-
Notifications
You must be signed in to change notification settings - Fork 808
Coding Standards
[This document reuses content from a number of sources. Implicit thanks to the otherwise uncredited original authors and contributors.]
The WinObjC engineering team values consistency and clarity as a way to promote correctness, quality, and maintainability of our codebase. To that end, this document lays out foundational standards for writing Objective C and C++ code in our project.
The Objective C guidance in this document is meant to augment existing industry guidance, so please read through Apple's Coding Guidelines for Cocoa before digesting the rest of the standards outlined below.
This document is organized with a set of "best practices" bullet points in each top-level section, followed by subsections containing additional details, examples, and guidance.
If you read only this overview, plus the top-level sections, you will have a pretty good idea of how to write code that follows WinObjC team conventions.
Produce high quality, self-documenting code - code that is primarily for the reader, not the writer.
Write code that benefits from the dynamic nature of Objective C, while also leveraging the richness provided by modern C++ where practical.
Use the STL and RAII patterns; be purposeful with exception-handling and usage.
Continually move the needle forward so that we're always improving our codebase.
The conventions in this document apply to all new Objective C and C++ code written in this group. "New code" also encompasses existing code that you are modifying. Adherence is valued above consistency with surrounding code, at all levels of granularity.
Large bodies of existing code should be brought into conformance as the code is modified (this is essentially our team's starting point). However, any publicly-facing portions (interfaces, inter-module constructs, etc.) should be brought into line as soon as possible, so that a ripple effect from them doesn't infect other code and force our new code into non-compliance.
Cutting and pasting, or copying files from an existing codebase into our projects must first be updated to reflect the conventions required by this document.
These conventions apply to non-production code (i.e., unit tests, tools) just as they do for production code.
Adherence to the conventions in this document is enforceable via code review, and by the use of our ClangFormat scripts. Please take active part in code reviews in order to help encourage and maintain a consistent codebase.
In addition to the below coding format rules, code should always be formatted using ClangFormat before sending it out for review.
This section describes code layout and formatting requirements.
-
No hard tabs; use spaces with a tabstop of 4 characters.
-
Lines must not exceed 140 characters.
-
All code files must contain the Microsoft copyright/MIT license banner.
-
Bracing style is most similar to the Stroustrup variant of the K&R style.
-
Braces are mandatory even when the compiler would not require them (no single-line conditionals).
-
Parenthesis are highly encouraged to group conditionals even where the compiler would not require them.
-
Use "" and <> correctly in #include and #import directives.
-
The 'auto' keyword is encouraged under specific conditions.
-
Prefer C++ language types over Win32 SHOUTY types.
-
Use the override keyword and omit the virtual keyword when doing so
-
Use nullptr rather than NULL.
-
Use '\0' rather than 0 for C string null terminators.
-
No space between a typename and any associated pointer, hat, or reference symbols.
-
Prefer to put code into .cpp/.mm files when possible.
-
Leverage namespaces (for C++) and standard namespace-style prefixes (for Objective C) to group portions of related code.
-
Prefer C++ casts rather than C casts for better type safety.
-
Prefer const values over #define constants for better type safety.
-
Use macros with discretion.
Beyond the above, certain additional formatting requirements are described by example in the sections that below. There are also examples with additional discussion and clarification for some of the above requirements.
All first-party and modified third-party code files must contain at least the below Microsoft copyright/MIT license banner. If additional attribution is applicable, be sure to include that as well.
Note: Our codebase is comprised of code from various third-parties which usually already include a banner. Do Not replace any such banners with the header below, but Do Add the Microsoft copyright to the banner if a modification is made to the file.
//******************************************************************************
//
// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
//
// This code is licensed under the MIT License (MIT).
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
//******************************************************************************Our bracing style is most similar to the Stroustrup variant of the K&R style. Open-braces go on the same line as the statement control statement, class name, function name, etc. However, the closing brace always goes on its own line, unless it's 'cuddled' against an else statement.
if (a == b) { // Correct
...
}
if (a == b) // Incorrect - opening brace goes on the same line as the control statement
{
...
