• Johannes Loher (22/22) Feb 16 2016 Hello, I have a problem with using std.range.choose():
• Johannes Loher (4/12) Feb 20 2016 Well, has anybody got an idea if this behaviour is intended? Is
• =?UTF-8?Q?Ali_=c3=87ehreli?= (4/16) Feb 20 2016 Filed:

Johannes Loher <johannes.loher fg4f.de> writes:

Hello, I have a problem with using std.range.choose():

When using std.range.choose() on a range R, for which 
hasElaborateCopyConstructor!R is true, then a postblit for the 
result of std.range.choose() is created, which includes a call to 
R.__postblit(). However, hasElaborateCopyConstructor!R may be 
true, even if R does not define this(this), for example in the 
case that one of the members of R does so.

The example that I encountered (reduced to a minimum) was the the 
following:

import std.stdio : stdin;
import std.range: choose;

void main()
{
     ubyte[1][] secondRange;
     choose(true, stdin.byChunk(1), secondRange);
}

In this case File defines this(this), but ByChunk does not, so 
the above code does not compile.

I think what std.range.choose() does here is completely 
unnecessary: When the result of std.range.choose() gets copied, 
the underyling range gets copied, and if it implements postblit, 
it is automatically called. No need to call it explicitly, right?.

Johannes Loher <johannes.loher fg4f.de> writes:

On Wednesday, 17 February 2016 at 01:35:34 UTC, Johannes Loher 
wrote:
 Hello, I have a problem with using std.range.choose():

 When using std.range.choose() on a range R, for which 
 hasElaborateCopyConstructor!R is true, then a postblit for the 
 result of std.range.choose() is created, which includes a call 
 to R.__postblit(). However, hasElaborateCopyConstructor!R may 
 be true, even if R does not define this(this), for example in 
 the case that one of the members of R does so.

 [...]

Well, has anybody got an idea if this behaviour is intended? Is 
it a bug?

=?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:

On 02/20/2016 02:18 AM, Johannes Loher wrote:
 On Wednesday, 17 February 2016 at 01:35:34 UTC, Johannes Loher wrote:
 Hello, I have a problem with using std.range.choose():

 When using std.range.choose() on a range R, for which
 hasElaborateCopyConstructor!R is true, then a postblit for the result
 of std.range.choose() is created, which includes a call to
 R.__postblit(). However, hasElaborateCopyConstructor!R may be true,
 even if R does not define this(this), for example in the case that one
 of the members of R does so.

 [...]

 Well, has anybody got an idea if this behaviour is intended? Is it a bug?

Filed:

   https://issues.dlang.org/show_bug.cgi?id=15708

Ali