Re: Delegates: Print 0..9
On Thursday, 1 December 2016 at 20:12:15 UTC, Ali Çehreli wrote: First, the scary syntax that produces a lambda from an int: ... Better: ... All methods.. Thank you!
Re: Two part question. Making a dynamic array of delegates, and taking in a delegate with unknown parameters as an argument .
Thank you all for the replies. I'm extremely grateful. I'll look into each and every answer.
Re: Two part question. Making a dynamic array of delegates, and taking in a delegate with unknown parameters as an argument .
On Thursday, 1 December 2016 at 23:51:19 UTC, Payotz wrote:
The register method will take in delegates as an argument, but
those delegates have varied arguments themselves, so I can't
really put anything there. I know that it's got something to do
with templates so I tried my hand in it and came up with this:
void registerEvent(string event_name,T...)(T delegate() dg);
Off the top of my head, you should be able to do something like
this:
void registerEvent(string event_name, T, Args...)(T
delegate(Args) dg) {}
I know there's something missing in the way I did it, so I'll
be glad for you folks to tell me what I'm missing.
And for the second part of the question, I can't seem to make a
Dynamic Array where I could store the delegates taken in the
"registerEvent" method. Closest thing I have gotten to is this:
private void delegate(T)(T args)[string] event;
which resulted in the compiler screaming Error signs at me.
So how does one do it?
This isn't going to work because you can't have an array of mixed
types. Something like `KyeEvent delegate() dg` and `MouseEvent
delegate() dg` are distinct types, so they can't be stored in the
same array.
Since you say the delegates have different parameters, the only
option I'm aware of to store them is to use either the Variant or
Algebraic type in std.variant. If only the return type differed,
there would be other options. And I don't know what you're doing
with that event_name template parameter. But anyway, checkout
std.variant.
Re: Two part question. Making a dynamic array of delegates, and taking in a delegate with unknown parameters as an argument .
On Thursday, 1 December 2016 at 23:51:19 UTC, Payotz wrote: So, to give context, I am trying to make an event manager for a game I'm making. I was writing the "register()" method so I ran into a problem. The register method will take in delegates as an argument, but those delegates have varied arguments themselves, so I can't really put anything there. I know that it's got something to do with templates so I tried my hand in it and came up with this: void registerEvent(string event_name,T...)(T delegate() dg); You could do what pthread does in C to achieve similar goals. void delegate(void*); // or int delegate(void*) if you want to return an error code and then store the void pointer along with the delegate and then cast the void* to the correct type (a struct of arguments or similar) and call it later. not very safe but there are ways to make it nicer. However if the set of types of events is closed you can use ailas event = Algebraic!(ev1,ev2,ev3...); where ev1 and so on are structs that hold parameters of the event. and have void delegate(event); This is effectively how SDL does events. I know there's something missing in the way I did it, so I'll be glad for you folks to tell me what I'm missing. And for the second part of the question, I can't seem to make a Dynamic Array where I could store the delegates taken in the "registerEvent" method. Closest thing I have gotten to is this: private void delegate(T)(T args)[string] event; which resulted in the compiler screaming Error signs at me. So how does one do it? You get an error here because you are trying to have an associative array of templates. if they were all void delegate(int)'s that would work. You can't use an uninstantiated template as a type.
Re: Two part question. Making a dynamic array of delegates, and taking in a delegate with unknown parameters as an argument .
On Thursday, 1 December 2016 at 23:51:19 UTC, Payotz wrote: So, to give context, I am trying to make an event manager for a game I'm making. I was writing the "register()" method so I ran into a problem. The register method will take in delegates as an argument, but those delegates have varied arguments themselves, so I can't really put anything there. I know that it's got something to do with templates so I tried my hand in it and came up with this: void registerEvent(string event_name,T...)(T delegate() dg); May be std.variant will help you. https://dlang.org/phobos/std_variant.html You can bring the delegates to a common interface, hiding the differences in std.variant
Re: Two part question. Making a dynamic array of delegates, and taking in a delegate with unknown parameters as an argument .
On 12/01/2016 03:51 PM, Payotz wrote:
> So, to give context, I am trying to make an event manager for a game I'm
> making.