}
if (a == b) { ... } // Incorrect - code and closing braces go on their own lines
if (a == b) {
...
} else if (b < a) { // Correct else placement
...
}
if (a == b) {
...
}
else if (b < a) { // Incorrect - else should be 'cuddled' on the previous line
...
}
Always uses braces to indicate the scope of a given body of code. This prevents easily avoidable bugs such as the infamous "goto fail" SSL security flaw.
if (a == b) { // Correct
C();
}
if (a == b) // Incorrect - missing braces
C();
if (a == b) C(); // Incorrect - missing bracesAlso, always brace around case clauses that introduce variables. This prevents confusing scenarios where variables may not be initialized while looking like they are.
Prefer the use of the auto keyword when the type on the lefthand side of an assignment is redundant, because the type is also clearly specified on the righthand side.
Use of auto is also encouraged where it genuinely improves code readability (for STL iterators, etc.), or where absolutely required because code would not compile without it (if a type is not explicitly expressible by the programmer, for example).
Enforcement must err on the side of excluding the use of auto - under-use is deemed better than over-use.
// Not allowed - the type of the variable is not clear
auto count = 7;
auto name = "name";
auto model = foo.getTheModel();
// Correct
int count = 7;
const char* name = "name";
auto model = std::make_shared<Model>();
auto message = ref new Platform::String("The message");
auto foo = reinterpret_cast<Foo*>(bar);
// OK -- the alternative is just too painful
// for (const std::pair<std::wsstring, std::vector<std::pair<int, std::shared_ptr<Foo>>>>::iterator &mapEntry : map)
std::unordered_map<std::wsstring, std::vector<std::pair<int, std::shared_ptr<Foo>>>> map;
for (auto& mapEntry : map) {
// ...
}
// OK -- type is not expressable
auto lambda = []() -> void {};init methods should be placed at the top of the implementation, directly after the @synthesize and @dynamic statements. dealloc should be placed directly below the init methods of any class. In files with ARC disabled, dealloc must call super's dealloc at the end of its implementation.
Init methods should be structured as follows:
- (instancetype)init {
if (self = [super init]) { // Or call the designated initializer
// Perform class-specific init
}
return self;
}See Apple's initialization documentation for more info.
ARC variable qualifiers (__strong, __weak, __unsafe_unretained, __autoreleasing) should be placed before the variable name.
NSString* __weak name;For readability purposes, use "header.h" when referring to a header which is local to the project of the includer. Use <header.h> when referring to a header which is not local to project of the includer.
When declaring a set of variables, the members of a class, or any other sequence of defined objects, avoid vertically aligning the names of the variables. The quick reader should not need to scan horizontally to find the name of the local whose type is "int":
// Incorrect - too many spaces between the type and the instance name
int local1;
HANDLE localHandle2;
ReallyLongTypeNameHere local3;
struct Zoom {
int size;
HANDLE fileTarget;
};
// Correct
int local1;
HANDLE localHandle2;
ReallyLongTypeNameHere local3;
struct Zoom {
int size;
HANDLE fileTarget;
};Add overall method/function comments to their declarations, but additional commenting can be added to their definitions as needed.
Adequately comment implementation details as-needed via regular C++ style comments.
Avoid adding comments next to code on the same line - instead, prefer to place comments on the previous line (with the exception of documenting large function call arguments).
If there are general comments that apply to a method implementation, they can go above the implementation:
Foo.h:
// No need to comment here, as it's pretty obvious what this method does.
// However, it may be desirable to comment initialization specifics in some cases.
void initialize();
Foo.cpp:
// This block is optional, but extra comments here are ok as long as they're not identical to the
// comments in the method declaration.
void initialize() {
// Implementation detail
doSomething();
// Another implementation detail
doSomethingElse();
}Use C++ types; avoid using 'shouty' Win32 types. Interop concerns, however, can override this guideline.
