Difference between is and ==
What difference between if ((x = stdin.readln().chomp) is q) and if ((x = stdin.readln().chomp) == q) ?
Re: Difference between is and ==
On Tuesday, 4 February 2014 at 08:08:30 UTC, Suliman wrote: What difference between if ((x = stdin.readln().chomp) is q) and if ((x = stdin.readln().chomp) == q) ? My interpretation of tdpl p57: 'is' compares for alias equality for arrays and classes. Otherwise they are the same.
Re: Difference between is and ==
My interpretation of tdpl p57:
'is' compares for alias equality for arrays and classes.
Otherwise they are the same.
So should next code have same behavior if I will use is instead
of ==
import std.stdio;
import std.string;
void main()
{
getchar();
}
void getchar()
{
string x;
if ((x = stdin.readln().chomp) == q)
writeln(it's is q);
else
writeln(Not q);
}
In case I am using is, I have never get first if expression is
true.
Re: Difference between is and ==
On Tuesday, 4 February 2014 at 08:25:18 UTC, Suliman wrote:
My interpretation of tdpl p57:
'is' compares for alias equality for arrays and classes.
Otherwise they are the same.
So should next code have same behavior if I will use is instead
of ==
import std.stdio;
import std.string;
void main()
{
getchar();
}
void getchar()
{
string x;
if ((x = stdin.readln().chomp) == q)
writeln(it's is q);
else
writeln(Not q);
}
In case I am using is, I have never get first if expression is
true.
My guess is the following:
string is an immutable(char)[]. As string is an array, 'is'
checks for alias equality. x is not an alias for the (unnamed?)
string literal q.
Re: Difference between is and ==
Suliman: What difference between if ((x = stdin.readln().chomp) is q) and if ((x = stdin.readln().chomp) == q) ? is performs a raw comparison of just the values, and the value of a string is its ptr and length field. While == compares their contents. So you want to use == here because you are interested to see if x contains the char 'q', because while their lengths could be equal, their ptr is surely different. Bye, bearophile
Get struct template types
Hi,
given a struct like so:
struct S(alias N, T) {...}
is there a way to get the template parameters of S? Something
like:
S.typetuple[0] == N,
S.typetuple[1] == T
I've had a look at std.typecons and std.typetuple but I don't see
what I'm missing something and cannot see a way to do the above.
Thanks,
ed
Re: Get struct template types
On Tuesday, 4 February 2014 at 09:30:22 UTC, ed wrote:
Hi,
given a struct like so:
struct S(alias N, T) {...}
is there a way to get the template parameters of S? Something
like:
S.typetuple[0] == N,
S.typetuple[1] == T
I've had a look at std.typecons and std.typetuple but I don't
see what I'm missing something and cannot see a way to do the
above.
Thanks,
ed
typeof(N).stringof will return type of N as string
for details read http://dlang.org/expression.html
Re: 3d vector struct
On Monday, 3 February 2014 at 20:10:59 UTC, Brenton wrote: 6) Any other comments or suggestions? I know that the I'm learning the language factor plays a huge role, but after you are done studying your vector implementation, I think you could forget about it and use the ones provided by other libraries :P If you didn't knew about it, DUB is a marvelous software that gives you quick access to lots of nice libraries. EG: one you might be interested in is http://code.dlang.org/packages/gl3n Another one *might* be gfm: http://code.dlang.org/packages/gfm I'm also wondering where the hell did I put my raytracer code I did ages ago...
Re: Get struct template types
On Tuesday, 4 February 2014 at 09:39:48 UTC, evilrat wrote:
On Tuesday, 4 February 2014 at 09:30:22 UTC, ed wrote:
Hi,
given a struct like so:
struct S(alias N, T) {...}
is there a way to get the template parameters of S? Something
like:
S.typetuple[0] == N,
S.typetuple[1] == T
I've had a look at std.typecons and std.typetuple but I don't
see what I'm missing something and cannot see a way to do the
above.
