doc: cleanup and add references to CPP_STYLE_GUIDE.md #23650

refack · 2018-10-14T01:07:09Z

Checklist

make -j4 test (UNIX), or vcbuild test (Windows) passes
documentation is changed or added
commit message follows commit guidelines

nodejs-github-bot · 2018-10-14T01:07:10Z

@refack build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/1239/pipeline

richardlau · 2018-10-14T01:21:16Z

CPP_STYLE_GUIDE.md

 not inside of nested calls.

-Using C++ `throw` is not allowed.
+Node.js is built without C++ exception semantics, so code using `thorw` or, even


thorw->throw

richardlau · 2018-10-14T01:21:59Z

CPP_STYLE_GUIDE.md

 ```cpp
 std::unique_ptr<Foo> FooFactory();
 void FooConsumer(std::unique_ptr<Foo> ptr);
 ```
+Since `std::unique_ptr` has only move semantics, passing one by value trasfers


trasfers->transfers

addaleax · 2018-10-14T03:03:24Z

CPP_STYLE_GUIDE.md

@@ -316,13 +311,19 @@ exports.foo = function(str) {

 #### Avoid throwing JavaScript errors in nested C++ methods

-When you have to throw the errors from C++, try to do it at the top level and
+When you need to return an error from C++, try to do it at the top level and


This referred specifically to throwing exceptions, though.

(s/error/exception/ would be a good change here, that’s on me.)

Can you clear this up for me? we can't c++ throw, we need to isolate()->ThrowException() right?

addaleax · 2018-10-14T03:04:00Z

CPP_STYLE_GUIDE.md

- Use `static_cast` for casting whenever it works
- `reinterpret_cast` is okay if `static_cast` is not appropriate
+- Use `static_cast<T>` if casting is required, and its valid 
+- Use `reinterpret_cast` only when its essential


typo: it is (twice)

(and maybe s/essential/necessary/)

addaleax · 2018-10-14T03:05:04Z

CPP_STYLE_GUIDE.md


-Never use `std::auto_ptr`. Instead, use `std::unique_ptr`.
+Avoid `std::auto_ptr`. It was deprecated in C++11 and removed from C++17.


This seemed sensible in previous form? There’s no reason to use it in our code, and that it’s deprecated/removed is not really of concern if you already know not to use it

I didn't like the phrasing "Never use", also I do believe an explanation why is nice, since it's very short.

Maybe:

Don't use `std::auto_ptr`.<br/> It was deprecated in C++11 if favor of `std::unique_ptr`, and later removed from C++17. `std::unique_ptr` has move semantics instead the of unusual copy semantics of `std::auto_ptr`.

Actually we should be able to lint for that. I'll see if I can figure out how to.

addaleax · 2018-10-14T03:05:49Z

CPP_STYLE_GUIDE.md

 ```cpp
 std::unique_ptr<Foo> FooFactory();
 void FooConsumer(std::unique_ptr<Foo> ptr);
 ```
+Since `std::unique_ptr` has only move semantics, passing one by value trasfers


nit: blank lines around code block

addaleax · 2018-10-14T03:07:27Z

CPP_STYLE_GUIDE.md

@@ -192,40 +192,35 @@ class FancyContainer {

 ### Use `nullptr` instead of `NULL` or `0`

-What it says in the title.
+Further reading at [ES.47].


I’d really like it if we could make these links more expressive instead of just having the item numbers in the text, e.g. Further reading in the [C++ Core Guidelines][ES.47]?

vsemozhetbyt · 2018-10-14T10:04:10Z

CPP_STYLE_GUIDE.md

-
-Prefer to use `std::unique_ptr` to make ownership
-transfer explicit. For example:
+[R.20]: Use `std::unique_ptr` or `std::shared_ptr` to represent ownership


Currently, this and next lines are rendered as one line.

CPP_STYLE_GUIDE.md

addaleax · 2018-10-14T19:41:17Z

CPP_STYLE_GUIDE.md

-Prefer to use `std::unique_ptr` to make ownership
-transfer explicit. For example:
+[R.20]: Use `std::unique_ptr` or `std::shared_ptr` to represent ownership<br/>
+[R.21]: Prefer `unique_ptr` over `shared_ptr` unless you need to share ownership


If you want a list of things, you can juse start lines with * instead of manually inserting line breaks

addaleax · 2018-10-14T19:41:32Z

CPP_STYLE_GUIDE.md

+Since `std::unique_ptr` has only move semantics, passing one by value transfers
+ownership to the callee and invalidates the instance the caller hold.
+
+Don't use `std::auto_ptr`.<br/>


No need for a line break, this makes sense as one paragraph.

addaleax · 2018-10-14T19:41:50Z

CPP_STYLE_GUIDE.md

+
+Further reading:<br/>
+[ES.48]: Avoid casts<br/>
+[ES.49]: If you must use a cast, use a named cast


refack · 2018-10-14T22:46:45Z

New format:

Explicit <br/> format:

🤔

addaleax

Thanks!

joyeecheung · 2018-10-14T22:53:16Z

CPP_STYLE_GUIDE.md

@@ -316,13 +316,19 @@ exports.foo = function(str) {

 #### Avoid throwing JavaScript errors in nested C++ methods

-When you have to throw the errors from C++, try to do it at the top level and
+When you need to throw an exception from C++, try to do it at the top level and


This somehow reads a bit ambiguous to me now that it's exception, can you change it to JavaScript exception?

joyeecheung · 2018-10-14T23:00:45Z

CPP_STYLE_GUIDE.md

+Since `std::unique_ptr` has only move semantics, passing one by value transfers
+ownership to the callee and invalidates the instance the caller hold.
+
+Don't use `std::auto_ptr`. It was deprecated in C++11 if favor of


Do we need to explain this here? Can we link to some docs somewhere?

