Does D has built-in stack structure?
Does D has built-in stack structure (if so, which module?) or should I implement it myself?
type of a variable as a mixin-able string?
Suppose I have:
import std.range;
auto a=iota(complex_expr_returning_3());
I'd like to have a function/trait/template/compiler magic that takes
variable a and generates a string that can be mixed in to represent the
type of a. The difficulty is that typeid(a).to!string doesn't work for
Voldermort types:
typeid(a).to!string produces "std.range.iota!(int, int).iota.Result", which
is not very useful as it can't be mixed in a program, being a voldemort
type, eg:
mixin("std.range.iota!(int, int).iota.Result a;"); //compile error
However, the compiler could help reduce it to something as simple as
possible, eg:
"typeof(iota(int.init))"
here this would work:
mixin("typeof(iota(int.init)) a;"); //works
Is it possible to do that in a generic way, such that it hides as much as
possible the details of the expression (here, "complex_expr_returning_3()"
should be simplified to int.init)
Or is there another trick I could use to instantiate a variable with same
type as a?
NOTE:
typeof(a) a2;
works even though
http://www.drdobbs.com/cpp/voldemort-types-in-d/232901591?pgno=2 says it
won't work, "Sorry, that won't work, the compiler will not allow a
Voldemort Type to be instantiated outside of its scope "
(although that's doesn't help with my original problem)
Re: Exec function D from C++
On 21/06/15 16:09, Sean Campbell wrote:
extern(C++) void d_initialize() {
Runtime.initialize();
}
extern(C++) void d_terminate()
{
Runtime.terminate();
}
These two functions are not necessary. There are already functions in
druntime which are supposed to be called from C/C++:
extern (C) bool rt_init();
extern (C) bool rt_term();
--
/Jacob Carlborg
Re: Exec function D from C++
On Sunday, 21 June 2015 at 13:12:03 UTC, MGW wrote:
Linux 32, dmd 2.067.0
I want to connect and execute function D from main() C++.
d1.d
import core.stdc.stdio;
extern (C++) void d1() {
printf("printf - exec d1()");
}
main_c1.cpp
#include
void d1(void);
int main(void) {
d1();
return 0;
}
compile
dmd -c d1.d
gcc main_c1.cpp d1.o libphobos2.a -lpthread -o main_c1
./main_c1 ---> This option works correctly!
If I try to cause the functions connected to GC in the D
function, there is an error.
d1.d
import import std.stdio;
extern (C++) void d1() {
writeln("writeln - exec d1()");
}
compile
dmd -c d1.d
gcc main_c1.cpp d1.o libphobos2.a -lpthread -o main_c1
./main_c1 ---> Error:
'./main_c1' terminated by signal SIGSEGV (Address boundary
error)
Examples from dmd2/html/d/dll-linux.html don't work if instead
of printf()
to use writeln(). I think that a problem in initialization of
Phobos.
actually its that druntime hasn't been initialized just add:
import core.runtime;
import std.stdio;
extern(C++) void d1() {
writeln("writeln - exec d1()");
}
extern(C++) void d_initialize() {
Runtime.initialize();
}
extern(C++) void d_terminate()
{
Runtime.terminate();
}
and the C++
#include
void d1(void);
void d_initialize(void);
void d_terminate(void);
int main(void) {
d_initialize();
d1();
d_terminate();
return 0;
}
Exec function D from C++
Linux 32, dmd 2.067.0
I want to connect and execute function D from main() C++.
d1.d
import core.stdc.stdio;
extern (C++) void d1() {
printf("printf - exec d1()");
}
main_c1.cpp
#include
void d1(void);
int main(void) {
d1();
return 0;
}
compile
dmd -c d1.d
gcc main_c1.cpp d1.o libphobos2.a -lpthread -o main_c1
./main_c1 ---> This option works correctly!
