particularly important for large-scale code bases that follow a library-based
design (like LLVM).
-This document intentionally does not prescribe fixed standards for religious
-issues such as brace placement and space usage. For issues like this, follow
-the golden rule:
+While this document may provide guidance for some mechanical formatting issues,
+whitespace, or other "microscopic details", these are not fixed standards.
+Always follow the golden rule:
.. _Golden Rule:
from the coding standards. In the case of ``libc++``, this is because the
naming and other conventions are dictated by the C++ standard. If you think
there is a specific good reason to deviate from the standards here, please bring
-it up on the LLVMdev mailing list.
+it up on the LLVM-dev mailing list.
There are some conventions that are not uniformly followed in the code base
(e.g. the naming convention). This is because they are relatively new, and a
change it in some other way. Just do the reformating as a separate commit from
the functionality change.
-The ultimate goal of these guidelines is the increase readability and
+The ultimate goal of these guidelines is to increase the readability and
maintainability of our common source base. If you have suggestions for topics to
be included, please mail them to `Chris <mailto:sabre@nondot.org>`_.
+Languages, Libraries, and Standards
+===================================
+
+Most source code in LLVM and other LLVM projects using these coding standards
+is C++ code. There are some places where C code is used either due to
+environment restrictions, historical restrictions, or due to third-party source
+code imported into the tree. Generally, our preference is for standards
+conforming, modern, and portable C++ code as the implementation language of
+choice.
+
+C++ Standard Versions
+---------------------
+
+LLVM, Clang, and LLD are currently written using C++11 conforming code,
+although we restrict ourselves to features which are available in the major
+toolchains supported as host compilers. The LLDB project is even more
+aggressive in the set of host compilers supported and thus uses still more
+features. Regardless of the supported features, code is expected to (when
+reasonable) be standard, portable, and modern C++11 code. We avoid unnecessary
+vendor-specific extensions, etc.
+
+C++ Standard Library
+--------------------
+
+Use the C++ standard library facilities whenever they are available for
+a particular task. LLVM and related projects emphasize and rely on the standard
+library facilities for as much as possible. Common support libraries providing
+functionality missing from the standard library for which there are standard
+interfaces or active work on adding standard interfaces will often be
+implemented in the LLVM namespace following the expected standard interface.
+
+There are some exceptions such as the standard I/O streams library which are
+avoided. Also, there is much more detailed information on these subjects in the
+:doc:`ProgrammersManual`.
+
+Supported C++11 Language and Library Features
+---------------------------------------------
+
+While LLVM, Clang, and LLD use C++11, not all features are available in all of
+the toolchains which we support. The set of features supported for use in LLVM
+is the intersection of those supported in MSVC 2013, GCC 4.7, and Clang 3.1.
+The ultimate definition of this set is what build bots with those respective
+toolchains accept. Don't argue with the build bots. However, we have some
+guidance below to help you know what to expect.
+
+Each toolchain provides a good reference for what it accepts:
+
+* Clang: http://clang.llvm.org/cxx_status.html
+* GCC: http://gcc.gnu.org/projects/cxx0x.html
+* MSVC: http://msdn.microsoft.com/en-us/library/hh567368.aspx
+
+In most cases, the MSVC list will be the dominating factor. Here is a summary
+of the features that are expected to work. Features not on this list are
+unlikely to be supported by our host compilers.
+
+* Rvalue references: N2118_
+
+ * But *not* Rvalue references for ``*this`` or member qualifiers (N2439_)
+
+* Static assert: N1720_
+* ``auto`` type deduction: N1984_, N1737_
+* Trailing return types: N2541_
+* Lambdas: N2927_
+
+ * But *not* lambdas with default arguments.
+
+* ``decltype``: N2343_
+* Nested closing right angle brackets: N1757_
+* Extern templates: N1987_
+* ``nullptr``: N2431_
+* Strongly-typed and forward declarable enums: N2347_, N2764_
+* Local and unnamed types as template arguments: N2657_
+* Range-based for-loop: N2930_
+
+ * But ``{}`` are required around inner ``do {} while()`` loops. As a result,
+ ``{}`` are required around function-like macros inside range-based for
+ loops.