Thanks,
ed
typeof(N).stringof will return type of N as string
for details read http://dlang.org/expression.html
oops sorry, it's for another people.
what are you trying to achieve? when passing types as template
args it is still types, so again typeof should give you type for
variables(in such cases there is typeof), otherwise type is type.
also, afaik it is not possible to store types in tuple, but i
think you can store variables in tuple and retrieve their types
at runtime
Decorators, Annotations, Macros, AST transforms…
…choose you favourite term.
Following on from trying to use D to write CPython extensions without
using PyD: entry points will be functions:
extern(C) type name() {
initializeIfNoAlreadyDone();
…
}
This immediately looks like a job for a Python decorator.
@pythonentry type name() {
…
}
From searching the Web there is DIP6 and DIP50, but what is the current
official way of doing this source to source transform in D just now.
Thanks.
--
Russel.
=
Dr Russel Winder t: +44 20 7585 2200 voip: sip:russel.win...@ekiga.net
41 Buckmaster Roadm: +44 7770 465 077 xmpp: rus...@winder.org.uk
London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder
Re: Python calling D
On Tue, 2014-02-04 at 07:13 +, Artem Tarasov wrote:
On Sunday, 2 February 2014 at 15:31:30 UTC, Russel Winder wrote:
result is:
| LD_LIBRARY_PATH=. python execute.py
Segmentation fault
You should call Runtime.initialize() prior to calling any other D
functions.
Hummm… obvious once pointed out :-) Thanks for doing exactly that.
The question is how to get this run. I tried a module initializer:
static this() {
Runtime.initialize();
}
but this module never actually gets loaded per se, so that is never
going to work. So this means calling a C linkage function to do the
initialization in every entry point:
import core.runtime: Runtime;
import std.stdio: writeln;
auto initialized = false;
extern (C) void initializeIfNotAlreadyDone() {
if (!initialized) {
Runtime.initialize();
initialized = true;
}
}
extern(C) {
void sayHello() {
initializeIfNotAlreadyDone();
writeln(Hello World.);
}
}
works a treat:
scons: Building targets ...
dmd -I. -fPIC -c -fPIC -ofhelloWorld.o helloWorld.d
dmd -shared -defaultlib=libphobos2.so -oflib_helloWorld.so helloWorld.o
-fPIC -L-L.
LD_LIBRARY_PATH=. python execute.py
Hello World.
scons: done building targets.
So D extensions to CPython are possible without PyD!
Now to continue with PyD anyway so as to compare and contrast.
--
Russel.
=
Dr Russel Winder t: +44 20 7585 2200 voip: sip:russel.win...@ekiga.net
41 Buckmaster Roadm: +44 7770 465 077 xmpp: rus...@winder.org.uk
London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder
Re: Get struct template types
On Tuesday, 4 February 2014 at 09:58:53 UTC, ed wrote:
On Tuesday, 4 February 2014 at 09:46:01 UTC, evilrat wrote:
On Tuesday, 4 February 2014 at 09:39:48 UTC, evilrat wrote:
On Tuesday, 4 February 2014 at 09:30:22 UTC, ed wrote:
Hi,
given a struct like so:
struct S(alias N, T) {...}
is there a way to get the template parameters of S?
Something like:
S.typetuple[0] == N,
S.typetuple[1] == T
I've had a look at std.typecons and std.typetuple but I
don't see what I'm missing something and cannot see a way to
do the above.
Thanks,
ed
typeof(N).stringof will return type of N as string
for details read http://dlang.org/expression.html
oops sorry, it's for another people.
what are you trying to achieve? when passing types as template
args it is still types, so again typeof should give you type
for variables(in such cases there is typeof), otherwise type
is type. also, afaik it is not possible to store types in
tuple, but i think you can store variables in tuple and
retrieve their types at runtime
I am trying to set up an isS, isSOfN or isSOfT so I can create
functions that allow restricted types of S based on all, or
only one of the template parameters.
Like so (pseudo-D code)
---
struct S(alias N, T) {}
//
// Hopefully it is clear what I am trying to do here
enum isSOfN = template(alias N,STYPE) {
static assert(N == STYPET.typetuple[0]);
}
enum isSOfT = template(T,STYPE) {
static assert(T == STYPET.typetuple[1]);
}
//
void f(T)(T t) if(isSOfN!(3, T)) { // allow S with N=3 and any
T (see below)
}
...
