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add spaces in requires expressions (#2098)

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Eisenwave
2023-06-24 05:38:55 +02:00
committed by GitHub
parent a80c2a6f36
commit 95aca76777
1 changed files with 7 additions and 7 deletions
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CppCoreGuidelines.md
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@@ -17519,7 +17519,7 @@ and should be used only as building blocks for meaningful concepts, rather than
template<typename T>
// bad; insufficient
concept Addable = requires(T a, T b) { a+b; };
concept Addable = requires(T a, T b) { a + b; };
template<Addable N>
auto algo(const N& a, const N& b) // use two numbers
@@ -17547,7 +17547,7 @@ The ability to specify meaningful semantics is a defining characteristic of a tr
template<typename T>
// The operators +, -, *, and / for a number are assumed to follow the usual mathematical rules
concept Number = requires(T a, T b) { a+b; a-b; a*b; a/b; };
concept Number = requires(T a, T b) { a + b; a - b; a * b; a / b; };
template<Number N>
auto algo(const N& a, const N& b)
@@ -17588,7 +17588,7 @@ This is a specific variant of the general rule that [a concept must make semanti
##### Example, bad
template<typename T> concept Subtractable = requires(T a, T b) { a-b; };
template<typename T> concept Subtractable = requires(T a, T b) { a - b; };
This makes no semantic sense.
You need at least `+` to make `-` meaningful and useful.
@@ -17678,10 +17678,10 @@ Specifying semantics is a powerful design tool.
// The operators +, -, *, and / for a number are assumed to follow the usual mathematical rules
// axiom(T a, T b) { a + b == b + a; a - a == 0; a * (b + c) == a * b + a * c; /*...*/ }
concept Number = requires(T a, T b) {
{a + b} -> convertible_to<T>;
{a - b} -> convertible_to<T>;
{a * b} -> convertible_to<T>;
{a / b} -> convertible_to<T>;
{ a + b } -> convertible_to<T>;
{ a - b } -> convertible_to<T>;
{ a * b } -> convertible_to<T>;
{ a / b } -> convertible_to<T>;
};
##### Note