLinkList;
this(string name, uint age) {
this._name = name;
this._age = age;
}
}
mixin template TLinkList() {
alias typeof(this) T;
alias ArrayList!T TList;
T[] pa;
auto pl = new TList(pa); // This does not work !
void opCatAssign(T v) {
pa ~= v;
}
}
Error: non-constant expression new ArrayList(pa)main.d
Ideas ?
Thanks Bjoern
I'm thinking it has to do with you trying to create a member with that
line.
I think a member initializer has to be a constant expression, like int i =
1. Anything else has to be done in the constructor. This kinda sucks,
because you can't initialize members with their defaults where you declare
them, but it's the way D works.
-Steve
Re: dcollections ArrayList pb with mixin template
On 01/07/2010 22:59, Steven Schveighoffer wrote:
On Thu, 01 Jul 2010 15:36:53 -0400, BLS windev...@hotmail.de wrote:
Hi, I have a problem with a mixin template. More exact with an
Arraylist!T within a mixin template.
Given.
void main() {
auto p = new Person(Hans, 32);
p ~= new Person(Steve, 40);
p ~= new Person(Bjoern, 101);
}
class Person {
private string _name;
private uint _age;
mixin TLinkList;
this(string name, uint age) {
this._name = name;
this._age = age;
}
}
mixin template TLinkList() {
alias typeof(this) T;
alias ArrayList!T TList;
T[] pa;
auto pl = new TList(pa); // This does not work !
void opCatAssign(T v) {
pa ~= v;
}
}
Error: non-constant expression new ArrayList(pa) main.d
Ideas ?
Thanks Bjoern
I'm thinking it has to do with you trying to create a member with that
line.
I think a member initializer has to be a constant expression, like int i
= 1. Anything else has to be done in the constructor. This kinda sucks,
because you can't initialize members with their defaults where you
declare them, but it's the way D works.
-Steve
Thanks for the feedback Steve.
IMHO it should work.. One reason is that C.E. Miller has created a
Circularly-linked list module, containing a portable linked list
template mixin. Indeed Christophers implementation is different in that
the LinkList is part of the mixin template...
http://www.dprogramming.com/list.php
2) Commenting the auto pl = new TList() line out makes the snippet work.
mixin template TLinkList() {
alias typeof(this) T;
alias ArrayList!T TList;
T[] pa;
//auto pl = new TList(pa); // NOW IT WORKS !
void opCatAssign(T v) {
pa ~= v;
}
Well I am a D noob. Have to investigate a bit more, and of course any
help is welcome :)
Bjoern
Re: dcollections ArrayList pb with mixin template
Steven Schveighoffer: I think a member initializer has to be a constant expression, like int i = 1. Anything else has to be done in the constructor. There are the static constructors too, for modules, structs, classes. Bye, bearophile
Re: dcollections ArrayList pb with mixin template
On 02/07/2010 00:26, bearophile wrote: Steven Schveighoffer: I think a member initializer has to be a constant expression, like int i = 1. Anything else has to be done in the constructor. There are the static constructors too, for modules, structs, classes. Bye, bearophile Hi bearophile, I don't understand (in this context) . Can you please elaborate a bit more ? thanks bjoern
Re: dcollections ArrayList pb with mixin template
BLS:
I don't understand (in this context) . Can you please elaborate a bit more ?
I have not shown you code because I don't understand your context. But you can
put inside static this() {...} code that can't be run statically, like the
initialization of a run-time thing.
Bye,
bearophile
