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📝 overworked docs #435

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Niels Lohmann 2017-01-25 19:01:31 +01:00
parent 4139bb6572
commit ec03c9c53e
3 changed files with 7 additions and 14 deletions
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15
README.md
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@ -475,7 +475,7 @@ ns::person p {
};
```
It works, but that's quite a lot of boilerplate... Hopefully, there's a better way:
It works, but that's quite a lot of boilerplate... Fortunately, there's a better way:
```cpp
// create a person
@ -496,17 +496,17 @@ assert(p == p2);
#### Basic usage
To make this work with one of your types, you only need to provide two methods:
To make this work with one of your types, you only need to provide two functions:
```cpp
using nlohmann::json;
namespace ns {
void to_json(json& j, person const& p) {
void to_json(json& j, const person& p) {
j = json{{"name", p.name}, {"address", p.address}, {"age", p.age}};
}
void from_json(json const& j, person& p) {
void from_json(const json& j, person& p) {
p.name = j["name"].get<std::string>();
p.address = j["address"].get<std::string>();
p.age = j["age"].get<int>();
@ -519,13 +519,12 @@ Likewise, when calling `get<your_type>()`, the `from_json` method will be called
Some important things:
* Those methods **MUST** be in your type's namespace, or the library will not be able to locate them (in this example, they are in namespace `ns`, where `person` is defined).
* When using `get<your_type>()`, `your_type` **MUST** be [DefaultConstructible](http://en.cppreference.com/w/cpp/concept/DefaultConstructible) and [CopyConstructible](http://en.cppreference.com/w/cpp/concept/CopyConstructible). (There is a way to bypass those requirements described later.)
* Those methods **MUST** be in your type's namespace (which can be the global namespace), or the library will not be able to locate them (in this example, they are in namespace `ns`, where `person` is defined).
* When using `get<your_type>()`, `your_type` **MUST** be [DefaultConstructible](http://en.cppreference.com/w/cpp/concept/DefaultConstructible). (There is a way to bypass those requirements described later.)
#### How do I convert third-party types?
This requires a bit more advanced technique.
But first, let's see how this conversion mechanism works:
This requires a bit more advanced technique. But first, let's see how this conversion mechanism works:
The library uses **JSON Serializers** to convert types to json.
The default serializer for `nlohmann::json` is `nlohmann::adl_serializer` (ADL means [Argument-Dependent Lookup](http://en.cppreference.com/w/cpp/language/adl)).

3
src/json.hpp
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@ -239,9 +239,6 @@ template<> struct priority_tag<0> {};
// constructors //
//////////////////
// This is an experiment. I need this to move constructors out of basic_json.
// I'm sure there is a better way, but this might need a big basic_json
// refactoring
template<value_t> struct external_constructor;
template<>

3
src/json.hpp.re2c
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@ -239,9 +239,6 @@ template<> struct priority_tag<0> {};
// constructors //
//////////////////
// This is an experiment. I need this to move constructors out of basic_json.
// I'm sure there is a better way, but this might need a big basic_json
// refactoring
template<value_t> struct external_constructor;
template<>