Ack (ish). PTAL

refack · 2018-10-15T00:45:35Z

CPP_STYLE_GUIDE.md

+When you need to throw a JavaScript exception from C++ (i.e.
+`isolate()->ThrowException()`) prefer to do it as close to the return to JS as
+possible, and not inside of nested C++ calls. Since this changes the `isolate`'s
+state doing closest to where it is consumed, reduces the chance of side effects.


@joyeecheung, @addaleax PTAL
I'm trying to grok this, so I wrote it down.

s/isolate/Isolate/, and the comma should be removed

I don’t think it matters that it’s an Isolate thing, though. That’s implementation details, and you can just say “JS execution state” or something like that.

addaleax · 2018-10-15T00:47:35Z

CPP_STYLE_GUIDE.md


-Using C++ `throw` is not allowed.
+Node.js is built without C++ exception semantics, so code using `throw` or, even


s/exception semantics/exceptions/?

I went with exception handling and added a reference (GCC state 7% runtime cost which I think is interesting).

addaleax · 2018-10-15T00:48:08Z

CPP_STYLE_GUIDE.md

+When you need to throw a JavaScript exception from C++ (i.e.
+`isolate()->ThrowException()`) prefer to do it as close to the return to JS as
+possible, and not inside of nested C++ calls. Since this changes the `isolate`'s
+state doing closest to where it is consumed, reduces the chance of side effects.


s/isolate/Isolate/, and the comma should be removed

I don’t think it matters that it’s an Isolate thing, though. That’s implementation details, and you can just say “JS execution state” or something like that.

refack · 2018-10-16T15:32:35Z

Lite CI: ~~https://ci.nodejs.org/job/node-test-pull-request-lite-pipeline/1262/~~
https://ci.nodejs.org/job/node-test-pull-request-lite-pipeline/1268/

PR-URL: nodejs#23650 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

PR-URL: #23650 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

nodejs-github-bot added the doc Issues and PRs related to the documentations. label Oct 14, 2018

refack requested review from addaleax and joyeecheung October 14, 2018 01:07

refack self-assigned this Oct 14, 2018

refack added the c++ Issues and PRs that require attention from people who are familiar with C++. label Oct 14, 2018

richardlau reviewed Oct 14, 2018

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refack commented Oct 15, 2018

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refack force-pushed the more-references-in-cpp-guide branch from 41872c5 to 5764fdb Compare October 16, 2018 15:32

refack added the meta Issues and PRs related to the general management of the project. label Oct 16, 2018

doc: cleanup and references in C++ guide

cf3f8dd

PR-URL: nodejs#23650 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

refack force-pushed the more-references-in-cpp-guide branch from 5764fdb to cf3f8dd Compare October 16, 2018 21:50

refack merged commit cf3f8dd into nodejs:master Oct 16, 2018

refack deleted the more-references-in-cpp-guide branch October 16, 2018 22:05

jasnell pushed a commit that referenced this pull request Oct 17, 2018

doc: cleanup and references in C++ guide

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PR-URL: #23650 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

addaleax pushed a commit that referenced this pull request Oct 20, 2018

doc: cleanup and references in C++ guide

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PR-URL: #23650 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

refack removed their assignment Oct 20, 2018

MylesBorins pushed a commit that referenced this pull request Oct 30, 2018

doc: cleanup and references in C++ guide

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PR-URL: #23650 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

codebytere mentioned this pull request Nov 27, 2018

v10.13.1 proposal #24675

Closed

rvagg pushed a commit that referenced this pull request Nov 28, 2018

doc: cleanup and references in C++ guide

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PR-URL: #23650 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

MylesBorins pushed a commit that referenced this pull request Nov 29, 2018

doc: cleanup and references in C++ guide

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PR-URL: #23650 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

codebytere mentioned this pull request Nov 29, 2018

v10.14.2 proposal #24727

Merged


		Never use `std::auto_ptr`. Instead, use `std::unique_ptr`.
		Avoid `std::auto_ptr`. It was deprecated in C++11 and removed from C++17.


		Using C++ `throw` is not allowed.
		Node.js is built without C++ exception semantics, so code using `throw` or, even

doc: cleanup and add references to CPP_STYLE_GUIDE.md #23650

doc: cleanup and add references to CPP_STYLE_GUIDE.md #23650

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refack commented Oct 14, 2018

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