conversion from/to user-defined types #435

nlohmann · 2017-01-24T14:22:39Z

This PR is #423 after a small cleanup. Nothing substantial has changed - mostly documentation was touched.

the first is the basic_json type, the second the user-defined type

…ew methods

theodelrieu

I added a few comments (mainly those you added to the previous PR)

theodelrieu · 2017-01-24T14:44:02Z

src/json.hpp.re2c

-// I'm sure there is a better way, but this might need a big basic_json refactoring
-template <value_t> struct external_constructor;
+// I'm sure there is a better way, but this might need a big basic_json
+// refactoring


I think we can remove a part of this comment, we could only keep the part about the 'there might be a better way'

I removed the comment altogether.

theodelrieu · 2017-01-24T14:45:01Z

README.md

 ```

-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... Hopefully, there's a better way:


I think you talked about replacing 'Hopefully' with 'Fortunately'

I forgot about that, thanks!

theodelrieu · 2017-01-24T14:46:41Z

README.md

 } // namespace ns
 ```

-That's all. When calling the json constructor with your type, your custom `to_json` method will be automatically called.
+That's all! When calling the `json` constructor with your type, your custom `to_json` method will be automatically called.
 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).


About that part, I don't know if we should add a part mentioning that it can work in the global namespace.
It might not be clear for everyone.

I think about how to formulate this briefly.

I added a small comment.

theodelrieu · 2017-01-24T14:48:19Z

README.md

 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 and CopyConstructible (There is a way to bypass those requirements described later)
+* 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.)


I removed the need for CopyConstructible. This way, some types can be used thanks to copy elision.
If you think this is not a really good idea, you could simply put that check back in the static_assert

I removed mention of CopyConstructible.

nlohmann · 2017-01-24T16:03:32Z

Thanks for the comments! I shall have a look later this week.

coveralls · 2017-01-25T01:45:48Z

Coverage remained the same at 100.0% when pulling 4139bb6 on theodelrieu-feature/fromtojson into ce0b3fe on develop.

jaredgrubb · 2017-01-25T08:26:41Z

README.md

+
+#### Basic usage
+
+To make this work with one of your types, you only need to provide two methods:


Maybe: "... two functions" instead of "... two methods". Method sounds like a class method, whereas here it really is two free-standing functions.

Good point!

theodelrieu · 2017-01-25T09:25:25Z

~~We could also add a sentence about enums. Right now, only enum class are serializable via from_json/to_json without specializing adl_serializer~~

EDIT: I'm wrong, all wrong, everything works

theodelrieu · 2017-01-25T11:00:20Z

doc/Doxyfile

@@ -109,7 +109,7 @@ RECURSIVE              = NO
 EXCLUDE                =
 EXCLUDE_SYMLINKS       = NO
 EXCLUDE_PATTERNS       =
-EXCLUDE_SYMBOLS        = nlohmann::anonymous_namespace
+EXCLUDE_SYMBOLS        = nlohmann::detail


Should we bump the version number here too?

I shall change the version number once I created a release branch.

nlohmann · 2017-01-25T18:02:27Z

@theodelrieu I would not know what to write about the enums - don't they work the same?

coveralls · 2017-01-25T23:11:20Z

Coverage remained the same at 100.0% when pulling ec03c9c on theodelrieu-feature/fromtojson into ce0b3fe on develop.

coveralls · 2017-01-26T03:32:47Z

Coverage remained the same at 100.0% when pulling 4d3053c on theodelrieu-feature/fromtojson into ce0b3fe on develop.

coveralls · 2017-01-26T06:08:41Z

Coverage remained the same at 100.0% when pulling 4d3053c on theodelrieu-feature/fromtojson into ce0b3fe on develop.

coveralls · 2017-01-26T08:30:36Z

Coverage remained the same at 100.0% when pulling 77bb7af on theodelrieu-feature/fromtojson into ce0b3fe on develop.

theodelrieu · 2017-01-26T09:01:37Z

Well, I thought they didn't, since I added this overload in detail:

template<typename BasicJsonType, typename UnscopedEnumType,
         enable_if_t<is_unscoped_enum<UnscopedEnumType>::value, int> = 0>
void to_json(BasicJsonType& j, UnscopedEnumType e) noexcept { /* ... */ }

However I tested it with the following code, and it does work:

enum test{};
void to_json(json& j, test t) {} // this method is called

I thought this would be an ambiguous call, but since the second one is a perfect match, it isn't!

So, nevermind what I said, no need to add it in the doc!

theodelrieu · 2017-01-26T10:05:44Z

README.md

+        // will not be able to convert move_only_type to json, since you fully
+        // specialized adl_serializer on that type
+        static void to_json(json& j, move_only_type t) {
+            j = t.i;


t.i is private here

Right... Did I change this?

I don't know, but just removing private: is fine for this example

theodelrieu · 2017-01-26T10:06:56Z

README.md

+Some important things:
+
+* 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.)


Maybe rephrase the sentence in parenthesis : (There is a way to bypass this requirement described later).

coveralls · 2017-01-26T23:19:17Z

Coverage remained the same at 100.0% when pulling cd9701b on theodelrieu-feature/fromtojson into ce0b3fe on develop.

coveralls · 2017-01-27T03:35:55Z

Coverage remained the same at 100.0% when pulling cd9701b on theodelrieu-feature/fromtojson into ce0b3fe on develop.

nlohmann · 2017-01-27T05:23:08Z

Thanks for the feedback, @jaredgrubb !