// Correct
int fooValue;
unsigned long long barThing;
size_t count;
void foo(int x);
bool flag;
// Incorrect - prefer C++ types
ULONG barThing;
SIZE_T count;
DWORD thing;
QWORD otherThing;
TCHAR character;
LPWSTR wideStr;// Correct
int** outCount;
Foo^ foo;
MyStruct& s;
MyStruct& DoSomething(Foo^ foo);
std::vector<Foo^> m_vector;
// Incorrect
int **outCount;
int * count;
Foo ^ foo;
Foo ^foo;
MyStruct &s;
MyStruct & s;
MyStruct &doSomething(Foo ^foo);
std::vector<Foo ^> m_vector;Nested namespace declarations should each get their own line, and should not create additional levels of indentation.
// Correct
namespace A {
namespace B {
namespace C {
class Foo {
...
}
}
}
}
// Incorrect
namespace A {
namespace B {
namespace C {
class Foo {
...
}
}
}
}
// Incorrect
namespace A { namespace B { namespace C {
class Foo {
...
}
}}}Prefer C++ casts rather than C casts in all cases. C++ casts are more explicit, give finer-grained control, and express the intent of the code more clearly. There are three types of C++ casts we should be using:
-
static_cast handles related types such as one pointer to another in the same hierarchy.
-
reinterpret_cast handles conversion between unrelated types.
-
const_cast is used to cast away the 'const'ness of an object.
Note: Don't use 'const_cast' unless absolutely necessary; having to use 'const_cast' typically means that an API is not using 'const' appropriately. However, the Win32 API doesn't always use 'const' for passing parameters, so it may be necessary to use const_cast when using the Win32 API.
Note: 'const_cast' doesn't apply to Objective C objects, as there's no such thing as a 'const NSObject*', etc.
Further reading:
-
Sutter, H. (2005). - C++ Coding Standards - "Item 94: Avoid casting away const."
-
Sutter, H. (2005). - C++ Coding Standards - "Item 95: Don't use C-style casts."
Define named constant values as 'const' values rather than via macros when possible, to provide the added benefit of type safety.
Also consider leveraging enum classes for grouped constant values.
// Correct
const int c_defaultIndex = 3;
// Incorrect
#define DEFAULT_INDEX 3Further reading:
- Sutter, H. (2005). - C++ Coding Standards - "Item 15: Use const proactively."
Use macros only when they are absolutely necessary. Most functionality that is typically achieved through macros can be implemented through other C++ constructs (using constants, enums, inline functions, or templates) which will yield clearer, more resilient, more debuggable code.
This section covers variable names, function names, type names, etc.
-
Objective C code should follow Apple's naming guidelines in addition to the applicable guidance listed in this document.
-
Class and namespace names are based on PascalCasing.
-
Function and variable names are based on camelCasing.
-
Non-public function and variable names must start with an underscore.
-
Avoid using abbreviations.
-
Only simple loop counter variables may be single letters.
-
Hungarian notation is prohibited.
-
Class names must not have a C prefix or have "Class" in them.
-
Interface names must start with I and not have "Interface" in them.
-
Avoid typedefs and aliases for simple types (where not required for interop with Objective C clients).
-
SHOUTY_NAMES are only allowed (and required) for preprocessor macros.
The sections that follow provide examples and additional discussion.
Hungarian is not allowed. The light prefixing convention described in this section for certain variable types is not Hungarian, despite superficial similarities.
Code should be clear and concise, but clarity should not suffer. Some abbreviations may be well-known to you, but a new developer to the team or technology may not easily recognize them. It's best to avoid abbreviations when possible.
See the Apple docs for further guidance on proper Objective C naming guidelines.
// Correct
int id; // Common abbreviation for 'identifier'
const char* name;
int current;
timespec time;
NSTimeInterval date;
char* params;
// OK - although more descriptive names are preferred
int curVal; // Ok; common abbreviation for 'current value'
int ret; // Ok; common abbreviation for 'return value'
Foo* obj; // Ok; common abbreviation for 'object'
// Incorrect
int val;
const char* str;
int cur;
timespec t;
NSTimeInterval d;For out parameters, do prefix your variable names with 'out' to help clarify the parameter's usage.
Do not use 'p' as a prefix for pointer types, as that doesn't work well with smart pointers, C++/CX hats, or Objective C pointers which don't historically use the 'p' prefix.