...
auto s3i = S!(3,int);
auto s3f = S!(3,float);
s3i.f(); // Succeeds
s3f.f(); // Succeeds
auto S4i = S!(4,int);
s4i.f(); // compile time error
--
I'm looking into T.stringof now, I might be able to get it
working with some compile-time string magic of D :)
If this is a bad way to go about it please let me know. I'm
trying to learn idiomatic D as I go.
Thanks,
ed
for this simple case static if is pretty straightforward, but
then if only purpose is to construct type it is better use
regular generic function and typecons i think.
--
import std.stdio;
struct S(alias N, T)
{
T x;
void f()
{
static if(N==3)
{
writeln(n = 3, type = , T.stringof);
}
else static if (N == 2)
{
writeln(n = 2, type = , T.stringof);
}
else
static assert(0, NO!);
}
}
void main()
{
S!(3, int) a; // ok
S!(2, float) b; // ok
S!(4, double) c; // oops
a.f();
b.f();
}
--
Re: Get struct template types
On Tuesday, 4 February 2014 at 09:30:22 UTC, ed wrote:
Hi,
given a struct like so:
struct S(alias N, T) {...}
is there a way to get the template parameters of S? Something
like:
S.typetuple[0] == N,
S.typetuple[1] == T
I've had a look at std.typecons and std.typetuple but I don't
see what I'm missing something and cannot see a way to do the
above.
Thanks,
ed
Use type deduction:
---
struct S(size_t n, T) {}
enum isS(T) = is(T == S!(n, U), size_t n, U);
template isS(T, size_t n)
{
static if(is(T == S!(n2, U), size_t n2, U))
enum isS = n == n2;
else
enum isS = false;
}
alias MyS = S!(3, float);
static assert(isS!MyS);
static assert(isS!(MyS, 3));
static assert(is(MyS == S!(3, float)));
---
Re: Templates: generic return null;
On Tuesday, 4 February 2014 at 00:43:54 UTC, TheFlyingFiddle
wrote:
On Monday, 3 February 2014 at 10:25:19 UTC, Chris wrote:
Is there a way I can make the return type in getAttribute
generic? null does not work with numbers.
MyStruct(T) {
T[T] attributes;
//
public auto getAttribute(T attr) {
if (!(attr in attributes)) {
return null; // Doesn't work for numbers!
}
return attributes[attr];
}
}
void main() {
auto myStr = MyStruct!int(0); // Error
}
Whenever i am faced with this situation i do one (or more then
one) of the following things.
struct MyStruct(T)
{
T[T] attributes;
//(1) Forward the underlying access method Eg:
auto opBinaryRight(string s : in)(T attrib)
{
return attrib in attributes;
}
//(2) make a try method.
bool tryAttrib(T attrib, out T outAttrib)
{
auto p = attrib in attributes;
if(p) outAttrib = *p;
return p !is null;
}
//(3) Give user option to set default value.
T attribOrDefault(T attrib, T default)
{
auto p = attrib im attributes;
return p is null ? default : attrib;
}
//(4) Use Nullable!T (I prefer #5 over this one)
Nullable!T attribOrNull(T attrib)
{
Nullable!T result;
auto p = attrib ib attributes;
if(p) result = *p;
return result;
}
//(5) Use a pointer but not forward in operator.
T* attribPtr(T attrib)
{
return attrib in attributes;
}
//(6) Throw exception (I only do this in combination with
one of the above)
T attribEx(T attrib)
{
return *enforce!AttribNotFoundEx(attrib in attributes);
}
}
Thanks for this brief outline.
My personal preference using #2 and #3 in combination. #2
covers the basic case Is this thing avalible? and #3 covers
the case Give it to me if it is avalible or use this default
value I think it gives a clear image of what your code is
doing at the callsite. Only using #2 or #3 limits you in this
sence.
