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PR-URL: https://github.com/nodejs/node/pull/16548 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com> Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com> Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
154 lines
3.4 KiB
Markdown
154 lines
3.4 KiB
Markdown
# C++ Style Guide
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Unfortunately, the C++ linter (based on
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[Google’s `cpplint`](https://github.com/google/styleguide)), which can be run
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explicitly via `make lint-cpp`, does not currently catch a lot of rules that are
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specific to the Node.js C++ code base. This document explains the most common of
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these rules:
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## Left-leaning (C++ style) asterisks for pointer declarations
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`char* buffer;` instead of `char *buffer;`
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## 2 spaces of indentation for blocks or bodies of conditionals
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```c++
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if (foo)
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bar();
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```
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or
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```c++
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if (foo) {
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bar();
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baz();
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}
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```
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Braces are optional if the statement body only has one line.
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`namespace`s receive no indentation on their own.
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## 4 spaces of indentation for statement continuations
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```c++
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VeryLongTypeName very_long_result = SomeValueWithAVeryLongName +
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SomeOtherValueWithAVeryLongName;
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```
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Operators are before the line break in these cases.
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## Align function arguments vertically
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```c++
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void FunctionWithAVeryLongName(int parameter_with_a_very_long_name,
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double other_parameter_with_a_very_long_name,
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...);
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```
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If that doesn’t work, break after the `(` and use 4 spaces of indentation:
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```c++
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void FunctionWithAReallyReallyReallyLongNameSeriouslyStopIt(
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int okay_there_is_no_space_left_in_the_previous_line,
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...);
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```
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## Initialization lists
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Long initialization lists are formatted like this:
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```c++
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HandleWrap::HandleWrap(Environment* env,
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Local<Object> object,
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uv_handle_t* handle,
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AsyncWrap::ProviderType provider)
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: AsyncWrap(env, object, provider),
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state_(kInitialized),
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handle_(handle) {
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```
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## CamelCase for methods, functions and classes
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Exceptions are simple getters/setters, which are named `property_name()` and
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`set_property_name()`, respectively.
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```c++
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class FooBar {
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public:
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void DoSomething();
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static void DoSomethingButItsStaticInstead();
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void set_foo_flag(int flag_value);
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int foo_flag() const; // Use const-correctness whenever possible.
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};
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```
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## snake\_case for local variables and parameters
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```c++
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int FunctionThatDoesSomething(const char* important_string) {
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const char* pointer_into_string = important_string;
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}
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```
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## snake\_case\_ for private class fields
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```c++
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class Foo {
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private:
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int counter_ = 0;
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};
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```
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## Space after `template`
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```c++
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template <typename T>
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class FancyContainer {
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...
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}
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```
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## Type casting
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- Always avoid C-style casts (`(type)value`)
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- `dynamic_cast` does not work because RTTI is not enabled
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- Use `static_cast` for casting whenever it works
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- `reinterpret_cast` is okay if `static_cast` is not appropriate
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## Memory allocation
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- `Malloc()`, `Calloc()`, etc. from `util.h` abort in Out-of-Memory situations
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- `UncheckedMalloc()`, etc. return `nullptr` in OOM situations
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## `nullptr` instead of `NULL` or `0`
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What it says in the title.
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## Do not include `*.h` if `*-inl.h` has already been included
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Do
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```cpp
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#include "util-inl.h" // already includes util.h
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```
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instead of
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```cpp
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#include "util.h"
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#include "util-inl.h"
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```
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## Avoid throwing JavaScript errors in nested C++ methods
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If you need to throw JavaScript errors from a C++ binding method, try to do it
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at the top level and not inside of nested calls.
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A lot of code inside Node.js is written so that typechecking etc. is performed
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in JavaScript.
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Using C++ `throw` is not allowed.
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