+
+* ``override`` and ``final``: N2928_, N3206_, N3272_
+* Atomic operations and the C++11 memory model: N2429_
+* Variadic templates: N2242_
+* Explicit conversion operators: N2437_
+* Defaulted and deleted functions: N2346_
+
+ * But not defaulted move constructors or move assignment operators, MSVC 2013
+ cannot synthesize them.
+* Initializer lists: N2627_
+* Delegating constructors: N1986_
+* Default member initializers (non-static data member initializers): N2756_
+
+ * Only use these for scalar members that would otherwise be left
+ uninitialized. Non-scalar members generally have appropriate default
+ constructors, and MSVC 2013 has problems when braced initializer lists are
+ involved.
+
+.. _N2118: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2118.html
+.. _N2439: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2439.htm
+.. _N1720: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1720.html
+.. _N1984: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1984.pdf
+.. _N1737: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1737.pdf
+.. _N2541: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2541.htm
+.. _N2927: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2927.pdf
+.. _N2343: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2343.pdf
+.. _N1757: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1757.html
+.. _N1987: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1987.htm
+.. _N2431: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2431.pdf
+.. _N2347: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf
+.. _N2764: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2764.pdf
+.. _N2657: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2657.htm
+.. _N2930: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2930.html
+.. _N2928: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2928.htm
+.. _N3206: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3206.htm
+.. _N3272: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3272.htm
+.. _N2429: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2429.htm
+.. _N2242: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2242.pdf
+.. _N2437: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2437.pdf
+.. _N2346: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2346.htm
+.. _N2627: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2672.htm
+.. _N1986: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1986.pdf
+.. _N2756: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2756.htm
+
+The supported features in the C++11 standard libraries are less well tracked,
+but also much greater. Most of the standard libraries implement most of C++11's
+library. The most likely lowest common denominator is Linux support. For
+libc++, the support is just poorly tested and undocumented but expected to be
+largely complete. YMMV. For libstdc++, the support is documented in detail in
+`the libstdc++ manual`_. There are some very minor missing facilities that are
+unlikely to be common problems, and there are a few larger gaps that are worth
+being aware of:
+
+* Not all of the type traits are implemented
+* No regular expression library.
+* While most of the atomics library is well implemented, the fences are
+ missing. Fortunately, they are rarely needed.
+* The locale support is incomplete.
+* ``std::equal()`` (and other algorithms) incorrectly assert in MSVC when given
+ ``nullptr`` as an iterator.
+
+Other than these areas you should assume the standard library is available and
+working as expected until some build bot tells you otherwise. If you're in an
+uncertain area of one of the above points, but you cannot test on a Linux
+system, your best approach is to minimize your use of these features, and watch
+the Linux build bots to find out if your usage triggered a bug. For example, if
+you hit a type trait which doesn't work we can then add support to LLVM's
+traits header to emulate it.
+
+.. _the libstdc++ manual:
+ http://gcc.gnu.org/onlinedocs/gcc-4.7.3/libstdc++/manual/manual/status.html#status.iso.2011
+
+Other Languages
+---------------
+
+Any code written in the Go programming language is not subject to the
+formatting rules below. Instead, we adopt the formatting rules enforced by
+the `gofmt`_ tool.
+
+Go code should strive to be idiomatic. Two good sets of guidelines for what
+this means are `Effective Go`_ and `Go Code Review Comments`_.
+
+.. _gofmt:
+ https://golang.org/cmd/gofmt/
+
+.. _Effective Go:
+ https://golang.org/doc/effective_go.html
+
+.. _Go Code Review Comments:
+ https://code.google.com/p/go-wiki/wiki/CodeReviewComments
+
Mechanical Source Issues
========================
//===----------------------------------------------------------------------===//
///
/// \file
- /// \brief This file contains the declaration of the Instruction class, which is
- /// the base class for all of the VM instructions.