Personally I don't like the idea of passing a default value on
the user side in this particular case. If the attribute has not
been set, there is a reason, and I don't want to operate with a
return value of something that has not been set at all.
I introduced a check similar to #2:
bool hasAttribute(T attr) { ... }
Of course, the user has to use if. Experimentally, I introduced
auto getAttribute(T attr) {
if (!(attr in attributes)) {
return T.init;
}
return attributes[attr];
}
to avoid the if statement and just gently move along, if the
attribute has not been set, which again leads to the problem of
#3, i.e. potentially operating with a value of something that
does not exist in the first place.
For #1, #4 and #5 i personally stay away from them. They force
the caller to either use an if or potentially trigger a null
pointer derecerence. (Btw what is the benefit of #4? I have
never used it since it seems pointless)
#4 is weird, but that's because I don't fully understand the
concept behind it.
I very rarly use attribEx. I don't think code shuld just spew
exceptions all over the place. They should be reserved for
really bad stuff, like bounds checks. One exception i make to
this rule is if i'm dealing with ranges. Since the other
methods don't lend themselfs for UFCS-chaing.
I agree. Exceptions should be reserved for serious cases or cases
where you simply cannot predict all cases (reading random input
from the internet, for example).
Re: Decorators, Annotations, Macros, AST transforms…
P.P.S. proof-of-concept implemenation of function attributes a bit more similar t python decorators : https://github.com/rejectedsoftware/vibe.d/blob/master/source/vibe/internal/meta/funcattr.d
Re: Python calling D
On Tuesday, 4 February 2014 at 11:33:40 UTC, Russel Winder wrote:
The question is how to get this run.
Pointing out obvious things, part 2: wrap it into a C function
and call that function when loading the Python module.
library.d:
...
extern (C) export void attach() { Runtime.initialize(); }
library/__init__.py:
...
lib = ctypes.CDLL(myawesomelib.so)
lib.attach()
def foo():
lib.foo()
...
How can i find my LAN IP Address using std.socket?
I'm trying to find my own ip address using std.socket with little success. How would i go about doing this? (It should be a AddressFamily.INET socket)
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 13:02:26 UTC, TheFlyingFiddle wrote: I'm trying to find my own ip address using std.socket with little success. How would i go about doing this? (It should be a AddressFamily.INET socket) You can have lot of different local IP addresses on a single machine so question can't be answered properly. However you may use in `Socket.hostName` and resolve it via DNS to find IP machine itself currently consuders as its main pulbic IP.
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 13:02:26 UTC, TheFlyingFiddle wrote: I'm trying to find my own ip address using std.socket with little success. How would i go about doing this? (It should be a AddressFamily.INET socket) Create a connection to another LAN machine with a known address (e.g. gateway or router), then use Socket's localAddress property to get your IP. You cannot really do that before establishing a connection, as Dicebot already mentioned.
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 13:21:54 UTC, Stanislav Blinov wrote: Create a connection to another LAN machine with a known address (e.g. gateway or router), then use Socket's localAddress property to get your IP. Worth noting that this solution is not reliable in general either because your server can possibly have complicated routing configurations that will make, for example, LAN destination packets go via different network interface than WAN destination ones. It is probably better to tell what high-level problem you are trying to solve to find most useful compromise.
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 13:13:07 UTC, Dicebot wrote: On Tuesday, 4 February 2014 at 13:02:26 UTC, TheFlyingFiddle wrote: I'm trying to find my own ip address using std.socket with little success. How would i go about doing this? (It should be a AddressFamily.INET socket) You can have lot of different local IP addresses on a single machine so question can't be answered properly. However you may use in `Socket.hostName` and resolve it via DNS to find IP machine itself currently consuders as its main pulbic IP. This works great thanks. I just need any (working) local IP address so getting more then one is not an issue for me.
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 13:21:54 UTC, Stanislav Blinov wrote: On Tuesday, 4 February 2014 at 13:02:26 UTC, TheFlyingFiddle wrote: I'm trying to find my own ip address using std.socket with little success. How would i go about doing this? (It should be a AddressFamily.INET socket) Create a connection to another LAN machine with a known address (e.g. gateway or router), then use Socket's localAddress property to get your IP. You cannot really do that before establishing a connection, as Dicebot already mentioned. Problem is that i don't know in what local network the server will be running, so this is unfortunatly not an option for me.