> I was writing the "register()" method so I ran into a problem.
>
> The register method will take in delegates as an argument, but those
> delegates have varied arguments themselves, so I can't really put
> anything there.
What you know is how you will call them. Let's assume just an int argument.
> I know that it's got something to do with templates so I
> tried my hand in it and came up with this:
>
> void registerEvent(string event_name,T...)(T delegate() dg);
Binding state to callables is pretty easy in D. You don't want to pass
the arguments to the registration because it wouldn't know what to do
with those: Store the state for the delegate? Maybe, maybe not.
> I know there's something missing in the way I did it, so I'll be glad
> for you folks to tell me what I'm missing.
All you need is your interface to these callbacks.
> And for the second part of the question, I can't seem to make a Dynamic
> Array where I could store the delegates taken in the "registerEvent"
> method. Closest thing I have gotten to is this:
>
> private void delegate(T)(T args)[string] event;
>
> which resulted in the compiler screaming Error signs at me.
> So how does one do it?
Here is a start:
import std.stdio;
alias Func = void delegate(int);
Func[string] registry;
void register(string event_name, Func func) {
registry[event_name] = func;
}
struct S {
double d;
string s;
void foo(int i) {
writefln("S.foo called with %s; my state: %s", i, this);
}
}
void bar(int i) {
writefln("bar called with %s", i);
}
void main() {
register("trivial", (int a) => writefln("called with %s", a));
auto s = S(2.5, "hello");
register("with_struct", );
int j;
register("using_local_state", (int a) {
++j;
writefln("Incremented local j: %s", j);
});
// This won't work as because is not a delegate, but a
function.
// Very simple with toDelegate.
// http://dlang.org/phobos/std_functional.html#toDelegate
import std.functional: toDelegate;
register("regular_function", toDelegate());
foreach (event_name, func; registry) {
writefln("--- Calling function registered for %s", event_name);
func(cast(int)event_name.length);
}
}
Ali
Re: Two part question. Making a dynamic array of delegates, and taking in a delegate with unknown parameters as an argument .
On Thu, Dec 01, 2016 at 11:51:19PM +, Payotz via Digitalmars-d-learn wrote: > So, to give context, I am trying to make an event manager for a game > I'm making. > I was writing the "register()" method so I ran into a problem. > > The register method will take in delegates as an argument, but those > delegates have varied arguments themselves, so I can't really put > anything there. I know that it's got something to do with templates so > I tried my hand in it and came up with this: > > void registerEvent(string event_name,T...)(T delegate() dg); > > I know there's something missing in the way I did it, so I'll be glad > for you folks to tell me what I'm missing. > > And for the second part of the question, I can't seem to make a > Dynamic Array where I could store the delegates taken in the > "registerEvent" method. Closest thing I have gotten to is this: > > private void delegate(T)(T args)[string] event; > > which resulted in the compiler screaming Error signs at me. > So how does one do it? This requires heavy trickery, because what you're essentially doing is taking a compile-time construct (type-safe variadic functions) and applying it at runtime (array elements don't know how many arguments they will have until actually initialized at runtime). The solution is non-obvious, but, thankfully, *possible*, 'cos D is just *that* awesome. ;-) An example of how to do this can be found in Adam Ruppe's eventloop.d module, available here: https://github.com/adamdruppe/arsd/blob/master/eventloop.d In particular, look at the `typehash` template, the addListener() and send() functions, and the WrappedListener interface (along with the wrap() function). That should give you the basic idea of what's involved. Past that, there are also some dirty implementation details you have to work with such as getPtrPair() that performs some compiler-dependent type-casting black magic just to tie things together. (Alternatively, you could just use eventloop.d in your game and save yourself the trouble of reinventing it yourself. ;-) It has a pretty nice API that I've used in my own projects quite successfuly.) T -- Shin: (n.) A device for finding furniture in the dark.
Two part question. Making a dynamic array of delegates, and taking in a delegate with unknown parameters as an argument .
