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enhancement issue 4851: use assert in choice function

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This commit is contained in:
Eduard Staniloiu 2016-11-14 14:01:52 +02:00
parent 783d15bfa0
commit adb71a6c6b
1 changed files with 13 additions and 15 deletions
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24
std/random.d
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@ -1807,31 +1807,28 @@ F[] uniformDistribution(F = double)(size_t n, F[] useThis = null)
} }
/** /**
Returns a random, uniformly chosen, element $(D e) from the supplied Returns a random, uniformly chosen, element `e` from the supplied
$(D Range range). If no random number generator is passed, the default $(D Range range). If no random number generator is passed, the default
$(D rndGen) is used. `rndGen` is used.
Params: Params:
range = a random access range that has the length property defined range = a random access range that has the `length` property defined
urng = (optional) random number generator to use; urng = (optional) random number generator to use;
if not specified, defaults to $(D rndGen) if not specified, defaults to `rndGen`
Returns: Returns:
A single random element drawn from the $(D range). If it can, it will A single random element drawn from the `range`. If it can, it will
return a $(D ref) to the $(D range element), otherwise it will return return a `ref` to the $(D range element), otherwise it will return
a copy. a copy.
*/ */
auto ref choice(Range, RandomGen = Random)(auto ref Range range, auto ref choice(Range, RandomGen = Random)(auto ref Range range,
ref RandomGen urng = rndGen) ref RandomGen urng = rndGen)
if (isRandomAccessRange!Range && hasLength!Range && isUniformRNG!RandomGen) if (isRandomAccessRange!Range && hasLength!Range && isUniformRNG!RandomGen)
{ {
import std.conv : to, text; assert(range.length > 0,
import std.exception : enforce; __PRETTY_FUNCTION__ ~ ": invalid Range supplied. Range cannot be empty");
enforce(range.length > 0, return range[uniform(size_t(0), $, urng)];
text("std.random.choice(): invalid Range supplied. Range cannot be empty"));
return range[uniform(to!size_t(0), $, urng)];
} }
/// ///
@ -1867,7 +1864,8 @@ auto ref choice(Range, RandomGen=Random)(auto ref Range range,
} }
MyTestClass[] testClass; MyTestClass[] testClass;
foreach(i; 0 .. 5) { foreach(i; 0 .. 5)
{
testClass ~= new MyTestClass(i); testClass ~= new MyTestClass(i);
} }