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 13:31:27 UTC, TheFlyingFiddle wrote: Problem is that i don't know in what local network the server will be running, so this is unfortunatly not an option for me. But if that's the case, the hostname solution may as well just give you your loopback address. :)
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 15:48:50 UTC, Vladimir Panteleev
wrote:
On Tuesday, 4 February 2014 at 13:02:26 UTC, TheFlyingFiddle
wrote:
I'm trying to find my own ip address using std.socket with
little success. How would i go about doing this? (It should be
a AddressFamily.INET socket)
This program will print all of your computer's IP addresses:
import std.socket;
import std.stdio;
void main()
{
foreach (addr; getAddress(Socket.hostName))
writeln(addr.toAddrString());
}
This includes IPv6 addresses. You can filter the address family
by checking addr's addressFamily property.
I am a bit lost in anything networking related, so I ran this on
my machine just for fun and it printed:
127.0.0.1
127.0.0.1
127.0.0.1
which based on my understanding is the local loopback address (I
am not completely, 100% ignorant).
However if I run /sbin/ifconfig I get:
enp7s0Link encap:Ethernet HWaddr 50:E5:49:9B:29:49
inet addr:10.1.101.52 Bcast:10.1.101.255
Mask:255.255.255.0
inet6 addr: fe80::52e5:49ff:fe9b:2949/64 Scope:Link
loLink encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
This computer is on a network with dynamically assigned IP
address (DHCP).
So shouldn't the 10.1.101.52 address have been reported?
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 16:02:33 UTC, Craig Dillabaugh wrote: However if I run /sbin/ifconfig I get: enp7s0Link encap:Ethernet HWaddr 50:E5:49:9B:29:49 inet addr:10.1.101.52 Bcast:10.1.101.255 Mask:255.255.255.0 inet6 addr: fe80::52e5:49ff:fe9b:2949/64 Scope:Link loLink encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host This computer is on a network with dynamically assigned IP address (DHCP). So shouldn't the 10.1.101.52 address have been reported? It results in all addresses you hostname resolvs to. On all desktop linux machines /etc/hosts is configured to resolve hostname to localhost by default. On servers it usually resolves to externally accessible one.
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 13:02:26 UTC, TheFlyingFiddle
wrote:
I'm trying to find my own ip address using std.socket with
little success. How would i go about doing this? (It should be
a AddressFamily.INET socket)
This program will print all of your computer's IP addresses:
import std.socket;
import std.stdio;
void main()
{
foreach (addr; getAddress(Socket.hostName))
writeln(addr.toAddrString());
}
This includes IPv6 addresses. You can filter the address family
by checking addr's addressFamily property.
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 16:13:33 UTC, Dicebot wrote: It results in all addresses you hostname resolvs to. On all desktop linux machines /etc/hosts is configured to resolve hostname to localhost by default. On servers it usually resolves to externally accessible one. Update: I have just checked and this is actually distro-specific right now. My Arch box does not have that /etc/hosts entry and resolves host name to whatever first configured network interface has. Ubuntu does have explicit host name entry in /etc/hosts which resolves to localhost.
Re: Python calling D
On Tue, 2014-02-04 at 12:45 +, Artem Tarasov wrote:
On Tuesday, 4 February 2014 at 11:33:40 UTC, Russel Winder wrote:
The question is how to get this run.
Pointing out obvious things, part 2: wrap it into a C function
and call that function when loading the Python module.
I had thought of this and rejected it as an API fail. (Possibly wrongly,
but…)
library.d:
...
extern (C) export void attach() { Runtime.initialize(); }
library/__init__.py:
...
lib = ctypes.CDLL(myawesomelib.so)
lib.attach()
This violates the principle of least surprise: you don't have to do this
with C or C++ extensions so it is an API fail for D to have to do this.
def foo():
lib.foo()
...