If I try to cause the functions connected to GC in the D
function, there is an error.
d1.d
import import std.stdio;
extern (C++) void d1() {
writeln("writeln - exec d1()");
}
compile
dmd -c d1.d
gcc main_c1.cpp d1.o libphobos2.a -lpthread -o main_c1
./main_c1 ---> Error:
'./main_c1' terminated by signal SIGSEGV (Address boundary error)
Examples from dmd2/html/d/dll-linux.html don't work if instead of
printf()
to use writeln(). I think that a problem in initialization of
Phobos.
Re: Passing functions as template parameter and assigning default values to them
On Sunday, 21 June 2015 at 10:06:15 UTC, biozic wrote:
You can use a template alias parameter with a default value
that is your default lambda:
int indexOfMax(alias fun = a => a, R)(R range)
{
// Use `fun` here like a function.
}
-- Nico
Thanks a lot, it works !!
Re: Passing functions as template parameter and assigning default values to them
On Sunday, 21 June 2015 at 09:34:51 UTC, kerdemdemir wrote:
Hi,
I need to find the index of maximum element so my code:
int indexOfMax(R)(R range)
{
alias Type = typeof(range.front().re); > I don't like
.re here
Type max = 0;
size_t maxIndex = 0;
foreach ( index,elem; range )
{
if ( elem.re > max )-> And also here
{
max = elem.re;
maxIndex = index;
}
}
return maxIndex;
}
Since my range contains Complex!double types I have to add
".re" for current implementation. But I want to be more
generic. Like how std.algorithm.map is.
Like: range.map!(a => a.re).
So what I want to achive is :
indexOfMax!(a => a.re)(complexRange); > implement algorithm
on a.re
indexOfMax(intRange); -> if a function is not given act
like (a => a)
Any advice with template function parameters or mixins will
make me happy.
Regards
Erdem
You can use a template alias parameter with a default value that
is your default lambda:
int indexOfMax(alias fun = a => a, R)(R range)
{
// Use `fun` here like a function.
}
-- Nico
Passing functions as template parameter and assigning default values to them
Hi,
I need to find the index of maximum element so my code:
int indexOfMax(R)(R range)
{
alias Type = typeof(range.front().re); > I don't like
.re here
Type max = 0;
size_t maxIndex = 0;
foreach ( index,elem; range )
{
if ( elem.re > max )-> And also here
{
max = elem.re;
maxIndex = index;
}
}
return maxIndex;
}
Since my range contains Complex!double types I have to add ".re"
for current implementation. But I want to be more generic. Like
how std.algorithm.map is.
Like: range.map!(a => a.re).
So what I want to achive is :
indexOfMax!(a => a.re)(complexRange); > implement algorithm
on a.re
indexOfMax(intRange); -> if a function is not given act like
(a => a)
Any advice with template function parameters or mixins will make
me happy.
Regards
Erdem
Re: pass by value && elide dtor + post-blit
Dear Ali,
thank you for helping! Problem happens when passing by value as
in param.
Change 'foo' to this:
ref S foo(ref S s)
{
s.val+=1;
return s;
}
Re: pass by value && elide dtor + post-blit
On Saturday, 20 June 2015 at 22:44:17 UTC, Ali Çehreli wrote:
On 06/20/2015 02:09 PM, Xiaoxi wrote:
The output:
before
deneme.S.this
after
deneme.S.~this
Ali
Dear Ali,
thank you for helping! Problem happens when passing by value as
in param.
DMD32 D Compiler v2.067.0
deneme.S.this
before
deneme.S.__postblit
deneme.S.__postblit
deneme.S.~this
deneme.S.~this
after
deneme.S.~this
import std.stdio;
struct S
{
int val;
this(int par)
{
val = par;
writeln(__FUNCTION__);
}
this(this)
{
writeln(__FUNCTION__);
}
~this()
{
writeln(__FUNCTION__);
}
}
S foo(S s)
{
s.val+=1;
return s;
}
void main()
{
auto s = S(42);
writeln("before");
foo(s);
writeln("after");
}