+ /// This file contains the declaration of the Instruction class, which is the
+ /// base class for all of the VM instructions.
///
//===----------------------------------------------------------------------===//
file is released under. This makes it perfectly clear what terms the source
code can be distributed under and should not be modified in any way.
-The main body is a ``doxygen`` comment describing the purpose of the file. It
-should have a ``\brief`` command that describes the file in one or two
-sentences. Any additional information should be separated by a blank line. If
-an algorithm is being implemented or something tricky is going on, a reference
+The main body is a ``doxygen`` comment (identified by the ``///`` comment
+marker instead of the usual ``//``) describing the purpose of the file. The
+first sentence or a passage beginning with ``\brief`` is used as an abstract.
+Any additional information should be separated by a blank line. If an
+algorithm is being implemented or something tricky is going on, a reference
to the paper where it is published should be included, as well as any notes or
*gotchas* in the code to watch out for.
Comment Formatting
^^^^^^^^^^^^^^^^^^
-In general, prefer C++ style (``//``) comments. They take less space, require
+In general, prefer C++ style comments (``//`` for normal comments, ``///`` for
+``doxygen`` documentation comments). They take less space, require
less typing, don't have nesting problems, etc. There are a few cases when it is
useful to use C style (``/* */``) comments however:
Use the ``\file`` command to turn the standard file header into a file-level
comment.
-Include descriptive ``\brief`` paragraphs for all public interfaces (public
-classes, member and non-member functions). Explain API use and purpose in
-``\brief`` paragraphs, don't just restate the information that can be inferred
-from the API name. Put detailed discussion into separate paragraphs.
+Include descriptive paragraphs for all public interfaces (public classes,
+member and non-member functions). Don't just restate the information that can
+be inferred from the API name. The first sentence or a paragraph beginning
+with ``\brief`` is used as an abstract. Put detailed discussion into separate
+paragraphs.
To refer to parameter names inside a paragraph, use the ``\p name`` command.
Don't use the ``\arg name`` command since it starts a new paragraph that
.. code-block:: c++
- /// \brief Does foo and bar.
- void fooBar(bool Baz);
+ /// Sets the xyzzy property to \p Baz.
+ void setXyzzy(bool Baz);
A documentation comment that uses all Doxygen features in a preferred way:
// In Something.h:
- /// \brief An abstraction for some complicated thing.
+ /// An abstraction for some complicated thing.
class Something {
public:
- /// \brief Does foo and bar.
+ /// Does foo and bar.
void fooBar();
};
^^^^^^^^^^^^^^^^^^^^^^^^
Okay, in your first year of programming you were told that indentation is
-important. If you didn't believe and internalize this then, now is the time.
-Just do it.
+important. If you didn't believe and internalize this then, now is the time.
+Just do it. With the introduction of C++11, there are some new formatting
+challenges that merit some suggestions to help have consistent, maintainable,
+and tool-friendly formatting and indentation.
-Compiler Issues
----------------
+Format Lambdas Like Blocks Of Code
+""""""""""""""""""""""""""""""""""
+
+When formatting a multi-line lambda, format it like a block of code, that's
+what it is. If there is only one multi-line lambda in a statement, and there
+are no expressions lexically after it in the statement, drop the indent to the
+standard two space indent for a block of code, as if it were an if-block opened
+by the preceding part of the statement:
+
+.. code-block:: c++
+
+ std::sort(foo.begin(), foo.end(), [&](Foo a, Foo b) -> bool {
+ if (a.blah < b.blah)
+ return true;
+ if (a.baz < b.baz)
+ return true;
+ return a.bam < b.bam;
+ });
+
+To take best advantage of this formatting, if you are designing an API which
+accepts a continuation or single callable argument (be it a functor, or
+a ``std::function``), it should be the last argument if at all possible.
+
+If there are multiple multi-line lambdas in a statement, or there is anything
+interesting after the lambda in the statement, indent the block two spaces from
+the indent of the ``[]``:
+
+.. code-block:: c++
+
+ dyn_switch(V->stripPointerCasts(),
+ [] (PHINode *PN) {
+ // process phis...