But it does lead to a working system :-)
--
Russel.
=
Dr Russel Winder t: +44 20 7585 2200 voip: sip:russel.win...@ekiga.net
41 Buckmaster Roadm: +44 7770 465 077 xmpp: rus...@winder.org.uk
London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 16:02:33 UTC, Craig Dillabaugh wrote: This computer is on a network with dynamically assigned IP address (DHCP). So shouldn't the 10.1.101.52 address have been reported? Nope. In out-of-the-box simple network setups (i.e. home network in the form PC/laptop - router - internet) the address resolution won't go further than your hosts file, which in turn will always give you back the loopback address (more specifically, the address that is specified for the hostname in aforementioned file). That's why both I and Dicebot mentioned there isn't any real way to query your local addresses without any live connection: only when a socket has a connection within a particular network can you tell your own IP address in that network. The address itself would depend on the network setup, your local routing configuration, etc. Your machine can have several network adaptors (ethernet boards, Wi-Fi, etc.), each configured with (numerous) routing setups, plus the routers they're connected to have their own routing setups... This can go on and on.
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 16:13:33 UTC, Dicebot wrote: On Tuesday, 4 February 2014 at 16:02:33 UTC, Craig Dillabaugh wrote: However if I run /sbin/ifconfig I get: enp7s0Link encap:Ethernet HWaddr 50:E5:49:9B:29:49 inet addr:10.1.101.52 Bcast:10.1.101.255 Mask:255.255.255.0 inet6 addr: fe80::52e5:49ff:fe9b:2949/64 Scope:Link loLink encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host This computer is on a network with dynamically assigned IP address (DHCP). So shouldn't the 10.1.101.52 address have been reported? It results in all addresses you hostname resolvs to. On all desktop linux machines /etc/hosts is configured to resolve hostname to localhost by default. On servers it usually resolves to externally accessible one. Thanks.
What does the alias attribute do here
What does the alias attribute do here:
void foo(alias bar)
{
...
}
What is the idea behind this attribute when used here?
Re: What does the alias attribute do here
On Tuesday, 4 February 2014 at 17:09:02 UTC, Gary Willoughby
wrote:
What does the alias attribute do here:
void foo(alias bar)
This specifically won't compile, alias params are only allowed in
a compile-time list. So
void foo(alias bar)() { ... }
would work.
Anyway, what it does is you pass another symbol to the
function/template and the alias parameter works as the same
thing. So let's play with:
void foo(alias bar)() {
import std.stdio;
writeln(bar);
}
void main() {
int a = 20;
foo!a(); // will print 20
}
What happened is foo!a passed the /symbol/, not just the variable
contents, the variable itself, as the alias parameter. An
important difference between this and a regular int parameter is
you can assign to it too:
void foo(alias a)() {
import std.stdio;
writeln(a);
a = 50; // this is as if we literally wrote cool = 50; in
main()
}
void main() {
int cool = 20;
foo!cool();
assert(cool == 50); // passes
}
alias parameters differ from regular parameters because a regular
parameter can only be a type name. An alias parameter can be
another variable.
You can also pass it functions and call them as if the user wrote
the call themselves - no pointers/delegates involved.
Help with array maniipulation
I have a C Struct:
typedef struct
{
enum LibRaw_image_formats type;
ushort height,
width,
colors,
bits;
unsigned int data_size;
unsigned char data[1];
}libraw_processed_image_t;
with a D version:
struct libraw_processed_image_t
{
LibRaw_image_formatstype;
ushort height,
width,
colors,
bits;
uintdata_size;
ubyte[1]data;
}
libraw_dcraw_make_mem_thumb() returns a pointer to this struct.
I need to create a char[] from the data and data_size members,
ideally without copying, to send to GdkPixbufLoader.write(char[]).
If I do this:
libraw_processed_image_t *img;
img = libraw_dcraw_make_mem_thumb();
char[] buf = cast(char[]) img.data[];
GdkPixbufLoader.write(buf); // Runtime error
buf.ptr == img.data.ptr and length of both arrays is 1.
