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I would prefer a more general, systematic approach to this situation.
I really don't want to be deal with adding `string` and `const char []`
overloads everywhere. Ideally, we'd have a `string_view` class that we
could use instead of `string` here.
Now, as far as performance goes, there are a couple of things to note.
(1) It seems like the claim is that it speeds up the tests? by how much?
(2) The claim that we avoid an unnecessary allocation isn't actually
true considering that the strings (at least in our tests) probably
fit within the short-string optimization.
(3) Is this change by itself a big win somewhere? or will it require
a systematic change where `string` can be a `string_view`?
If the former, I'd be fine with optimizing these functions, but
if it's the former, I'd say we should invest in a `string_view` class.
I quite like performance, but some more evidence would be helpful here.
Now, under the assumption that the performance argument to be justified,
we can simply make the existing function a template and generalize the logic:
```cpp
template <typename Stringish>
bool startsWith(const string& s, const Stringish& prefix) {
return s.size() >= distance(begin(prefix), end(prefix)) &&
equal(begin(prefix), end(prefix), begin(s));
}
```
- Michael Park
On Jan. 24, 2018, 7:12 a.m., Benno Evers wrote:
>
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> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/63367/
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>
> (Updated Jan. 24, 2018, 7:12 a.m.)
>
>
> Review request for mesos, Alexander Rukletsov and Benjamin Mahler.
>
>
> Repository: mesos
>
>
> Description
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>
> This saves an unnecessary memory allocation when
> testing if a string starts or ends with a string literal,
> which accounts for almost all usages of these functions
> in Mesos and in libprocess.
>
>
> Diffs
> -----
>
> 3rdparty/stout/include/stout/strings.hpp
> 067a7923c02342bccd9be1136a981fd6b0e0e9b4
> 3rdparty/stout/tests/strings_tests.cpp
> 395540aad88c76a66a43a54edfe9ca1a2d46d3b4
>
>
> Diff: https://reviews.apache.org/r/63367/diff/3/
>
>
> Testing
> -------
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>
> Thanks,
>
> Benno Evers
>
>
