The Guidelines Support Library (GSL) contains functions and types that are suggested for use by the C++ Core Guidelines maintained by the Standard C++ Foundation.
Questions tagged [guideline-support-library]
41 questions
103
votes
3 answers
What's the difference between span and array_view in the gsl library?
In several recent conference presentation I've heard Bjarne Stroustrup and others mention new coding guidelines for C++ and some types supporting them.
Specifically, I remember the example of span instead of (T* p, int n) as a parameter to a…
einpoklum
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76
votes
2 answers
gsl::not_null vs. std::reference_wrapper vs. T&
C++ Core Guidelines has been presented recently (congrats!) and I am concerned about gsl::not_null type. As stated in I.12: Declare a pointer that must not be null as not_null:
To help avoid dereferencing nullptr errors. To improve performance by
…
Mikhail
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29
votes
2 answers
What are the C++ GSL guidelines?
Stroustrup gave a talk last year about his GSL (Guideline Support Library). There is an implementation by Micosoft at https://github.com/Microsoft/GSL . I was under the impression that the GSL was supposed to advise on bad coding style, and suggest…
blippy
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10
votes
1 answer
Advantage of gsl assert vs assert in c++?
I know the use of assert in C++. Wanted to know is there any difference between and any benefit(I think assert is costlier according as mentioned in https://www.learncpp.com/cpp-tutorial/7-12a-assert-and-static_assert/ so performance wise, are both…
suresh m
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8
votes
1 answer
Ensures() - guideline support library
I am trying to understand how to use Ensures() in code. As given in the example, if I tried using Ensures() as follows...
int main(void)
{
int result = 0;
// Some calculation
Ensures(result == 255);
return 0;
}
If the result…
NJMR
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7
votes
2 answers
What does narrow_cast do?
I saw a code that used narrow_cast like this
int num = narrow_cast(26.72);
cout << num;
The problem is my compiler said:
'narrow_cast' was not decleared in this scope.
Am I supposed to define narrow_cast myself or am I using it the wrong…
Lekan
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7
votes
1 answer
Understanding the need for this `const&` specialization
In the Guidelines Support Library there is a class called final_action (essentially the well known ScopeGuard). There are 2 free-standing convenience functions to generate this templated class:
// finally() - convenience function to generate a…
Baruch
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7
votes
0 answers
Avoiding loss of __restrict__ when using GSL spans
I (mostly) like the new C++ Core Guidelines initiative, and what the Guidelines Support Libary offers. Specifically, I want to use spans more. However, I'm coming up against the issue of __restrict__ not being part of C++ while I want to/need to…
einpoklum
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7
votes
1 answer
Using gsl::span with range-v3
I tried a little example to get used to the GSL and range-v3 libraries and I wondered how they could work together. I have this toy example
#include
#include
using namespace std;
using namespace ranges;
void…
Maikel
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6
votes
1 answer
Difference between std::basic_string_view and std::span
I'm parsing a binary network data and i would like to make the process as allocation-less as possible. But now i realized there are 2 very similar concepts that are probably both good enough for my case, and those are std::basic_string_view and…
Youda008
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6
votes
1 answer
How do gsl::string_span and std::string_view differ?
From what I can gather, gsl::string_span and std::string_view seem to have essentially the same rationale for use. Is that indeed the case? If so, are they effectively identical? If not - how do they differ?
Related question: What purpose does…
einpoklum
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6
votes
2 answers
Should I return gsl::span instead of const std::vector&
I have a class with a std::vector member and a member function returning a const reference to that vector.
class demo {
public:
//...
const std::vector & test() const {
return iv;
}
private:
std::vector…
Stefan F.
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5
votes
0 answers
How to properly install a header that includes GSL (Guidelines Support Library)
// include/MyLib/MyModel.h
#include
#include
#include "myEntity.h"
#include
class MyModel {
public:
std::unique_ptr load(std::string id);
bool store(gsl::not_null entity); //…
Oleg
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5
votes
1 answer
How can I use gsl::span and indicate ownership?
I want to write a function which:
Takes a pointer as a parameter
Takes a length as a parameter
Owns the memory pointed to by the pointer (e.g. maybe it releases it, or constructs a unique_ptr to it in some data structure etc.)
Now, if I wanted 1+2…
einpoklum
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5
votes
3 answers
Should I replace (void*, size) with a GSL span?
Suppose I have
int foo(void* p, size_t size_in_bytes);
and assume it doesn't make sense to make foo typed. I want to be a good coder and apply the C++ core guidelines. Specifically, I want to use spans instead of (*, len) pairs. Well, span…
einpoklum
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