This commit is contained in:
Bjarne Stroustrup
2017-04-02 20:42:52 -04:00
parent cbb3de625e
commit fbeff91d05

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@@ -2899,22 +2899,22 @@ However, we prefer to be explicit, rather than subtle.
##### Note
In many cases, it may be useful to return a specific, user-defined "Value or error" type.
In many cases, it may be useful to return a specific, user-defined type.
For example:
struct Distance {
int value;
int unit = 1; // 1 mens meters
int unit = 1; // 1 means meters
};
Distance d1 = measure(obj1); // access d1.value and d1.unit
auto d2 = measure(obj2); // access d2.value and d2.unit
auto [value, unit] = measure(obj3); // access value and unit; somewhat redundant to people who know measure()
auto [x,y] = measure(obj4); // don't; it's likely to be confusiong
auto [x,y] = measure(obj4); // don't; it's likely to be confusing
The overly-generic `pair` and `tuple` should be used only when the value returned represents to independent entities rather than an abstraction.
type along the lines of `variant<T, error_code>`, rather than using the generic `tuple`.
Another example, use a specific type along the lines of `variant<T, error_code>`, rather than using the generic `tuple`.
##### Enforcement