Re: Reference to D class instance with a C library
On 2013-07-13 20:53, Leandro Motta Barros wrote: Hey, thanks! This makes sense :-) Am I now wondering... how safe, portable and future proof would this be? If some future version of D implements a garbage collector capable of moving objects around the heap, I could get in trouble, right? Walter has always said that there's nothing in the language (D) that stops it from having moveable GC. In this case we would hope there would be way to pin objects. -- /Jacob Carlborg
Re: Conditional Inheritance
I assume that you template ends up creating a dummy interface though and this isn't really acceptable. Yes, it does. Once ':' is typed, some inheritance must occur. Why isn't a dummy interface acceptable?
Re: Conditional Inheritance
On 2013-07-14, 07:00, JS wrote:
I need to conditionally inherit:
interface A(T) : conditionallyInherit!(isBasicType!T, B);
A!(double) will inherit B but A!(mytype) won't.
template conditionallyInherit(bool choice, T...) {
static if (choice) {
alias conditionallyInherit = T;
} else {
import std.typetuple : TypeTuple;
alias conditionallyInherit = TypeTuple!();
}
}
Should work.
--
Simen
Re: Conditional Inheritance
On 2013-07-14, 07:40, JS wrote: On Sunday, 14 July 2013 at 05:30:57 UTC, lomereiter wrote: On Sunday, 14 July 2013 at 05:04:37 UTC, JS wrote: and while I'm at it I need to conditionally constrain types. interface A(T) where(!isBasicType!T, (T : B)); which is suppose to require T to inherit from B if T is not basic type. interface A(T) if (isBasicType!T || is(T : B)) Thanks, works. I remember seeing code like this somewhere but couldn't find any docs about it. Here. I admit there should probably be more examples, and perhaps also some info on the classes/interfaces/structs unions pages. http://dlang.org/template.html#Constraint -- Simen
UDA's for enum values?
I would like to do something like
enum e
{
@(string) p,
@(int) i
}
class a
{
mixin(generatePropertiesFromEnum!e);
}
which would produce the result
interface a
{
@property string p();
@property int i();
}
I can generate the properties without issue but I can't seem to
attach properties to elements in the enum. I guess this is a
inverse-feature feature of D?
Re: UDA's for enum values?
that should be interface a instead of class a.
Re: UDA's for enum values?
On Sunday, 14 July 2013 at 12:33:07 UTC, JS wrote: I would like to do something like ... Looks like a grammar issue. UDA's are supposed to be attached to any symbol declaration as far as I understand, which enum members definitely are. Probably worth bugzilla entry.
Re: Conditional Inheritance
On 07/14/2013 11:37 AM, lomereiter wrote:
I assume that you template ends up creating a dummy interface though
and this isn't really acceptable.
Yes, it does. Once ':' is typed, some inheritance must occur.
Nope.
template Seq(T...){ alias T Seq; }
class C : Seq!(){ }
Why isn't a dummy interface acceptable?
It creates unnecessary bloat.
template conditionallyInherit(bool inherit, T) {
static if(inherit) alias T conditionallyInherit;
else alias Seq!() conditionallyInherit;
}
Re: UDA's for enum values?
On Sunday, 14 July 2013 at 13:38:41 UTC, Dicebot wrote: On Sunday, 14 July 2013 at 12:33:07 UTC, JS wrote: I would like to do something like ... Looks like a grammar issue. UDA's are supposed to be attached to any symbol declaration as far as I understand, which enum members definitely are. Probably worth bugzilla entry. Looks like http://d.puremagic.com/issues/show_bug.cgi?id=9701
Re: DLLs: Cleaning up
On 07/11/2013 05:58 AM, Chris wrote: I have a DLL written in D I load into a Python application via ctypes like so: lib = CDLL(mydll) The DLL loads and can be used no problem. However, once the DLL is discarded of by the program, the program either doesn't react or crashes. I still haven't worked out how to clean up the DLL correctly before it is unloaded / detached (from Python). I guess it's the GC and/or some C stuff I've overlooked. I have tried both approaches described on this page: http://dlang.org/dll.html. Maybe someone of yous once had a similar problem and found a solution. Any hints or suggestions would be appreciated. Thanks. hmm. pyd uses the example under 'DLLs with a C Interface' for its windows dll code and it seems pretty stable, but then it doesn't use ctypes. It doesn't look like you need to be mucking with rt_init and rt_term, so maybe the garbage collector is trying to collect something that python still has a reference to? Also, if you can finagle a dll out of gdc I would love to hear about it. I have not used it on windows, though.