+ },
+ [] (SelectInst *SI) {
+ // process selects...
+ },
+ [] (LoadInst *LI) {
+ // process loads...
+ },
+ [] (AllocaInst *AI) {
+ // process allocas...
+ });
+
+Braced Initializer Lists
+""""""""""""""""""""""""
+
+With C++11, there are significantly more uses of braced lists to perform
+initialization. These allow you to easily construct aggregate temporaries in
+expressions among other niceness. They now have a natural way of ending up
+nested within each other and within function calls in order to build up
+aggregates (such as option structs) from local variables. To make matters
+worse, we also have many more uses of braces in an expression context that are
+*not* performing initialization.
+
+The historically common formatting of braced initialization of aggregate
+variables does not mix cleanly with deep nesting, general expression contexts,
+function arguments, and lambdas. We suggest new code use a simple rule for
+formatting braced initialization lists: act as-if the braces were parentheses
+in a function call. The formatting rules exactly match those already well
+understood for formatting nested function calls. Examples:
+
+.. code-block:: c++
+
+ foo({a, b, c}, {1, 2, 3});
+
+ llvm::Constant *Mask[] = {
+ llvm::ConstantInt::get(llvm::Type::getInt32Ty(getLLVMContext()), 0),
+ llvm::ConstantInt::get(llvm::Type::getInt32Ty(getLLVMContext()), 1),
+ llvm::ConstantInt::get(llvm::Type::getInt32Ty(getLLVMContext()), 2)};
+
+This formatting scheme also makes it particularly easy to get predictable,
+consistent, and automatic formatting with tools like `Clang Format`_.
+
+.. _Clang Format: http://clang.llvm.org/docs/ClangFormat.html
+
+Language and Compiler Issues
+----------------------------
Treat Compiler Warnings Like Errors
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
code.
That said, LLVM does make extensive use of a hand-rolled form of RTTI that use
-templates like `isa<>, cast<>, and dyn_cast<> <ProgrammersManual.html#isa>`_.
+templates like :ref:`isa\<>, cast\<>, and dyn_cast\<> <isa>`.
This form of RTTI is opt-in and can be
:doc:`added to any class <HowToSetUpLLVMStyleRTTI>`. It is also
substantially more efficient than ``dynamic_cast<>``.
Unfortunately, not all compilers follow the rules and some will generate
different symbols based on whether ``class`` or ``struct`` was used to declare
-the symbol. This can lead to problems at link time.
+the symbol (e.g., MSVC). This can lead to problems at link time.
+
+* All declarations and definitions of a given ``class`` or ``struct`` must use
+ the same keyword. For example:
+
+.. code-block:: c++
+
+ class Foo;
+
+ // Breaks mangling in MSVC.
+ struct Foo { int Data; };
+
+* As a rule of thumb, ``struct`` should be kept to structures where *all*
+ members are declared public.
+
+.. code-block:: c++
+
+ // Foo feels like a class... this is strange.
+ struct Foo {
+ private:
+ int Data;
+ public:
+ Foo() : Data(0) { }
+ int getData() const { return Data; }
+ void setData(int D) { Data = D; }
+ };
+
+ // Bar isn't POD, but it does look like a struct.
+ struct Bar {
+ int Data;
+ Bar() : Data(0) { }
+ };
+
+Do not use Braced Initializer Lists to Call a Constructor
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+In C++11 there is a "generalized initialization syntax" which allows calling
+constructors using braced initializer lists. Do not use these to call
+constructors with any interesting logic or if you care that you're calling some
+*particular* constructor. Those should look like function calls using
+parentheses rather than like aggregate initialization. Similarly, if you need
+to explicitly name the type and call its constructor to create a temporary,
+don't use a braced initializer list. Instead, use a braced initializer list
+(without any type for temporaries) when doing aggregate initialization or
+something notionally equivalent. Examples:
+
+.. code-block:: c++
+
+ class Foo {
+ public:
+ // Construct a Foo by reading data from the disk in the whizbang format, ...