If I try:
buf.length = img.data_size;
buf is reallocated.
Any suggestions to make buf.ptr == img.data.ptr and
buf.length = img.data_size?
Thanks
ollie
Re: Help with array maniipulation
On 02/04/2014 10:58 AM, ollie wrote: I have a C Struct: [...] uintdata_size; ubyte[1]data; Is that the C extension where the last array in a struct can have more elements than its size? That will be a problem in D. } libraw_dcraw_make_mem_thumb() returns a pointer to this struct. I need to create a char[] from the data and data_size members, ideally without copying, to send to GdkPixbufLoader.write(char[]). If I do this: libraw_processed_image_t *img; img = libraw_dcraw_make_mem_thumb(); char[] buf = cast(char[]) img.data[]; This: char[] buf = (cast(char*)img.data.ptr)[0 .. img.data_size]; However, as I said above, data won't have room for more than 1 element. In any case, treating a C array as a D slice is achieved by the following syntax: int[] D_slice = C_array[0 .. C_array_number_of_elements]; Ali
Re: Difference between is and ==
On Tue, 04 Feb 2014 03:08:28 -0500, Suliman everm...@live.ru wrote: What difference between if ((x = stdin.readln().chomp) is q) and if ((x = stdin.readln().chomp) == q) ? The first compares the pointer of the arrays. The second compares the contents of the array. Both check length as well for equality. In other words, the first will always be false (the ROM literal q will never have the same address as some heap block), the second will be true if the input was the string q. More generally, 'is' should be a bitwise comparison of the variables. '==' should check for logical equality, whatever that means for the variable types. -Steve
Re: What does the alias attribute do here
On Tuesday, 4 February 2014 at 17:17:13 UTC, Adam D. Ruppe wrote:
On Tuesday, 4 February 2014 at 17:09:02 UTC, Gary Willoughby
wrote:
What does the alias attribute do here:
void foo(alias bar)
This specifically won't compile, alias params are only allowed
in a compile-time list. So
void foo(alias bar)() { ... }
would work.
Anyway, what it does is you pass another symbol to the
function/template and the alias parameter works as the same
thing. So let's play with:
void foo(alias bar)() {
import std.stdio;
writeln(bar);
}
void main() {
int a = 20;
foo!a(); // will print 20
}
What happened is foo!a passed the /symbol/, not just the
variable contents, the variable itself, as the alias parameter.
An important difference between this and a regular int
parameter is you can assign to it too:
void foo(alias a)() {
import std.stdio;
writeln(a);
a = 50; // this is as if we literally wrote cool = 50;
in main()
}
void main() {
int cool = 20;
foo!cool();
assert(cool == 50); // passes
}
alias parameters differ from regular parameters because a
regular parameter can only be a type name. An alias parameter
can be another variable.
You can also pass it functions and call them as if the user
wrote the call themselves - no pointers/delegates involved.
Ah great, thanks that makes perfect sense.
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 13:24:59 UTC, Dicebot wrote: On Tuesday, 4 February 2014 at 13:21:54 UTC, Stanislav Blinov wrote: Worth noting that this solution is not reliable in general either because your server can possibly have complicated routing configurations that will make, for example, LAN destination packets go via different network interface than WAN destination ones. It is probably better to tell what high-level problem you are trying to solve to find most useful compromise. I'm setting up a simple local network enabling me to connect phones to the computer through the local wi-fi. The simplest way i could think of to make this work without relying on an external server was to simply broadcast the ip and port to all machines in the network.(Btw by server i mean my / my project groups windows boxes). So well the problem is that i need a way for the phones to find running servers on the LAN.
Re: Help with array maniipulation
On Tue, 04 Feb 2014 11:16:00 -0800, Ali Çehreli wrote: Is that the C extension where the last array in a struct can have more elements than its size? That will be a problem in D. yes it is. int[] D_slice = C_array[0 .. C_array_number_of_elements]; Thank you, that gives me what I was looking for. I thought I had tried something like that. Too many moving parts with threads and context changes to call GDK/GTK functions make things very precarious. I am still getting an access violation, but your help has moved me a step nearer a solution. Thanks, ollie
Re: How can i find my LAN IP Address using std.socket?