Re: Reference to D class instance with a C library
The documentation of GC.addRoot() (mentioned by Simen), contains this interesting piece of example code: // Also ensure that a moving collector does not relocate // the object. GC.setAttr(cast(void*)context, GC.BlkAttr.NO_MOVE); Looks like we *already* have the way to pin objects to their current memory location. (This compiles and is running without errors so far, though I didn't try to look if it is actually doing something under the hood -- which currently doesn't matter much, since the current GC doesn't move objects). (And yes, a GC.clrAttr() call does exist, too.) LMB On Sun, Jul 14, 2013 at 6:29 AM, Jacob Carlborg d...@me.com wrote: On 2013-07-13 20:53, Leandro Motta Barros wrote: Hey, thanks! This makes sense :-) Am I now wondering... how safe, portable and future proof would this be? If some future version of D implements a garbage collector capable of moving objects around the heap, I could get in trouble, right? Walter has always said that there's nothing in the language (D) that stops it from having moveable GC. In this case we would hope there would be way to pin objects. -- /Jacob Carlborg
interacting with a process with redirected stdin/stdout/stderr
I'm trying to interact with a process using std.process and
redirected stdin/stdout/stderr.
What would be the recommended way?
For example:
auto pipes=pipeShell(myprocess,Redirect.all);
while(true){
pipes.stdin.rawWrite(some_command);
foreach (line; pipes.stdout.byLine) {
//do something with line
}
}
This doesn't work because it might block inside pipes.stdout.byLine, as the
process is requesting more inputs to be written to its stdin before
outputting more bytes to its stdout.
What's the right approach?
* fcntl(fd, F_SETFL, O_NONBLOCK); didn't seem to work
* reading pipes.stdout inside a separate thread?
In that second case, how to cleanly dispose of a blocked thread when we no
longer need it?
Any detailed example would help.
Thanks!
enum inheritance
It would be nice to be able to use enums in a hierarchical way:
enum colors
{
enum Red { RedOrange, ... }
enum Green { GreenBlue, ...}
enum Blue { BlueYellow, ... }
...
}
which would be the same as the flattened version,
enum colors
{
Red, RedOrange, ..., Green, GreenBlue, ..., Blue, BlueYellow,
..., ...
}
but we could dereference such as
colors.Red.RedOrange,
colors.Blue,
colors.Green.GreenBlue,
(This isn't a great example but demonstrates what I would like to
be able to do)
Is anything like this possible?
Re: enum inheritance
BTW, the usefulness is to group sub-enums into the same range.
This would make it easy/efficient to branch over a range in the
enum:
if (v in colors.Red) { v is a color in red }
instead of
if (v is color.Red || v is color.RedOrange || ...)
Re: enum inheritance
On Monday, 15 July 2013 at 04:27:42 UTC, JS wrote:
BTW, the usefulness is to group sub-enums into the same range.
This would make it easy/efficient to branch over a range in the
enum:
if (v in colors.Red) { v is a color in red }
instead of
if (v is color.Red || v is color.RedOrange || ...)
I guess a more intelligent structure is needed so changes in the
enum do not break binaries. (although this is already somewhat of
an issue with enums as changes in order requires a re-compilation)