So, to give context, I am trying to make an event manager for a game I'm making. I was writing the "register()" method so I ran into a problem. The register method will take in delegates as an argument, but those delegates have varied arguments themselves, so I can't really put anything there. I know that it's got something to do with templates so I tried my hand in it and came up with this: void registerEvent(string event_name,T...)(T delegate() dg); I know there's something missing in the way I did it, so I'll be glad for you folks to tell me what I'm missing. And for the second part of the question, I can't seem to make a Dynamic Array where I could store the delegates taken in the "registerEvent" method. Closest thing I have gotten to is this: private void delegate(T)(T args)[string] event; which resulted in the compiler screaming Error signs at me. So how does one do it?
Re: The module 'foo' is already defined in 'libmylib.so'
On Thursday, 1 December 2016 at 22:05:06 UTC, Timothee Cour wrote: I want to update a library with new symbols (ie partial recompilation): libmylib.so : compiled from bar.d and foo.d now update the file foo.d dmd -c -fPIC foo.d -offoo.o clang++ -o libmylib_update.so foo.o -shared -Wl,-lmylib When trying to dlopen libmylib_update.so from C++ it fails with: The module 'foo' is already defined in 'libmylib.so' (it somehow works when the dlopen is called from D) How would I achieve that? Have a look at what `trace -E d_executable args` and `trace -E c++_executable args` print on startup and grep for dlopen calls and the like.
The module 'foo' is already defined in 'libmylib.so'
I want to update a library with new symbols (ie partial recompilation): libmylib.so : compiled from bar.d and foo.d now update the file foo.d dmd -c -fPIC foo.d -offoo.o clang++ -o libmylib_update.so foo.o -shared -Wl,-lmylib When trying to dlopen libmylib_update.so from C++ it fails with: The module 'foo' is already defined in 'libmylib.so' (it somehow works when the dlopen is called from D) How would I achieve that?
Re: Delegates: Print 0..9
On 12/01/2016 11:28 AM, unDEFER wrote:
> Hello!
> Simple using of delegates:
>
> ===
> #!/usr/bin/rdmd
> import std.stdio;
>
> void main()
> {
> void delegate() functions[];
>
> foreach (i; 0..10)
> {
> void print()
> {
> writefln("%s", i);
> }
>
> functions ~=
> }
>
> foreach (i; 0..10)
> {
> functions[i]();
> }
> }
> =
>
> Prints
> $ ./delegates.d
> 9
> 9
> 9
> 9
> 9
> 9
> 9
> 9
> 9
> 9
>
> How to print 0..9?
This is a common issue with D and some other languages (as I had learned
during a Dart language presentation, of which Dart does not suffer
from). All those delegates do close on the same loop variable. You need
to produce copies of the variable.
First, the scary syntax that produces a lambda from an int:
import std.stdio;
void main()
{
// Note: dmd's -de command line switch warned me about the use of
// C-style syntax, so I moved the brackets after the type name:
void delegate()[] functions;
foreach (i; 0..10)
{
void print(int j)
{
writefln("%s", j);
}
functions ~= ((a) => (() => print(a)))(i); // <-- SCARY
}
foreach (i; 0..10)
{
functions[i]();
}
}
Better:
// Returns a lambda
auto makePrinter(int j) {
return { // <-- returns a lambda
writefln("%s", j);
};
}
functions ~= makePrinter(i);
But of course there are better ways of doing things e.g. producing
numbers. Here is one with D's ranges:
import std.stdio: writeln;
import std.range: iota;
import std.algorithm: each;
void main() {
10.iota.each!writeln;
}
Ali
Re: Delegates: Print 0..9
Yes, I have found:
=
#!/usr/bin/rdmd
import std.stdio;
void main()
{
void delegate() functions[];
foreach (i; 0..10)
{
auto get_print(int i)
{
void print()
{
writefln("%s", i);
}
return
}
functions ~= get_print(i);
}
foreach (i; 0..10)
{
functions[i]();
}
}
=
Thank you!
Re: how to catch D Throwables (or exceptions) from C++?
On Thursday, 1 December 2016 at 01:58:13 UTC, Timothee Cour wrote:
eg:
```
dlib.d:
extern(C) void dfun(){assert(0, "some_msg");}
clib.cpp:
extern "C" void dfun();
void fun(){
try{
dfun();
}
catch(...){
// works but how do i get "some_msg" thrown from D?
