ubyte[] -> immutable(ubyte)[]
Pelle
pelle.mansson at gmail.com
Fri Sep 10 04:08:10 PDT 2010
On 09/10/2010 04:40 AM, Andrej Mitrovic wrote:
> I'm trying to use algorithm.copy, but I get back nothing in the copy buffer. How do I to copy an array of ubyte's?
>
> iimport std.algorithm,
> std.concurrency,
> std.stdio;
>
> void main()
> {
> enum bufferSize = 4;
> auto tid = spawn(&fileWriter);
>
> // Read loop
> foreach (ubyte[] buffer; stdin.byChunk(bufferSize))
> {
> immutable(ubyte)[] copy_buffer;
> copy(buffer, copy_buffer);
>
> writeln(copy_buffer); // writes nothing
>
> send(tid, copy_buffer);
> }
> }
>
> void fileWriter()
> {
> while (true)
> {
> auto buffer = receiveOnly!(immutable(ubyte)[])();
> // writeln(buffer);
> }
> }
>
> Andrej Mitrovic Wrote:
>
>> This is from TDPL page 407:
>>
>> import std.algorithm,
>> std.concurrency,
>> std.stdio;
>>
>> void main()
>> {
>> enum bufferSize = 1024 * 100;
>> auto tid = spawn(&fileWriter);
>>
>> // Read loop
>> foreach (immutable(ubyte)[] buffer; stdin.byChunk(bufferSize))
>> {
>> send(tid, buffer);
>> }
>> }
>>
>> void fileWriter()
>> {
>> // write loop
>> while (true)
>> {
>> auto buffer = receiveOnly!(immutable(ubyte)[])();
>> tgt.write(buffer);
>> }
>> }
>>
>> Error:
>> C:\DMD\dmd2\windows\bin\..\..\src\phobos\std\stdio.d(1943):
>> Error: cannot implicitly convert expression (buffer) of type ubyte[]
>> to immutable(ubyte)[]
>>
>> Yet interestingly I can't use type inference:
>>
>> foreach (buffer; stdin.byChunk(bufferSize))
>> {
>> send(tid, buffer);
>> }
>>
>> Error: stdin_stdout_copy.d(11): Error: cannot infer type for buffer
>>
>> But in the original code I get back a mutable ubyte[] which I can't implicitly convert to immutable (I'd need a copy first). There's no .dup or .idup property for stdin.byChunk. So what am I supossed to do here?
>>
>>
>
std.algorithm.copy will copy an input range into an output range. An
array is a valid output range, but does not append as you seem to
expect. Instead, it fills the array.
int[] a = new int[](3);
copy([1,2,3],a);
assert (a == [1,2,3]);
To get an output range which appends to an array, use appender.
In this case, however, you simply want buffer.idup; :-)
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