Re: How to make a Currency class from std.BigInt?
Thanks. Do I need to use rational fractions for the Currencies class?
Re: How to make a Currency class from std.BigInt?
On Saturday, 31 January 2015 at 15:02:09 UTC, Colin wrote: Maybe you can articulate it in one post what this class is trying to achieve? Maybe this? https://github.com/andersonpd/decimal/blob/master/decimal/bigfloat.d The main thing is not to lose currency in calculations that use arithmetic.
Re: Labels in struct
On Saturday, 31 January 2015 at 16:04:36 UTC, tcak wrote:
I do not have a big example in the end to show, but is there
any way to put labels into struct definitions?
struct CommunicationMessage{
char[2] signature;
mainData:
int info1;
int info2;
extraData:
ushort checksum;
content:
}
Example I defined something like above. I am using it as a base
structure, and don't know how long the content of message will
be. But I know that it will be at the end. I could use that
content label to find out about end of struct. But
unfortunately, it doesn't seem like it is supported.
I could say void* endOfStruct = struct + sizeof(struct), but
then struct wouldn't be self explanatory with that content
label at the end.
... **without** that content label ...
Re: Labels in struct
You could use a UDA like that, though getting the offset will be
a bit tricky.
The idea is to use some uda type, even plain string is good
enough, then use the __traits to find the first appearance of
that UDA in the object and return that offset.
Keep in mind that the @uda: syntax applies it to ALL following
members, it isn't really a label, but if we only look at the
first time it shows up we can kinda pretend it is one.
Here's an example:
struct Foo {
int b;
@(label_one): // offset 4
int c;
int d;
@(label_two): // offset 12
int e;
}
// get the offset of the label on a type, see below for usage
size_t offsetOf(T, string label)() {
foreach(memberName; __traits(allMembers, T)) {
foreach(attribute; __traits(getAttributes, __traits(getMember,
T, memberName))) {
static if(is(typeof(attribute) == string) attribute ==
label)
return __traits(getMember, T,
memberName).offsetof;
}
}
assert(0, no such label);
}
void main() {
// gives what we expect
pragma(msg, offsetOf!(Foo, label_one));
pragma(msg, offsetOf!(Foo, label_two));
}
Re: Labels in struct
Oh this hack also won't work with a label at the very end. You could use sizeof for that though (however that would include padding bytes. Perhaps last member's offsetof plus last member's sizeof is a bit more accurate.)
Re: How to make a Currency class from std.BigInt?
The next version, which does not work: https://bpaste.net/show/b9c85de68d07
Re: How to make a Currency class from std.BigInt?
On 31.01.15 15:45, RuZzz wrote: Maybe I need good examples on C++, for this class, because a lot of examples on C++. Maybe this can help you: https://github.com/andersonpd/decimal
Re: How to make a Currency class from std.BigInt?
I want to understand the correct architecture of the class.
Re: How to make a Currency class from std.BigInt?
On Saturday, 31 January 2015 at 13:45:22 UTC, RuZzz wrote: I want to understand the correct architecture of the class. Sorry, you still did not state your problem (or what you are trying to achieve) clearly. Writing down a clear problem description is likely to get you halfway to the solution.
Error when profiling
When trying to run my program with profiling enabled it dies before the first line of my main function runs. Everything works fine without profiling. I get the following stack trace: thread #1: tid = 0x38de4, 0x00010008d985 vision_entry`gc_malloc + 49, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x0) frame #0: 0x00010008d985 vision_entry`gc_malloc + 49 vision_entry`gc_malloc + 49: - 0x10008d985: movq (%rdi), %rbx 0x10008d988: callq *0x60(%rbx) 0x10008d98c: popq %rbx 0x10008d98d: movq %rbp, %rsp (lldb) thread backtrace * thread #1: tid = 0x38de4, 0x00010008d985 vision_entry`gc_malloc + 49, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x0) * frame #0: 0x00010008d985 vision_entry`gc_malloc + 49 frame #1: 0x0001000908f5 vision_entry`_d_newclass + 117 frame #2: 0x0001000b4b28 vision_entry`D3std9exception7bailOutFNaNfAyamxAaZv + 40 frame #3: 0x0001000b4d06 vision_entry`D3std9exception14__T7enforceTbZ7enforceFNaNfbLAxaAyamZb + 94 frame #4: 0x0001000c4df6 vision_entry`D3std5stdio4File17LockingTextWriter6__ctorMFNcNeKS3std5stdio4FileZS3std5stdio4File17LockingTextWriter + 86 frame #5: 0x0001000c4f19 vision_entry`D3std5stdio4File17lockingTextWriterMFZS3std5stdio4File17LockingTextWriter + 41 frame #6: 0x00012c74 vision_entry`D3std5stdio4File15__T8writeflnTaZ8writeflnMFxAaZv + 124 at stdio.d:1238 frame #7: 0x00010c06 vision_entry`_Dmain + 86 at stdio.d:2727 frame #8: 0x00010009060c vision_entry`D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZ9__lambda1MFZv + 40 frame #9: 0x000100090551 vision_entry`D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ7tryExecMFMDFZvZv + 45 frame #10: 0x0001000905b1 vision_entry`D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZv + 45 frame #11: 0x000100090551 vision_entry`D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ7tryExecMFMDFZvZv + 45 frame #12: 0x0001000904cd vision_entry`_d_run_main + 433 frame #13: 0x00010d29 vision_entry`main + 65 frame #14: 0x7fff883a45c9 libdyld.dylib`start + 1 Does anyone have any ideas of what could have caused this?
