digitalmars.D.learn - ubyte[] -> immutable(ubyte)[]

Andrej Mitrovic (35/35) Sep 03 2010 This is from TDPL page 407:

Andrej Mitrovic (28/73) Sep 09 2010 I'm trying to use algorithm.copy, but I get back nothing in the copy bu...

bearophile (4/5) Sep 09 2010 a[] = b[];

Andrej Mitrovic (2/9) Sep 10 2010 No, that wouldn't work. It complains about conversion from mutable to im...

Kagamin (4/13) Sep 09 2010 Isn't destination the left argument?

Andrej Mitrovic (2/17) Sep 10 2010

vino (61/80) May 03 2016 Hi Andrei/All,

Steven Schveighoffer (8/79) May 04 2016 buffer.idup turns into immutable(ubyte)[]. You must receive this type:

Pelle (9/80) Sep 10 2010 std.algorithm.copy will copy an input range into an output range. An

Andrej Mitrovic (2/13) Sep 10 2010

Andrej Mitrovic <andrej.mitrovich test.com> writes:

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?

Sep 03 2010

Andrej Mitrovic <test test.test> writes:

 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?

Sep 09 2010

bearophile <bearophileHUGS lycos.com> writes:

Andrej Mitrovic:
  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?

a[] = b[];

Bye,
bearophile

Sep 09 2010

Andrej Mitrovic <test test.test> writes:

bearophile Wrote:

 Andrej Mitrovic:
  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?

 
 a[] = b[];
 
 Bye,
 bearophile

No, that wouldn't work. It complains about conversion from mutable to
immutable. idup works fine though.

Sep 10 2010

Kagamin <spam here.lot> writes:

Andrej Mitrovic Wrote:

     foreach (ubyte[] buffer; stdin.byChunk(bufferSize))
     {
         immutable(ubyte)[] copy_buffer;
         copy(buffer, copy_buffer);
         
         writeln(copy_buffer);  // writes nothing
 
         send(tid, copy_buffer);
     }

Isn't destination the left argument?
Why you don't use send(tid, buffer.idup);
?

Sep 09 2010

Andrej Mitrovic <test test.test> writes:

Yeah, one would think the destination is on the left (just like the standard C
way of doing it), but it's not. I checked it in the docs and the source. And
idup works, thanks.

Kagamin Wrote:

 Andrej Mitrovic Wrote:
 
     foreach (ubyte[] buffer; stdin.byChunk(bufferSize))
     {
         immutable(ubyte)[] copy_buffer;
         copy(buffer, copy_buffer);
         
         writeln(copy_buffer);  // writes nothing
 
         send(tid, copy_buffer);
     }

 
 Isn't destination the left argument?
 Why you don't use send(tid, buffer.idup);
 ?

Sep 10 2010

vino <vino_ss hotmail.com> writes:

On Friday, 10 September 2010 at 15:15:38 UTC, Andrej Mitrovic 
wrote:
 Yeah, one would think the destination is on the left (just like 
 the standard C way of doing it), but it's not. I checked it in 
 the docs and the source. And idup works, thanks.

 Kagamin Wrote:

 Andrej Mitrovic Wrote:
 
     foreach (ubyte[] buffer; stdin.byChunk(bufferSize))
     {
         immutable(ubyte)[] copy_buffer;
         copy(buffer, copy_buffer);
 
         writeln(copy_buffer);  // writes nothing
 
         send(tid, copy_buffer);
     }

 
 Isn't destination the left argument?
 Why you don't use send(tid, buffer.idup);
 ?


Hi Andrei/All,

  Request your help, I am trying the program written by you with 
few changes such as the example program read the input from stdin 
and prints the data to stdout, but my program reads the input 
from the file(readfile.txt) and writes the output to another 
file(writefile.txt), and I am getting the below errors while 
compiling

Testing:
Read a file(readfile.txt : Contain 20,000 lines) by chunk into a 
buffer(read buffer)
Pass the buffered data to an output buffer(write buffer) and then 
write the output buffer to a to another file(writefile.txt).
Error:


readwriteb.d(7): Error: cannot implicitly convert expression 
(__aggr2859.front()) of type ubyte[] to immutable(ubyte)[]
readwriteb.d(15): Error: cannot implicitly convert expression 
(receiveOnly()) of type immutable(ubyte)[] to 
std.outbuffer.OutBuffer