+ Foo(std::string filename);
+
+ // Construct a Foo by looking up the Nth element of some global data ...
+ Foo(int N);
+
+ // ...
+ };
+
+ // The Foo constructor call is very deliberate, no braces.
+ std::fill(foo.begin(), foo.end(), Foo("name"));
+
+ // The pair is just being constructed like an aggregate, use braces.
+ bar_map.insert({my_key, my_value});
+
+If you use a braced initializer list when initializing a variable, use an equals before the open curly brace:
-So, the rule for LLVM is to always use the ``class`` keyword, unless **all**
-members are public and the type is a C++ `POD
-<http://en.wikipedia.org/wiki/Plain_old_data_structure>`_ type, in which case
-``struct`` is allowed.
+.. code-block:: c++
+
+ int data[] = {0, 1, 2, 3};
+
+Use ``auto`` Type Deduction to Make Code More Readable
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Some are advocating a policy of "almost always ``auto``" in C++11, however LLVM
+uses a more moderate stance. Use ``auto`` if and only if it makes the code more
+readable or easier to maintain. Don't "almost always" use ``auto``, but do use
+``auto`` with initializers like ``cast<Foo>(...)`` or other places where the
+type is already obvious from the context. Another time when ``auto`` works well
+for these purposes is when the type would have been abstracted away anyways,
+often behind a container's typedef such as ``std::vector<T>::iterator``.
+
+Beware unnecessary copies with ``auto``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The convenience of ``auto`` makes it easy to forget that its default behavior
+is a copy. Particularly in range-based ``for`` loops, careless copies are
+expensive.
+
+As a rule of thumb, use ``auto &`` unless you need to copy the result, and use
+``auto *`` when copying pointers.
+
+.. code-block:: c++
+
+ // Typically there's no reason to copy.
+ for (const auto &Val : Container) { observe(Val); }
+ for (auto &Val : Container) { Val.change(); }
+
+ // Remove the reference if you really want a new copy.
+ for (auto Val : Container) { Val.change(); saveSomewhere(Val); }
+
+ // Copy pointers, but make it clear that they're pointers.
+ for (const auto *Ptr : Container) { observe(*Ptr); }
+ for (auto *Ptr : Container) { Ptr->change(); }
Style Issues
============
As an exception, classes that mimic STL classes can have member names in STL's
style of lower-case words separated by underscores (e.g. ``begin()``,
-``push_back()``, and ``empty()``).
+``push_back()``, and ``empty()``). Classes that provide multiple
+iterators should add a singular prefix to ``begin()`` and ``end()``
+(e.g. ``global_begin()`` and ``use_begin()``).
Here are some examples of good and bad names:
.. code-block:: c++
- assert(Ty->isPointerType() && "Can't allocate a non pointer type!");
+ assert(Ty->isPointerType() && "Can't allocate a non-pointer type!");
assert((Opcode == Shl || Opcode == Shr) && "ShiftInst Opcode invalid!");
individual enumerators. To suppress this warning, use ``llvm_unreachable`` after
the switch.
-Use ``LLVM_DELETED_FUNCTION`` to mark uncallable methods
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Prior to C++11, a common pattern to make a class uncopyable was to declare an
-unimplemented copy constructor and copy assignment operator and make them
-private. This would give a compiler error for accessing a private method or a
-linker error because it wasn't implemented.
-
-With C++11, we can mark methods that won't be implemented with ``= delete``.
-This will trigger a much better error message and tell the compiler that the
-method will never be implemented. This enables other checks like
-``-Wunused-private-field`` to run correctly on classes that contain these
-methods.
-
-To maintain compatibility with C++03, ``LLVM_DELETED_FUNCTION`` should be used
-which will expand to ``= delete`` if the compiler supports it. These methods
-should still be declared private. Example of the uncopyable pattern:
-
-.. code-block:: c++
-
- class DontCopy {
- private:
- DontCopy(const DontCopy&) LLVM_DELETED_FUNCTION;
- DontCopy &operator =(const DontCopy&) LLVM_DELETED_FUNCTION;
- public:
- ...
