Re: Passing Templated Function Arguments Solely by Reference
On Friday, 11 July 2014 at 17:43:53 UTC, Ali Çehreli wrote: Ali Thx
Re: Passing Templated Function Arguments Solely by Reference
On Wednesday, 9 July 2014 at 07:43:57 UTC, Ali Çehreli wrote: Phobos algorithms use ranges. The following is what I've come up with very quickly: Thx
Re: Passing Templated Function Arguments Solely by Reference
On Wednesday, 9 July 2014 at 07:43:57 UTC, Ali Çehreli wrote: Ali This https://github.com/nordlow/justd/blob/master/random_ex.d is what I have so far. Does this look ok to you? Question: Can I somehow avoid the duplication of logic in - auto ref randInPlace(R)(R x) @safe if (hasAssignableElements!R) - auto ref randInPlace(T)(ref T x) @safe if (isStaticArray!T) ?
Re: Passing Templated Function Arguments Solely by Reference
On 07/11/2014 03:38 AM, Nordlöw wrote:
https://github.com/nordlow/justd/blob/master/random_ex.d
is what I have so far. Does this look ok to you?
The following seems redundant because the other isFloatingPoint!E
version uses the default arguments 0 and 1 anyway.
auto ref randInPlace(E)(ref E x) @trusted if (isFloatingPoint!E)
{
return x = uniform(cast(E)0,
cast(E)1);
}
Question: Can I somehow avoid the duplication of logic in
- auto ref randInPlace(R)(R x) @safe if (hasAssignableElements!R)
- auto ref randInPlace(T)(ref T x) @safe if (isStaticArray!T)
The following works if you pardon the name foo. :p
auto foo(TT)(ref TT x)
{
foreach (ref e; x)
{
e.randInPlace;
}
return x;
}
/** Generate Random Contents in $(D x).
*/
auto ref randInPlace(R)(auto ref R x) @safe if (hasAssignableElements!R)
{
return foo(x);
}
/** Generate Random Contents in $(D x).
*/
auto ref randInPlace(T)(ref T x) @safe if (isStaticArray!T)
{
return foo(x);
}
Alternatively, a string mixin could be used but they should be reserved
for when there is no better solution.
Ali
Re: Passing Templated Function Arguments Solely by Reference
On 07/08/2014 05:13 PM, Nordlöw wrote:
If I want randInPlace to take value arguments (such as structs) by
reference and reference types (classes) as normal is this
I don't understand what it means to fill a struct or a class object with
random content.
/** Generate Random Contents in $(D x).
*/
auto ref randInPlace(T)(auto ref T x) @safe /* nothrow */ if
(isIterable!T)
hasAssignableElements is more correct.
{
foreach (ref elt; x)
{
import std.range: ElementType;
static if (isInputRange!(ElementType!T))
The documentation of hasAssignableElements mentions that it implies
isForwardRange and it makes sense: You don't want the range to be
consumed as an InputRange would do.
elt[].randInPlace;
else
elt.randInPlace;
}
return x;
}
And how does this compare to using x[].randInPlace() when x is a static
array?
Range algorithms don't work with static arrays because they can't
popFront(). The solution is to use a slice to the entire array as you've
already done as x[]. ;)
Does x[] create unnecessary GC-heap activity in this case?
No. Static array will remain in memory and x[] will be a local slice. A
slice consists of two members, the equivalent of the following:
struct __SliceImpl
{
size_t length;
void * pointer_to_first_element;
}
I'm wondering because (auto ref T x) is just used in two places in
std.algorithm and std.range in Phobos. Is this a relatively new
enhancement?
Phobos algorithms use ranges. The following is what I've come up with
very quickly:
import std.stdio;
import std.range;
import std.traits;
import std.random;
void randInPlace(R)(R range)
if (hasAssignableElements!R)
{
foreach (ref e; range) {
e.randInPlace();
}
}
void randInPlace(E)(ref E element)
if (isNumeric!E)
{
// BUG: Never assigns the value E.max
element = uniform(E.min, E.max);
}
void randInPlace(E)(ref E element)
if (isBoolean!E)
{
element = cast(bool)uniform(0, 2);
}
void main()
{
auto arr = [ [ 0, 1, 2 ], [ 3, 4, 5 ] ];
arr.randInPlace();
writefln(%s, arr);
auto barr = [ [ false, true ], [ false, true ] ];
barr.randInPlace();
writefln(%s, barr);
}
Ali
Re: Passing Templated Function Arguments Solely by Reference
On Wednesday, 9 July 2014 at 00:13:41 UTC, Nordlöw wrote: Searching for Function Templates with Auto Ref Parameters on http://dlang.org/template.html answered my first question. I'm however still uncertain how to implement randInPlace in the most D idiomatic way.