Version: DMD64 D Compiler v2.071.0

Code:

import std.algorithm, std.concurrency, std.stdio, std.outbuffer, 
std.file;

void main() {
    enum bufferSize = 1024 * 100;
    auto file = File("readfile.txt", "r");
    auto tid = spawn(&fileWriter);
    foreach (immutable(ubyte)[] buffer; file.byChunk(bufferSize)) {
       send(tid, buffer);
    }
}

void fileWriter() {
    auto wbuf  = new OutBuffer();
    for (;;) {
       wbuf = receiveOnly!(immutable(ubyte)[])();
       write("writefile.txt", wbuf);
    }
}

After few changes as below I was able to compile, but when i run 
the program there is no data in the writefile.txt

import std.algorithm, std.concurrency, std.stdio, std.file;

void main() {
    enum bufferSize = 1024 * 100;
    auto file = File("readfile.txt", "r");
    auto tid = spawn(&fileWriter);
    foreach (ubyte[] buffer; file.byChunk(bufferSize)) {
       send(tid, buffer.idup);
    }
}

void fileWriter() {
auto file = File("writefile.txt", "w");
for (;;) {
      auto  wbuf = receiveOnly!(ubyte[])();
       file.writeln("writefile.txt", wbuf);
    }
}

From,
Vino.B

May 03 2016

Steven Schveighoffer <schveiguy yahoo.com> writes:

On 5/3/16 5:31 PM, vino wrote:
 On Friday, 10 September 2010 at 15:15:38 UTC, Andrej Mitrovic wrote:
 Yeah, one would think the destination is on the left (just like the
 standard C way of doing it), but it's not. I checked it in the docs
 and the source. And idup works, thanks.

 Kagamin Wrote:

 Andrej Mitrovic Wrote:

     foreach (ubyte[] buffer; stdin.byChunk(bufferSize))
     {
         immutable(ubyte)[] copy_buffer;
         copy(buffer, copy_buffer);
         writeln(copy_buffer);  // writes nothing
         send(tid, copy_buffer);

     }

 Isn't destination the left argument?
 Why you don't use send(tid, buffer.idup);
 ?


 Hi Andrei/All,

   Request your help, I am trying the program written by you with few
 changes such as the example program read the input from stdin and prints
 the data to stdout, but my program reads the input from the
 file(readfile.txt) and writes the output to another file(writefile.txt),
 and I am getting the below errors while compiling

 Testing:
 Read a file(readfile.txt : Contain 20,000 lines) by chunk into a
 buffer(read buffer)
 Pass the buffered data to an output buffer(write buffer) and then write
 the output buffer to a to another file(writefile.txt).
 Error:


 readwriteb.d(7): Error: cannot implicitly convert expression
 (__aggr2859.front()) of type ubyte[] to immutable(ubyte)[]
 readwriteb.d(15): Error: cannot implicitly convert expression
 (receiveOnly()) of type immutable(ubyte)[] to std.outbuffer.OutBuffer


 Version: DMD64 D Compiler v2.071.0

 Code:

 import std.algorithm, std.concurrency, std.stdio, std.outbuffer, std.file;

 void main() {
     enum bufferSize = 1024 * 100;
     auto file = File("readfile.txt", "r");
     auto tid = spawn(&fileWriter);
     foreach (immutable(ubyte)[] buffer; file.byChunk(bufferSize)) {
        send(tid, buffer);
     }
 }

 void fileWriter() {
     auto wbuf  = new OutBuffer();
     for (;;) {
        wbuf = receiveOnly!(immutable(ubyte)[])();
        write("writefile.txt", wbuf);
     }
 }

 After few changes as below I was able to compile, but when i run the
 program there is no data in the writefile.txt

 import std.algorithm, std.concurrency, std.stdio, std.file;

 void main() {
     enum bufferSize = 1024 * 100;
     auto file = File("readfile.txt", "r");
     auto tid = spawn(&fileWriter);
     foreach (ubyte[] buffer; file.byChunk(bufferSize)) {
        send(tid, buffer.idup);
     }
 }

 void fileWriter() {
 auto file = File("writefile.txt", "w");
 for (;;) {
       auto  wbuf = receiveOnly!(ubyte[])();

buffer.idup turns into immutable(ubyte)[]. You must receive this type:

auto wbuf = receiveOnly!(immutable(ubyte)[])();

What is likely happening is that this receiveOnly throws an exception 
you aren't catching, and then the program hangs. Try catching any 
errors/exceptions in your fileWriter thread function and print them out 
to see what is really happening.

-Steve

May 04 2016

Pelle <pelle.mansson gmail.com> writes:

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; :-)

Sep 10 2010

Andrej Mitrovic <test test.test> writes:

Ah, idup. Too obvious, but I missed it. Thanks.

Pelle Wrote:

 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; :-)

Sep 10 2010

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