Video playback
Hi everyone! I want to play video in my D-application (maybe WebM or Theora). However didn't find any library for operation with video in D. I am a beginner in D, experience of transfer of libraries with C/C++, certainly isn't present. Maybe somebody will prompt something? P.S. My application uses SFML (DSFML).
Re: randomSample
Meta:
You need to use the function array from std.array.
import std.array;
int[] source = [ ... ];
int[] sample = randomSample(source, 3).array();
In some cases it's also useful to use std.algorithm.copy:
void main() {
import std.stdio, std.algorithm, std.random, std.array,
std.range;
immutable int[9] source = iota(10, 100, 10).array;
source.writeln;
int[3] sample;
source[].randomSample(sample.length).copy(sample[]);
sample.writeln;
}
Bye,
bearophile
Re: Video playback
On 18/05/2014 7:10 p.m., Dmitry wrote: Hi everyone! I want to play video in my D-application (maybe WebM or Theora). However didn't find any library for operation with video in D. I am a beginner in D, experience of transfer of libraries with C/C++, certainly isn't present. Maybe somebody will prompt something? P.S. My application uses SFML (DSFML). My suggestion would be to go the direction of libvlc[0]. I did find a forum post from SFML that may help you. It is a c library so it shouldn't be too hard to create a binding to. Perhaps something along the lines of Derelict-Util[2] will help with it. If you need shared libraries and don't want to build your own, you should be able to extract them after installing Vlc itself. [0] https://wiki.videolan.org/LibVLC/ [1] http://en.sfml-dev.org/forums/index.php?topic=9386.0 [2] https://github.com/DerelictOrg/DerelictUtil
UCFS does not work for nested functions?
Hi,
Just noticed that using UFCS does not work for nested functions,
and was wondering whether that's intended, and what the rationale
behind it is:
class X {
void foo() {}
}
void main() {
// moving bar to module scope solves the error below
void bar(X x) {}
X x;
x.foo(); // ok
bar(x); // ok
x.bar(); // Error: no property 'bar' for type 'nested.X'
}
Re: UCFS does not work for nested functions?
Steffen Wenz: Just noticed that using UFCS does not work for nested functions, Right. and was wondering whether that's intended, and what the rationale behind it is: Currently it's intended. Because doing otherwise causes other problems with struct/class member functions. Perhaps there are ways to design around this problem, but so far no one has suggested a good way to design it (and the good Kenji has worked on this problem, so probably there are no simple solutions). Once you understand this problem space well, if you find a good design solution you can submit it to Bugzilla. Bye, bearophile
Re: Problems with dmd Switches in Makefiles
For the compiler version, I've submitted a PR: https://github.com/D-Programming-Language/dmd/pull/3558
Re: Video playback
On Sunday, 18 May 2014 at 07:37:33 UTC, Rikki Cattermole wrote: My suggestion would be to go the direction of libvlc[0]. I did find a forum post from SFML that may help you. It is a c library so it shouldn't be too hard to create a binding to. Perhaps something along the lines of Derelict-Util[2] will help with it. If you need shared libraries and don't want to build your own, you should be able to extract them after installing Vlc itself. Thank you, Rikki! I try.
Modify char in string
Hi everyone,
is there any chance to modify a char in a string like:
void main()
{
string sMyText = "Replace the last char_";
sMyText[$ - 1] = '.';
}
But when I execute the code above I'm always getting "cannot
modify immutable expression at sMyText[__dollar -1LU]". I though
D supported such modifications anytime. How can I do that now...?
Re: Modify char in string
Tim:
is there any chance to modify a char in a string like:
void main()
{
string sMyText = "Replace the last char_";
sMyText[$ - 1] = '.';
}
But when I execute the code above I'm always getting "cannot
modify immutable expression at sMyText[__dollar -1LU]". I
though D supported such modifications anytime. How can I do
that now...?
D strings are immutable. And mutating immutable variables is a
bug in D. So you can't do that. You have to work around the
problem. One solution is to not have a string, but something more
like a char[] in the first place, and mutate it.
If you have a string, you can do (this works with the current GIT
DMD compiler):
/// Not Unicode-safe.
string dotLast(in string s) pure nothrow {
auto ds = s.dup;
ds[$ - 1] = '.';
return ds;
}
void main() {
import std.stdio;
immutable input = "Replace the last char_";
immutable result = input.dotLast;
result.writeln;
}
That code doesn't work if your text contains more than the Ascii
chars.
Bye,
bearophile
Re: Modify char in string
On Sunday, 18 May 2014 at 18:55:59 UTC, Tim wrote:
Hi everyone,
is there any chance to modify a char in a string like:
As you've seen, you cannot modify immutables (string is an
immutable(char)[]). If you actually do want the string to be
modifiable, you should define it as char[] instead.
Then your example will work:
void main()
{
char[] sMyText = "Replace the last char_";
sMyText[$ - 1] = '.';
}
If you actually want it to be immutable, you can still do it, but
you can't modify in-place, you must create a new string that
looks like what you want:
void main()
{
string sMyText = "Replace the last char_";
sMyText = sMyText[0 .. $-1] ~ ".";
// you would do
//sMyText[0 .. 5] ~ "." ~ sMyText[6..$];
// to "replace" something in the 5th position
}
Note that the second method allocates and uses the GC more (which
is perfectly fine, but not something you want to do in a tight
loop). For most circumstances, the second method is good.
Is it possible to assumeSafeAppend malloced memory?
We know that most of the time memory is allocated more than the
requested amount. Is there a way to take advantage of that extra
trailing space? (And potentially the pages that come after that.)
import core.memory;
void main()
{
const count = 1;
// I think there is extra capacity beyond the 'count' elements
int* ptr = cast(int*)GC.malloc(count * int.sizeof);
int[] arr = ptr[0 .. count];
assert(arr.capacity == 0);
arr.assumeSafeAppend;
assert(arr.capacity == 0);// still 0. :(
}
This issue puts std.array.array to a disadvantage compared to proper
slices because array() involves the following call chain, the last of
which does call GC.malloc:
trustedAllocateArray
uninitializedArray
arrayAllocImpl
As a result, iota(10).array.assumeSafeAppend ends up having 0 capacity. :(
Ali
