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digitalmars.D.learn - Invalid bounding interval [, ]

reply C <b_avic yahoo.com> writes:
I want to fill a ubyte array with random data.
The code compiles with no warnings or errors.

Source snippet:

        auto prng = Random(unpredictableSeed);
        ubyte[] chunk;

        chunk.length = 1024;

        fill(chunk, uniform!("[]")('\x00', '\xFF', prng));

Error (at runtime):

object.Exception c:\dmd2\windows\bin\..\..\src\phobos\std\random.d(971):
std.random.uniform(): invalid bounding interval [ ,  ]
----------------
423C50
423AC7
404EA8
404EEC
404AE3
4A6109
----------------

Also I lost the URL for this forum, all I see is this nasty PHP News Reader
interface.
Thank you.
Jan 24 2012
next sibling parent reply bearophile <bearophileHUGS lycos.com> writes:
C:


 I want to fill a ubyte array with random data.


In D ubytes are not char, they are two different types. So if you want ubytes,
then use ubytes:
uniform!("[]")(ubyte.min, ubyte.max)


Regarding your error, a reduced test case:

import std.random: uniform;
void main() {
    uniform!("[]")(char.min, char.max);
    uniform!("(]")(char.min, char.max);
}

Bye,
bearophile
Jan 24 2012
parent Timon Gehr <timon.gehr gmx.ch> writes:
On 01/25/2012 04:50 AM, bearophile wrote:

 C:


 I want to fill a ubyte array with random data.


 In D ubytes are not char, they are two different types. So if you want ubytes,
then use ubytes:
 uniform!("[]")(ubyte.min, ubyte.max)


 Regarding your error, a reduced test case:

 import std.random: uniform;
 void main() {
      uniform!("[]")(char.min, char.max);
      uniform!("(]")(char.min, char.max);
 }

 Bye,
 bearophile


Even more reduced test case and bug report:
http://d.puremagic.com/issues/show_bug.cgi?id=7367
Jan 24 2012
prev sibling next sibling parent reply Timon Gehr <timon.gehr gmx.ch> writes:
On 01/25/2012 04:25 AM, C wrote:

 I want to fill a ubyte array with random data.
 The code compiles with no warnings or errors.

 Source snippet:

          auto prng = Random(unpredictableSeed);
          ubyte[] chunk;

          chunk.length = 1024;

          fill(chunk, uniform!("[]")('\x00', '\xFF', prng));

 Error (at runtime):

 object.Exception c:\dmd2\windows\bin\..\..\src\phobos\std\random.d(971):
 std.random.uniform(): invalid bounding interval [ , �]
 ----------------
 423C50
 423AC7
 404EA8
 404EEC
 404AE3
 4A6109
 ----------------

 Also I lost the URL for this forum, all I see is this nasty PHP News Reader
 interface.
 Thank you.


The code wouldn't do what you intended even if it compiled. Use this:

auto chunk = new ubyte[1024];
foreach(ref x; chunk) x = uniform!"[]"(ubyte.min, ubyte.max);
Jan 24 2012
parent reply C <b_avic yahoo.com> writes:
 auto chunk = new ubyte[1024];
 foreach(ref x; chunk) x = uniform!"[]"(ubyte.min, ubyte.max);


Thank you all for your replies.

  Timon, I have two questions:
1) How come you can omit parentheses for uniform's parameter, shouldn't it be
 uniform!("[]")(...) ?
2) Does auto chunk = new ubyte[1024]; ALWAYS create a dynamic array with
changeable length?
That is a silly question but the syntax confuses me.
Jan 25 2012
parent Timon Gehr <timon.gehr gmx.ch> writes:
On 01/25/2012 12:28 PM, C wrote:

 auto chunk = new ubyte[1024];
 foreach(ref x; chunk) x = uniform!"[]"(ubyte.min, ubyte.max);


 Thank you all for your replies.

   Timon, I have two questions:
 1) How come you can omit parentheses for uniform's parameter, shouldn't it be
   uniform!("[]")(...) ?


If there is only one template argument, parentheses can be omitted.


 2) Does auto chunk = new ubyte[1024]; ALWAYS create a dynamic array with
 changeable length?
 That is a silly question but the syntax confuses me.


Yes it does. But this works too and is probably more intuitive if you 
are not familiar with other C-derived languages:

auto chunk = new ubyte[](1024);
Jan 25 2012
prev sibling parent Era Scarecrow <rtcvb32 yahoo.com> writes:
 1) How come you can omit parentheses for uniform's
 parameter, shouldn't it be
  uniform!("[]")(...) ?


 I think I can answer this.

 With ! already being used, it already knows it's a template and is separating
your argument. Being as you only have 1 argument, it's allowed. That's why you
can see to!string(x) and to!(string)(x).

 At least that's how I understand it. If you have more than 1 argument for your
template say for 'T2 fromTo(T, T2)(T t)', it has to be in parentheses. Not only
would something like 'fromTo!int!string(x)' be difficult to read (and ugly,
feels like :: for c++), it would probably be a pain on the compiler and syntax
checker. So the second one would be 'fromTo!(int, string)(x)'. Etc.

 A good number of things are syntactical sugar, making lives easier :)
Jan 25 2012