Re: How to know if opSlice is defined for a type (including built-in types)?

[chardetm via Digitalmars-d-learn]

On Wednesday, 20 January 2016 at 15:25:10 UTC, Jonathan M Davis 
wrote:
On Wednesday, January 20, 2016 13:06:00 chardetm via 
Digitalmars-d-learn wrote:
Anyone who has the same problem: I found 
std.range.primitives.hasSlicing 
(https://dlang.org/phobos/std_range_primitives.html#hasSlicing) which does exactly what I want!


Note that because strings are treated as ranges of dchar 
regardless of what their actual character type is, arrays of 
char and wchar (so-called "narrow" strings) are not consider to 
have slicing or random access by the traits in std.range. So, 
hasSlicing!string is false, though for anything other than an 
array of char or wchar, it will do what you're looking for, 
whereas for arrays of char or wchar, you really shouldn't be 
using the slice operator on them without knowing that they're 
what you're operating on so that you take the Unicode issues 
into account correctly.


- Jonathan M Davis


Yes and that was the next step of my problem, it turned out that 
it was already taken into account by hasSlicing!


Thank you very much!

Re: How to know if opSlice is defined for a type (including built-in types)?

[chardetm via Digitalmars-d-learn]

On Wednesday, 20 January 2016 at 10:44:36 UTC, Rikki Cattermole 
wrote:


template CanSlice(T) {
	enum CanSlice = __traits(compiles, {T t; auto v = t[0 .. 1];}) 
|| __traits(compiles, {T t; auto v = t.opSlice();});

}

Should work.


Thanks it works just fine!

How to know if opSlice is defined for a type (including built-in types)?

[chardetm via Digitalmars-d-learn]

Hi everyone,

I was wondering if it was possible to know at compile time if 
opSlice is defined for a type, including built-in types like 
"string". Here is the code I have:



import std.stdio;

struct Test {
Test opSlice(size_t i, size_t j) {
return this; // We don't care what it returns
}
}

void main () {
string s = "Hello";
auto s2 = s[0..2];
static if (is(typeof())) writeln("Ok string");

Test t;
auto t2 = t[0..2];
static if (is(typeof())) writeln("Ok Test");
}

Output:
Ok Test


How to make it work for "string" too (if possible)? And is there 
a way to differentiate "opSlice()" from "opSlice(size_t, size_t)" 
(or "opSlice(T, T)" for any T)?


Thank you in advance!

Re: How to know if opSlice is defined for a type (including built-in types)?

[chardetm via Digitalmars-d-learn]

Anyone who has the same problem: I found 
std.range.primitives.hasSlicing 
(https://dlang.org/phobos/std_range_primitives.html#hasSlicing) 
which does exactly what I want!

Re: fromStringz problem with gdc

[chardetm via Digitalmars-d-learn]

On Monday, 6 April 2015 at 17:55:42 UTC, Iain Buclaw wrote:

On Monday, 6 April 2015 at 17:47:27 UTC, chardetm wrote:

Hello everyone,

I have a problem with the fromStringz function 
(std.string.fromStringz) when I try to compile with the GDC 
compiler (it works fine with DMD).


Here is a minimal code to see the error:


import std.stdio, std.string, std.c.stdlib;

int main () {
   char* s;
   s = cast(char*) malloc(2);
   s[0] = 'a';
   s[1] = '\0';
   writeln(fromStringz(s));
   return 0;
}


Compiling with DMD (works fine):
$ dmd testfsz.d

Compiling with GDC:
$ gdc testfsz.d -o testfsz
testfsz.d:8: error: undefined identifier fromStringz

It does the same thing on a friend's computer. I'm using GCC 
4.9.1 on Kubuntu 14.10.
Any idea where this comes from? Thanks in advance for your 
help!


fromStringz (in std.string) was introduced in D 2.066, gdc-4.9 
was shipped when 2.065 was released.


Iain.


Thanks! I will make my own version and use conditional 
compilation to import it or not in that case...

fromStringz problem with gdc

[chardetm via Digitalmars-d-learn]

Hello everyone,

I have a problem with the fromStringz function 
(std.string.fromStringz) when I try to compile with the GDC 
compiler (it works fine with DMD).


Here is a minimal code to see the error:


import std.stdio, std.string, std.c.stdlib;

int main () {
char* s;
s = cast(char*) malloc(2);
s[0] = 'a';
s[1] = '\0';
writeln(fromStringz(s));
return 0;
}


Compiling with DMD (works fine):
$ dmd testfsz.d

Compiling with GDC:
$ gdc testfsz.d -o testfsz
testfsz.d:8: error: undefined identifier fromStringz

It does the same thing on a friend's computer. I'm using GCC 
4.9.1 on Kubuntu 14.10.

Any idea where this comes from? Thanks in advance for your help!

Re: Class inside a Struct?

[chardetm via Digitalmars-d-learn]

Thanks a lot Ali, now it works perfectly!

It is quite hard to get used to D's logic, I have to stop 
thinking in terms of C++...


Anyway, thanks again!

Class inside a Struct?

[chardetm via Digitalmars-d-learn]

Hello everyone,

I am currently learning D by coding a project, but I encountered
a problem with one of my structures. I managed to reduce the code
to the minimum:




import std.stdio;
import std.container.rbtree;

struct Container {

private RedBlackTree!int _rbtree = new RedBlackTree!int;

void add (int elt) {
_rbtree.insert(elt);
}

void print () {
if (_rbtree.empty) {
writeln(empty);
} else {
foreach (l; _rbtree) {
write(l,  );
}
writeln();
}
}

}

int main () {
Container c1, c2;
c1.add(1);
c1.print();
c2.print();
return 0;
}




I don't understand why the output of this program is:

1
1


I expect it to be:

1
empty


I thank you in advance for your help!