[PATCH] D37417: Add range based wrapper around std::for_each.

[David Blaikie via llvm-commits]

Not sure I follow - you have to write the type name in the parameter or in
the range-based-for, similar mistakes in either case, right?

On Mon, Sep 4, 2017 at 5:50 PM Keith Wyss <wyssman at gmail.com> wrote:

> I like for_each because it offers one less place to mistakenly capture by
> value.
>
> On Sep 4, 2017 1:22 PM, "David Blaikie" <dblaikie at gmail.com> wrote:
>
>>
>>
>> On Mon, Sep 4, 2017 at 1:16 PM Keith Wyss <wyssman at gmail.com> wrote:
>>
>>> It is an equivalent concept to range based for loop. Its not strictly
>>> necessary, but neither is std::for_each.
>>>
>>
>> Right - but std::for_each existed before the range based for loop (&
>> admittedly, before lambdas too). I'm not sure of the motivation for this
>> given C++11 features/today's code.
>>
>>
>>>
>>> On Sep 4, 2017 9:20 AM, "David Blaikie" <dblaikie at gmail.com> wrote:
>>>
>>>> What use case do you have for this over a range-based-for loop?
>>>>
>>>> On Sat, Sep 2, 2017 at 6:08 PM Keith via Phabricator via llvm-commits <
>>>> llvm-commits at lists.llvm.org> wrote:
>>>>
>>>>> kpw created this revision.
>>>>>
>>>>> There are a few range based wrappers llvm provides already. They're
>>>>> handy and I
>>>>> couldn't find one for std::for_each, so I'm adding it.
>>>>>
>>>>>
>>>>> https://reviews.llvm.org/D37417
>>>>>
>>>>> Files:
>>>>>   include/llvm/ADT/STLExtras.h
>>>>>   unittests/ADT/STLExtrasTest.cpp
>>>>>
>>>>>
>>>>> Index: unittests/ADT/STLExtrasTest.cpp
>>>>> ===================================================================
>>>>> --- unittests/ADT/STLExtrasTest.cpp
>>>>> +++ unittests/ADT/STLExtrasTest.cpp
>>>>> @@ -318,4 +318,14 @@
>>>>>    EXPECT_EQ(7, V[3]);
>>>>>  }
>>>>>
>>>>> +TEST(STLExtrasTest, ForEach) {
>>>>> +  std::vector<std::pair<int, int>> V = {{1, 2}, {3, 4}, {5, 6}};
>>>>> +  std::vector<int> Evens{};
>>>>> +  auto BackInserter = std::back_inserter(Evens);
>>>>> +  for_each(V,
>>>>> +           [&](std::pair<int, int> Element) { BackInserter =
>>>>> Element.second; });
>>>>> +  std::vector<int> ExpectedEvens = {2, 4, 6};
>>>>> +  EXPECT_EQ(Evens, ExpectedEvens);
>>>>> +}
>>>>> +
>>>>>  }
>>>>> Index: include/llvm/ADT/STLExtras.h
>>>>> ===================================================================
>>>>> --- include/llvm/ADT/STLExtras.h
>>>>> +++ include/llvm/ADT/STLExtras.h
>>>>> @@ -852,6 +852,13 @@
>>>>>    return std::find_if_not(std::begin(Range), std::end(Range), P);
>>>>>  }
>>>>>
>>>>> +/// Provide wrapper to std::for_each which take ranges instead of
>>>>> having to
>>>>> +/// pass begin/end explicitly.
>>>>> +template <typename R, typename UnaryFunction>
>>>>> +UnaryFunction for_each(R &&Range, UnaryFunction F) {
>>>>> +  return std::for_each(std::begin(Range), std::end(Range), F);
>>>>> +}
>>>>> +
>>>>>  /// Provide wrappers to std::remove_if which take ranges instead of
>>>>> having to
>>>>>  /// pass begin/end explicitly.
>>>>>  template <typename R, typename UnaryPredicate>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> llvm-commits mailing list
>>>>> llvm-commits at lists.llvm.org
>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>>>>>
>>>>
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