}
}
```
I had the a similar problem when writing bindings to the RtMidi
library back in 2013.
I opted for catching C++ exceptions in C++, wrap the functions in
a C API; the C API returns a special type that contains a status,
a result and an error message.
On the D side, when a status is false, a D exception is raised,
mirroring the one that was caught in C++.
This strategy is described in dconf 2014:
https://www.youtube.com/watch?v=1JZNvKhA3mA=20m45s
It should be working the other way arround: catch a D exception
in D, return a wrapped value: on the C++ side, if the wrapped
value status is false, throw an exception
Below is an sample of the code I wrote:
In C++:
```
* Special return type.
* - success is true when a call went right,
* is false when an exception occured.
* - errMsg can be used to throw a D exception.
* - value is the value to be returned from a call.
*/
template
struct answer {
int success;
T value;
const char * errMsg;
};
* Predefined types of return for RtMidi. */
typedef answer answerRtMidiIn_p;
typedef answer answerRtMidiOut_p;
typedef answer answerBool;
typedef answer answerConstChar_p;
typedef answer answerDouble;
answerRtMidiIn_p RtMidiIn_new (
int api,
char * clientName,
unsigned int queueSizeLimit)
{
RtMidiIn * ptr;
try {
const std::string name = std::string (clientName);
ptr = new RtMidiIn ((RtMidi::Api) api, name,
queueSizeLimit);
answerRtMidiIn_p ans = {true, ptr, ""};
return ans;
} catch (RtError & error) {
answerRtMidiIn_p ans = {false, 0, error.getMessage
().c_str ()};
return ans;
}
}
```
in D:
```
/* Special return type.
* - success is true when a call went right,
* is false when an exception occured.
* - errMsg can be used to throw a D exception.
* - value is the value to be returned from a call.
*/
struct answer (T) {
int success;
T value;
const (char) * errMsg;
}
extern (C) {
// ...
answer!(void *) RtMidiIn_new (
int api,
immutable(char) * clientName,
uint queueSizeLimit);
// ...
}
class RtMidiIn {
// Pointer to the C++ class, package visibility.
protected void * ptr;
public:
this (
int api = UNSPECIFIED,
string clientName = "RtMidi Input Client",
uint queueSizeLimit = 100)
{
answer!(void *) ans
= RtMidiIn_new (api,
clientName.toStringz,
queueSizeLimit);
if (! ans.success)
throw new RtError (ans.errMsg.to!string);
this.ptr = ans.value;
}
// ...
}
```
Delegates: Print 0..9
Hello!
Simple using of delegates:
===
#!/usr/bin/rdmd
import std.stdio;
void main()
{
void delegate() functions[];
foreach (i; 0..10)
{
void print()
{
writefln("%s", i);
}
functions ~=
}
foreach (i; 0..10)
{
functions[i]();
}
}
=
Prints
$ ./delegates.d
9
9
9
9
9
9
9
9
9
9
How to print 0..9?
Re: How to serialize a double.
On Thursday, 1 December 2016 at 07:13:45 UTC, Bauss wrote:
On Thursday, 1 December 2016 at 00:36:30 UTC, Jake Pittis wrote:
[...]
You could do something like below which will allow you to
serialize any number.
import std.stdio : writeln;
import std.traits : isNumeric;
ubyte[] bytes(T)(T num) if (isNumeric!T) {
auto buf = new ubyte[T.sizeof];
(*cast(T*)(buf.ptr)) = num;
return buf;
}
T value(T)(ubyte[] buf) if (isNumeric!T) {
return (*cast(T*)(buf.ptr));
}
And example usage:
double foo = 3.14;
writeln(foo); // Prints 3.14
ubyte[] bar = foo.bytes;
writeln(bar); // Prints the bytes equal to 3.14
foo = bar.value!double;
writeln(foo); // Prints 3.14
Regarding the test assertion that failed. Turns out I had a bug
in the test. (of course)
This last solution is very pretty. Thanks.
You folks are all so kind!
