Re: Partial ordering of constructors with type parameters
On Wednesday, 23 April 2014 at 22:07:32 UTC, John Colvin wrote:
On Wednesday, 23 April 2014 at 18:04:05 UTC, monarch_dodra
wrote:
If you can't update your compiler, an alternative is to make
your non-template version an actual template:
class Foo{
this(T : int)(T x){}
this(T)(T x) {}
}
I haven't tested, but wouldn't this be more precisely
equivalent?:
class Foo{
this()(int x){}
this(T)(T x) {}
}
*That* creates a conflict though :/
Re: On Concurrency
One key difference is that coroutines won't make your programs run faster. It is a modelling mechanism that can simplify your programs where you otherwise would have to implement a state machine. This is also my impression when I look at this code (see http://www.99-bottles-of-beer.net/language-d-2547.html) that implements 99 bottles of beer in D with fibers. What seems to be happening is some alternating handover of the CPU. But when I run the code all 4 cores of my machine are under load and it looks like the runtime were able to make things run in parallel somehow. Now I'm really confused ...
Re: Partial ordering of constructors with type parameters
On 4/24/14, monarch_dodra via Digitalmars-d-learn digitalmars-d-learn@puremagic.com wrote: *That* creates a conflict though :/ Are you sure? I can't reproduce.
Example of parse whole json answer.
I have a json string saved in a file ( example of json tweeter answer: https://dev.twitter.com/docs/api/1.1/get/statuses/user_timeline ). I am trying to read the whole json answer and print specific data (created_at, retweet_count, ..) . I am new at D Programming language and i was wondering if someone can help me or post some example that show how to parse json strings using std.json library. Thanks in advance.
Re: Example of parse whole json answer.
On Thursday, 24 April 2014 at 12:17:42 UTC, Nicolas wrote:
I have a json string saved in a file ( example of json tweeter
answer:
https://dev.twitter.com/docs/api/1.1/get/statuses/user_timeline
). I am trying to read the whole json answer and print specific
data (created_at, retweet_count, ..) . I am new at D
Programming language and i was wondering if someone can help me
or post some example that show how to parse json strings using
std.json library. Thanks in advance.
Here is something to get you started. The initial version of
this code was from Ali Cehreli, I can't remember what
modifications are mine, or if this is all straight form Ali.
If you intend to do any serious work with Json, I highly
recommend you check out Vibe.d (www.vibed.org) - more stuff to
learn but its JSON capabilities are awesome compared to what
std.json gives you.
import std.stdio;
import std.json;
import std.conv;
import std.file;
/**
Ali's example.
*/
struct Employee
{
string firstName;
string lastName;
}
void readEmployees( string employee_json_string )
{
JSONValue[string] document =
parseJSON(employee_json_string).object;
JSONValue[] employees = document[employees].array;
foreach (employeeJson; employees) {
JSONValue[string] employee = employeeJson.object;
string firstName = employee[firstName].str;
string lastName = employee[lastName].str;
auto e = Employee(firstName, lastName);
writeln(Constructed: , e);
}
}
void main()
{
// Assumes UTF-8 file
auto content =
`{
employees: [
{ firstName:Walter , lastName:Bright },
{ firstName:Andrei , lastName:Alexandrescu },
{ firstName:Celine , lastName:Dion }
]
}`;
readEmployees( content );
//Or to read the same thing from a file
readEmployees( readText( employees.json ) );
}
Re: Partial ordering of constructors with type parameters
On Thursday, 24 April 2014 at 10:12:15 UTC, Andrej Mitrovic via Digitalmars-d-learn wrote: On 4/24/14, monarch_dodra via Digitalmars-d-learn digitalmars-d-learn@puremagic.com wrote: *That* creates a conflict though :/ Are you sure? I can't reproduce. Weird. I can't either. I probably accidentally tested it on 2.063? Who cares; yes, it's more practical.
Temporarily protect array from garbage collection
Is it possible to temporarily prevent the garbage collector from
collecting a memory block even if there are no references to it?
The use case is as follows: I want to call a C library function
which expects to take ownership of a buffer. It looks something
like this:
alias FreeFunc = extern(C) void function(void*, void*)
nothrow;
extern(C) void foo(void* buf, size_t len,
FreeFunc free, void* ctx) nothrow;
Here, 'buf' is a pointer to the buffer, 'len' is the length of
the buffer, 'free' is a function to deallocate the buffer when
the library is done with it, and 'ctx' is a user-supplied context
pointer. Upon deallocation, 'free' receives two parameters; the
pointer to the buffer and the context pointer. The latter can be
anything, even null, as it is just passed to 'free' and not used
for anything else.
Here is the problem: I want to be able to use a
garbage-collected dynamic array with this function, but I don't
want to have to retain a reference to it in my program. (I don't
know when the C library will call the free function.) In other
words, I want something like this:
extern(C) void myFree(void* ptr, void* ctx)
{
enableGCFor(ptr);
}
auto arr = new int[123];
disableGCFor(arr);
foo(arr.ptr, arr.length, myFree, null);
arr = null;
Is this at all possible?
Thanks,
Lars
Re: Temporarily protect array from garbage collection
On Thu, 24 Apr 2014 19:55:37 +, Lars T. Kyllingstad wrote:
Is it possible to temporarily prevent the garbage collector from
collecting a memory block even if there are no references to it?
The use case is as follows: I want to call a C library function which
expects to take ownership of a buffer. It looks something like this:
alias FreeFunc = extern(C) void function(void*, void*)
nothrow;
extern(C) void foo(void* buf, size_t len,
FreeFunc free, void* ctx) nothrow;
Here, 'buf' is a pointer to the buffer, 'len' is the length of the
buffer, 'free' is a function to deallocate the buffer when the library
is done with it, and 'ctx' is a user-supplied context pointer. Upon
deallocation, 'free' receives two parameters; the pointer to the buffer
and the context pointer. The latter can be anything, even null, as it
is just passed to 'free' and not used for anything else.
Here is the problem: I want to be able to use a garbage-collected
dynamic array with this function, but I don't want to have to retain a
reference to it in my program. (I don't know when the C library will
call the free function.) In other words, I want something like this:
extern(C) void myFree(void* ptr, void* ctx)
{
enableGCFor(ptr);
}
auto arr = new int[123];
disableGCFor(arr);
foo(arr.ptr, arr.length, myFree, null);
arr = null;
Is this at all possible?
Thanks,
Lars
You can use GC.addRoot() from core.memory before passing the pointer to
the C function, then use GC.removeRoot in your myFree function.
Re: Temporarily protect array from garbage collection
On Thursday, 24 April 2014 at 20:09:38 UTC, Justin Whear wrote: You can use GC.addRoot() from core.memory before passing the pointer to the C function, then use GC.removeRoot in your myFree function. Perfect, thanks!
Problem with code coverage. No .lst files?
Hey all, I tried to use code coverage analysis for the first time tonight. I added the -cov switch to my unit test build, but no matter what I do, I can't seem to locate the produced .lst files. Is there something I should know that isn't in the docs that I might be doing wrong? I'm not sure what's going on here. Thanks, Jeremy
Re: Problem with code coverage. No .lst files?
On 04/24/2014 08:32 PM, Jeremy DeHaan wrote: added the -cov switch to my unit test build Then you must execute the program. :) Ali
