> On Aug. 30, 2017, 5:14 p.m., Michael Park wrote:
> > 3rdparty/libprocess/include/process/future.hpp
> > Lines 1702-1703 (patched)
> > <https://reviews.apache.org/r/61987/diff/1/?file=1807590#file1807590line1702>
> >
> > Let's stick to the `typename std::enable_if<condition, int>::type = 0`
> > pattern for now.
>
> Benjamin Hindman wrote:
> How come? That's not what I've used other places ... what are the pros
> and cons of each approach?
The current approach doesn't allow you to SFINAE over an overload set.
For example,
```cpp
template <typename T, typename = typename
std::enable_if<std::is_integral<T>::value>::type>
void f(T) { std::cout << "integral\n"; }
template <typename T, typename = typename
std::enable_if<!std::is_integral<T>::value>::type>
void f(T) { std::cout << "!integral\n"; }
f(42); // doesn't work -- "redefining a default template parameter"
```
vs
```cpp
template <typename T, typename std::enable_if<std::is_integral<T>::value,
int>::type = 0>
void f(T) { std::cout << "integral\n"; }
template <typename T, typename std::enable_if<!std::is_integral<T>::value,
int>::type = 0>
void f(T) { std::cout << "!integral\n"; }
f(42); // works
```
In other cases it doesn't make a difference, so I prefer to just use this
pattern rather than trying to identify / teach cases where this is necessary.
- Michael
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-----------------------------------------------------------
On Aug. 30, 2017, 9:42 p.m., Benjamin Hindman wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/61987/
> -----------------------------------------------------------
>
> (Updated Aug. 30, 2017, 9:42 p.m.)
>
>
> Review request for mesos, Benjamin Mahler, Gilbert Song, and Jie Yu.
>
>
> Bugs: MESOS-7926
> https://issues.apache.org/jira/browse/MESOS-7926
>
>
> Repository: mesos
>
>
> Description
> -------
>
> This can be useful in circumstances where you don't want some
> asynchronous operation to be canceled.
>
>
> Diffs
> -----
>
> 3rdparty/libprocess/include/process/future.hpp
> 2f5f0a20b5a39b04fd684b1cb44b6a33b647bbef
> 3rdparty/libprocess/src/tests/future_tests.cpp
> 0c8725b9a5e64aaac6e3979e450a11e84f9bd45e
>
>
> Diff: https://reviews.apache.org/r/61987/diff/2/
>
>
> Testing
> -------
>
> make check
>
>
> Thanks,
>
> Benjamin Hindman
>
>