And thanks for the awesome implementation @theodelrieu !

Théo Delrieu and others added 30 commits January 21, 2017 16:14

add first version support for user-defined types

b443edf

anonymous namespace renamed to detail

fe628b5

add alias templates to reduce boilerplate

d54d6bb

rename __static_const to _static_const (reserved identifier)

877d96c

use uncvref_t<T> instead of remove_cv_t<remove_reference_t<T>>>

12b4555

remove has_destructor and has_json_traits, use decltype instead

03b391c

move most SFINAE trickery in to/from_json_fn

4cdc61e

add first version for alternate implementation

7dc268e

add template arguments for JSONSerializer

33abccf

renamed unit-constructor3.cpp to unit-udt.cpp

837b81d

to_json and from_json takes both two arguments now

2bc685f

the first is the basic_json type, the second the user-defined type

add basic test for custom serializer

178441c

add is_compatible_* traits

23bd2bc

remove constraints on JSONSerializer instances, constrain correctly n…

8881944

…ew methods

add negation, disjunction, and conjunction from C++17

0d91113

correctly constrain basic_json udt constructor

e2dbe7a

add a macro for has_xxx types

9b40197

add is_compatible_basic_json_type trait

ee19aca

only use conjunction & co when needed to avoid MSVC crashing

47bc402

format biggest lines

907484f

remove some useless checks, format a bit, added some comments

74bb11d

add a few tests

e5999c6

add support for non-default-constructible udt

60e6f82

rewrite unit-udt: basic usage

c0c72b5

remove explicit keyword on udt-constructor

1eafac7

add an enum constructor (quickfix)

f5cb089

add more tests to unit-udt.cpp

8e43d47

add support for enum classes

3d405c6

fix msvc, by doubling parenthesis on catch assertions

7e750ec

use u8 prefix in unit-udt.cpp

1c21c87

📝 adjusted test count

4139bb6

nlohmann added the kind: enhancement/improvement label Jan 24, 2017

nlohmann added this to the Release 2.1.0 milestone Jan 24, 2017

nlohmann self-assigned this Jan 24, 2017

nlohmann mentioned this pull request Jan 24, 2017

user-defined types ter: clean, refactor basic_json class #423

Closed

theodelrieu reviewed Jan 24, 2017

View reviewed changes

jaredgrubb reviewed Jan 25, 2017

View reviewed changes

theodelrieu reviewed Jan 25, 2017

View reviewed changes

📝 overworked docs #435

ec03c9c

nlohmann added 2 commits January 25, 2017 21:59

📝 overworked documentation (re-added constructor examples)

94d9b7b

💄 some cleanup

4d3053c

📝 added more documentation

77bb7af

theodelrieu reviewed Jan 26, 2017

View reviewed changes

nlohmann added 2 commits January 26, 2017 19:39

📝 fixed documentation

1305e03

💄 cleanup

cd9701b

nlohmann merged commit 42fa3f0 into develop Jan 27, 2017

nlohmann deleted the theodelrieu-feature/fromtojson branch January 27, 2017 05:22

nlohmann mentioned this pull request Jan 27, 2017

Add a customization point for user-defined types #328

Closed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

conversion from/to user-defined types #435

conversion from/to user-defined types #435

nlohmann commented Jan 24, 2017

theodelrieu left a comment

theodelrieu Jan 24, 2017

nlohmann Jan 25, 2017

nlohmann Jan 25, 2017

theodelrieu Jan 24, 2017

nlohmann Jan 25, 2017

nlohmann Jan 25, 2017

theodelrieu Jan 24, 2017

nlohmann Jan 25, 2017

nlohmann Jan 25, 2017

theodelrieu Jan 24, 2017

nlohmann Jan 25, 2017

nlohmann commented Jan 24, 2017

coveralls commented Jan 25, 2017

jaredgrubb Jan 25, 2017

nlohmann Jan 25, 2017

theodelrieu commented Jan 25, 2017 •

edited

theodelrieu Jan 25, 2017

nlohmann Jan 25, 2017

nlohmann commented Jan 25, 2017

coveralls commented Jan 25, 2017

coveralls commented Jan 26, 2017

coveralls commented Jan 26, 2017

coveralls commented Jan 26, 2017

theodelrieu commented Jan 26, 2017

theodelrieu Jan 26, 2017

nlohmann Jan 26, 2017

theodelrieu Jan 26, 2017

theodelrieu Jan 26, 2017

coveralls commented Jan 26, 2017

coveralls commented Jan 27, 2017

nlohmann commented Jan 27, 2017


		#### Basic usage

		To make this work with one of your types, you only need to provide two methods:

conversion from/to user-defined types #435

conversion from/to user-defined types #435

Conversation

nlohmann commented Jan 24, 2017

theodelrieu left a comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

nlohmann commented Jan 24, 2017

coveralls commented Jan 25, 2017

Choose a reason for hiding this comment

Choose a reason for hiding this comment

theodelrieu commented Jan 25, 2017 • edited

Choose a reason for hiding this comment

Choose a reason for hiding this comment

nlohmann commented Jan 25, 2017

coveralls commented Jan 25, 2017

coveralls commented Jan 26, 2017

coveralls commented Jan 26, 2017

coveralls commented Jan 26, 2017

theodelrieu commented Jan 26, 2017

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

coveralls commented Jan 26, 2017

coveralls commented Jan 27, 2017

nlohmann commented Jan 27, 2017

theodelrieu commented Jan 25, 2017 •

edited