Am Tue, 04 Feb 2014 16:19:08 + schrieb Stanislav Blinov stanislav.bli...@gmail.com: On Tuesday, 4 February 2014 at 16:02:33 UTC, Craig Dillabaugh wrote: This computer is on a network with dynamically assigned IP address (DHCP). So shouldn't the 10.1.101.52 address have been reported? Nope. In out-of-the-box simple network setups (i.e. home network in the form PC/laptop - router - internet) the address resolution won't go further than your hosts file, which in turn will always give you back the loopback address (more specifically, the address that is specified for the hostname in aforementioned file). That's why both I and Dicebot mentioned there isn't any real way to query your local addresses without any live connection: only when a socket has a connection within a particular network can you tell your own IP address in that network. The address itself would depend on the network setup, your local routing configuration, etc. Your machine can have several network adaptors (ethernet boards, Wi-Fi, etc.), each configured with (numerous) routing setups, plus the routers they're connected to have their own routing setups... This can go on and on. As a last resort there are always OS specific APIs to iterate network interfaces. For example, for linux: http://man7.org/linux/man-pages/man3/getifaddrs.3.html (Of course this doesn't tell you at all whether a local IP-address is actually routable. And you probably have to figure out if you got a link local / ULA IPv6 or a global one)
Re: How can i find my LAN IP Address using std.socket?
On Tuesday, 4 February 2014 at 20:19:14 UTC, TheFlyingFiddle wrote: I'm setting up a simple local network enabling me to connect phones to the computer through the local wi-fi. The simplest way i could think of to make this work without relying on an external server was to simply broadcast the ip and port to all machines in the network.(Btw by server i mean my / my project groups windows boxes). So well the problem is that i need a way for the phones to find running servers on the LAN. I think it is close to impossible to do in portable way. Most reliable approach is to get list of all configured network interfaces via posix functions (or via `system` call as least resort), filter out lo and broadcast message for every such interface. I think you can also filter only wireless interfaces that way relatively easily too.
Re: Help with array maniipulation
Ali Çehreli: Is that the C extension where the last array in a struct can have more elements than its size? That will be a problem in D. Since V.2.065 D supports well variable-length structs. You have to use ubyte[0] data, and then allocate a large enough memory for the whole variable-length struct. Here I have written an usage example: http://rosettacode.org/wiki/Sokoban#Faster_Version Bye, bearophile
Re: What does the alias attribute do here
On Tuesday, 4 February 2014 at 17:17:13 UTC, Adam D. Ruppe wrote:
This specifically won't compile, alias params are only allowed
in a compile-time list. So
void foo(alias bar)() { ... }
would work.
[...]
Thanks, Adam, for the thorough explanation. This was quite
helpful for me as well.
Re: Performant method for reading huge text files
On Tuesday, 4 February 2014 at 00:04:23 UTC, Rene Zwanenburg wrote: On Monday, 3 February 2014 at 23:50:54 UTC, bearophile wrote: Rene Zwanenburg: The problem is speed. I'm using LockingTextReader in std.stdio, but it't not nearly fast enough. On my system it only reads about 3 MB/s with one core spending all it's time in IO calls. Are you reading the text by lines? In Bugzilla there is a byLineFast: https://d.puremagic.com/issues/show_bug.cgi?id=11810 Bye, bearophile Nope, I'm feeding it to csvReader which uses an input range of characters. Come to think of it.. Well this is embarassing, I've been sloppy with my profiling :). It appears the time is actually spent converting strings to doubles, done by csvReader to read a row into my Record struct. No way to speed that up I suppose. Still I find it surprising that parsing doubles is so slow. Parsing should be faster than I/O. Set up two buffers and have one thread reading into buffer A while you parse buffer B with a second thread.
Re: Performant method for reading huge text files
Parsing should be faster than I/O. Set up two buffers and have one thread reading into buffer A while you parse buffer B with a second thread. ...and then flip buffers whenever the slower of the two has completed.