- };
-
Don't evaluate ``end()`` every time through a loop
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Most of the time, you probably have no reason to flush the output stream, so
it's better to use a literal ``'\n'``.
+Don't use ``inline`` when defining a function in a class definition
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+A member function defined in a class definition is implicitly inline, so don't
+put the ``inline`` keyword in this case.
+
+Don't:
+
+.. code-block:: c++
+
+ class Foo {
+ public:
+ inline void bar() {
+ // ...
+ }
+ };
+
+Do:
+
+.. code-block:: c++
+
+ class Foo {
+ public:
+ void bar() {
+ // ...
+ }
+ };
+
Microscopic Details
-------------------
In general, we strive to reduce indentation wherever possible. This is useful
because we want code to `fit into 80 columns`_ without wrapping horribly, but
-also because it makes it easier to understand the code. Namespaces are a funny
-thing: they are often large, and we often desire to put lots of stuff into them
-(so they can be large). Other times they are tiny, because they just hold an
-enum or something similar. In order to balance this, we use different
-approaches for small versus large namespaces.
-
-If a namespace definition is small and *easily* fits on a screen (say, less than
-35 lines of code), then you should indent its body. Here's an example:
-
-.. code-block:: c++
-
- namespace llvm {
- namespace X86 {
- /// \brief An enum for the x86 relocation codes. Note that
- /// the terminology here doesn't follow x86 convention - word means
- /// 32-bit and dword means 64-bit.
- enum RelocationType {
- /// \brief PC relative relocation, add the relocated value to
- /// the value already in memory, after we adjust it for where the PC is.
- reloc_pcrel_word = 0,
-
- /// \brief PIC base relative relocation, add the relocated value to
- /// the value already in memory, after we adjust it for where the
- /// PIC base is.
- reloc_picrel_word = 1,
-
- /// \brief Absolute relocation, just add the relocated value to the
- /// value already in memory.
- reloc_absolute_word = 2,
- reloc_absolute_dword = 3
- };
- }
- }
-
-Since the body is small, indenting adds value because it makes it very clear
-where the namespace starts and ends, and it is easy to take the whole thing in
-in one "gulp" when reading the code. If the blob of code in the namespace is
-larger (as it typically is in a header in the ``llvm`` or ``clang`` namespaces),
-do not indent the code, and add a comment indicating what namespace is being
-closed. For example:
+also because it makes it easier to understand the code. To facilitate this and
+avoid some insanely deep nesting on occasion, don't indent namespaces. If it
+helps readability, feel free to add a comment indicating what namespace is
+being closed by a ``}``. For example:
.. code-block:: c++
} // end namespace knowledge
} // end namespace llvm
-Because the class is large, we don't expect that the reader can easily
-understand the entire concept in a glance, and the end of the file (where the
-namespaces end) may be a long ways away from the place they open. As such,
-indenting the contents of the namespace doesn't add any value, and detracts from
-the readability of the class. In these cases it is best to *not* indent the
-contents of the namespace.
+
+Feel free to skip the closing comment when the namespace being closed is
+obvious for any reason. For example, the outer-most namespace in a header file
+is rarely a source of confusion. But namespaces both anonymous and named in
+source files that are being closed half way through the file probably could use
+clarification.
.. _static:
.. code-block:: c++
namespace {
- class StringSort {
- ...
- public:
- StringSort(...)
- bool operator<(const char *RHS) const;
- };
+ class StringSort {
+ ...
+ public:
+ StringSort(...)
+ bool operator<(const char *RHS) const;
+ };
} // end anonymous namespace
static void runHelper() {
.. code-block:: c++
namespace {
+
class StringSort {
...
public:
See Also
========
-A lot of these comments and recommendations have been culled for other sources.
+A lot of these comments and recommendations have been culled from other sources.
Two particularly important books for our work are:
#. `Effective C++
projects / oota-llvm.git / blobdiff