Re: How to make a Currency class from std.BigInt?
On 31.01.15 15:56, zeljkog wrote: On 31.01.15 15:45, RuZzz wrote: Maybe I need good examples on C++, for this class, because a lot of examples on C++. Maybe this can help you: https://github.com/andersonpd/decimal Also http://code.dlang.org/packages/eris
Labels in struct
I do not have a big example in the end to show, but is there any
way to put labels into struct definitions?
struct CommunicationMessage{
char[2] signature;
mainData:
int info1;
int info2;
extraData:
ushort checksum;
content:
}
Example I defined something like above. I am using it as a base
structure, and don't know how long the content of message will
be. But I know that it will be at the end. I could use that
content label to find out about end of struct. But
unfortunately, it doesn't seem like it is supported.
I could say void* endOfStruct = struct + sizeof(struct), but
then struct wouldn't be self explanatory with that content label
at the end.
Re: How to make a Currency class from std.BigInt?
Maybe I need good examples on C++, for this class, because a lot of examples on C++.
Re: How to make a Currency class from std.BigInt?
I am looking for not only free solutions.
Re: How to make a Currency class from std.BigInt?
On Saturday, 31 January 2015 at 14:26:45 UTC, RuZzz wrote: The next version, which does not work: https://bpaste.net/show/b9c85de68d07 I really dont understand what your trying to achieve here. Maybe you can articulate it in one post what this class is trying to achieve?
Re: Labels in struct
On 01/31/15 17:04, tcak via Digitalmars-d-learn wrote:
struct CommunicationMessage{
[...]
content:
}
Example I defined something like above. I am using it as a base structure,
and don't know how long the content of message will be. But I know that it
will be at the end. I could use that content label to find out about end of
struct. But unfortunately, it doesn't seem like it is supported.
I could say void* endOfStruct = struct + sizeof(struct), but then struct
wouldn't be self explanatory with that content label at the end.
The traditional way (ie C-like) would be
ubyte[0] content; // zero-sized; use casts etc to access data.
as the last member. D supports that too, and just like
many other D features it works for ~80% of cases. IOW
you should be able to get it to work, but you might run
into problems if you need to access/manipulate such types.
artur
Re: Labels in struct
On 31.01.15 17:04, tcak wrote:
I do not have a big example in the end to show, but is there any way to
put labels into struct definitions?
struct CommunicationMessage{
char[2] signature;
mainData:
int info1;
int info2;
extraData:
ushort checksum;
content:
}
Members of type struct are actualy labels.
struct CommunicationMessage{
struct Md {
int info1;
int info2;
};
struct Ed {
ushort checksum;
}
struct Cnt {
}
char[2] signature;
Md mainData;
Ed extraData;
Cnt content;
}
Re: How to make a Currency class from std.BigInt?
The next version https://bpaste.net/show/9468f24d9df0
Re: foreach - premature optimization vs cultivating good habits
On Friday, 30 January 2015 at 14:41:11 UTC, Laeeth Isharc wrote: Thanks, Adam. That's what I had thought (your first paragraph), but something Ola on a different thread confused me and made me think I didn't understand it, and I wanted to pin it down. There is always significant optimization effects in long running loops: - SIMD - cache locality / prefetching For the former (SIMD) you need to make sure that good code is generated either by hand, by using vectorized libraries or by auto vectorization. For the latter (cache) you need to make sure that the prefetcher is able to predict or is being told to prefetch explicitly and also that the working set is small enough to stay at the faster cache levels. If you want good performance you cannot ignore any of these, and you have to design the data structures and algorithms for it. Prefetching has to happen maybe 100 instructions before the actual load from memory and AVX requires byte alignment and a layout that fits the algorithm. On next gen Xeon Skylake I think the alignment might go up to 64 byte and you have 512 bits wide registers (so you can do 8 64 bit floating point operations in parallel per core). The difference between issuing 1-4 ops and issuing 8-16 per time unit is noticable... An of course, the closer your code is to theoretical throughput in the CPU, the more critical it becomes to not wait for memory loads. This is also a moving target...
windows wininet library
how can i use wininet.dll from D? i got bindings from https://github.com/ CS-svnmirror/dsource-bindings-win32.git, and then i tried to create wininet.lib with implib.exe from DMC package. no matter how i tried, the resulting wininet.lib seems to not work, as linker keep complaining about missing symbols like _InternetReadFile@16 and so on. i'm building for win32. ah, and yep, i compiled wininet.lib to lib dir, and added option to dmd.exe: -L+wininet.lib. i assume that i have to create corrent .def file to remap all the names, am i right? oh, delightful... signature.asc Description: PGP signature
Re: How to make a Currency class from std.BigInt?
How to get amount of digit after point in a double for to get integer from a double? assert(amountAfterPoint(1.456) == 3); assert(amountAfterPoint(0.6) == 5);
Re: How to make a Currency class from std.BigInt?
without to!string
Re: How to make a Currency class from std.BigInt?
On Saturday, 31 January 2015 at 12:07:23 UTC, RuZzz wrote:
How to get amount of digit after point in a double for to get
integer from a double?
assert(amountAfterPoint(1.456) == 3);
assert(amountAfterPoint(0.6) == 5);
How about a loop like
import std.stdio;
void main(){
writefln(%s, 1.45.numDigits);// prints 2
writefln(%s, 1.452343.numDigits);// prints 6
writefln(%s, 1.0.numDigits);// prints 0
}
long numDigits(double num){
long i=0;
double n=num;
while(true){
if(n - (cast(long)n) == 0){
return i;
}
i++;
n *= 10;
}
}
