http://d.puremagic.com/issues/show_bug.cgi?id=10434

           Summary: Don't use Random as template parameter name in
                    std.random (or anywhere else)
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody@puremagic.com
        ReportedBy: joseph.wakeling@webdrake.net


--- Comment #0 from Joseph Rushton Wakeling <joseph.wakeling@webdrake.net> 2013-06-20 16:18:36 PDT ---
Quite a number of functions and objects in std.random use Random as the template parameter name for a random number generator -- e.g. in RandomCover:

    struct RandomCover(Range, Random)
        if(isRandomAccessRange!Range && isUniformRNG!Random)

This is obviously dangerous as it risks accidental confusion with the alias Random used for the default RNG type.

Elsewhere, the very long UniformRandomNumberGenerator is used as a typical parameter name -- descriptive but a pain to retype!

So, I suggest replacing these parameter name with something consistent and more appropriate -- either Rng (which is used in some other places in std.random) or RNG (which I prefer to Rng, but which maybe isn't in line with D style:-)

If there's a desire to stress that a parameter is a _uniform_ random number generator, we could also use Urng or URNG or even UniformRNG, but I think that's overkill as those features of the parameter should be indicated by template constraints, not naming conventions that are bordering on the Hungarian.

We could also take this opportunity to standardize the typical variable name for a RNG -- which in some places is called rnd, in some rng, in some urng, and in some gen.

So, I propose standardizing on RNG or Rng for template parameters (someone tell me which:-) and rng for variable names.

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |andrej.mitrovich@gmail.com


--- Comment #1 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-06-20 16:23:40 PDT ---
RandGen could also work.

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hsteoh@quickfur.ath.cx changed:

           What    |Removed                     |Added
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                 CC|                            |hsteoh@quickfur.ath.cx


--- Comment #2 from hsteoh@quickfur.ath.cx 2013-07-15 16:16:22 PDT ---
+1 for RandGen, self-documenting and doesn't clash with existing symbol. Rng is a bit obscure for those not in the know.

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--- Comment #3 from github-bugzilla@puremagic.com 2013-08-29 00:34:59 PDT ---
Commits pushed to master at https://github.com/D-Programming-Language/phobos

https://github.com/D-Programming-Language/phobos/commit/8d9233cf8b9e4d27bd70dd0fcd171d2f6dc2f2c0 Partial fix for Issues 7067 and 10434 - std.random.RandomCover

The existing RandomCover design is fatally flawed because it requires a RNG as input, which it then copies internally by value.  So, unless the user is smart enough to pass something like e.g. SomeRNG(unpredictableSeed), there will be unintended correlations in random behaviour.

This partial fix follows the design of RandomSample in allowing RandomCover to use the thread-global default RNG rndGen.  It also improves the choice of template parameter and variable names in line with Issue 10434.

https://github.com/D-Programming-Language/phobos/commit/2c9ecb8bd146a77c5ca450a69771b0d9dfcdf732 Partial fix for Issue 10434 - std.random.RandomSample

In line with changes to RandomCover, this patch tweaks
the choice of template parameter and variable names in
order to bring clarity and uniformity to the module.

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--- Comment #4 from Joseph Rushton Wakeling <joseph.wakeling@webdrake.net> 2013-08-30 03:02:56 PDT ---
(In reply to comment #2)
> +1 for RandGen, self-documenting and doesn't clash with existing symbol. Rng is a bit obscure for those not in the know.

If you look at the pull which has just landed, I settled on UniformRNG in order to match the isUniformRNG template, with RandomGen as a secondary choice.  I decided this was preferable since the uniformity of the generator _does_ matter.

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