No further prefixes are used for raw strings (no 'sz', 'psz', etc.)
Use the "_" prefix on all data members of Objective C and C++ classes. This is consistent with Objective C instance variables that are synthesized automatically by the compiler.
If the compiler can synthesize your Objective C variable automatically, then let it.
Use the "_" prefix on private and protected methods of C++ and Objective C classes.
class Foo {
public:
void doFoo();
private:
int _count;
wstring _name;
void _moop();
int _zeem();
};If you need behaviors beyond simple initialization of fields in a constructor, use a class.
No prefix is allowed on fields in a structure.
struct Foo {
size_t size;
int count;
const char* name;
};Do use PascalCasing for types and namespaces. This pattern capitalizes the first letter of each logical word in a name. Do not add underscores between word-pieces in a name.
Do use camelCasing for functions and variables (parameters, local variables, etc.). This pattern capitalizes the first letter of each logical word in a variable name, except the first. Note that this means that single-word names are lower-case, and that prefixed variables (s_, c_, etc.) have the pattern s_camelCase.
Do not confuse words with syllables. UndoOperation makes sense as function name; UnDoOperation does not.
Such as:
for (int i = 0; i < 10; i++) {
}Static and global variables name must start with "s_". The remainder of the variable follows the standard camelCasing rules. This helps flag the variable as static (not thread safe, singleton, etc.).
Use "c_" for constants (e.g. variables with "static const" C++ qualifier). The remainder of the variable follows the standard camelCasing rules. Exceptions will be made for interop.
There is no need to combine "c_" with other prefixes ("sc", etc).
Consistency within a single directory or source file is important.
-
Class names must not start with the "C" prefix.
-
Use "struct Foo{};" instead of "typedef struct FOO {} Foo;" where not required for interop with Objective C clients.
-
Interfaces (like COM, or C++ types that have only "virtual Foo() = 0" members) must start with the "I" prefix. ("IBar" is valid, "Bar" is not)
-
Creating new SHOUTY_TYPE_NAMES is prohibited; ALL_CAPS is reserved for macros.
-
Do not include "Class" or "Interface" in names - "Bar" instead of "BarClass", "IFoo" not "IFooInterface"
Overuse of typedefs and aliases can easily lead to confusing code. However, function types are usually exempt from this guidance.
// correct
std::vector<id> _ids;
...
std::vector<id>& getIds();
using MyCallback = void (*)(int, const std::string&); // Ok, as MyCallback is much nicer to use
virtual void subscribe(const MyCallback& callback);
// incorrect
using IdContainer = std::vector<id>;
IdContainer _ids;
...
IdContainer& getIds();Macro names should be all capitalized, with underscores between words.
// correct
#define THROW_IF_FAILED(operation)
// incorrect
#define ThrowIfFailed(operation) - should be all caps
#define THROWIFFAILED(operation) - missing underscoresObjective C code should follow Apple's coding guidelines in addition to the applicable guidance listed in this document.
-
All code should compile for Objective C++ or C++.
-
Always use 'self.' when accessing your own public Objective C properties.
-
Declare variables as locally as possible.
-
Initialize variables when they are declared, and on a single line where possible*.*
-
Prefer C++ references over raw pointers when ownership is not required.
-
Prefer smart pointers over raw pointers in nearly all other cases.
-
Avoid accepting non-const C++ references as arguments to public methods.
-
Do not invent your own containers, locks, etc. where the STL or Foundation types will suffice.
-
Use enum classes (aka scoped enums) instead of unscoped enums.
-
Use range-based for loops when possible. This includes ObjC's enumerator loops.
-
Avoid the use of gotos; use RAII constructs instead.
-
Prefer deleted functions to private undefined ones.
-
Prefer alias declarations to typedefs.
Use Objective C property definitions rather than raw instance variables for public fields. Do not expose ivars publicly. Private ivars should be declared in the implementation file or an internal header for the extension class, when used across classes.
// Correct
@interface MyObject: NSObject
@property (nonatomic) NSString* name;
@end
// Incorrect
@interface MyObject: NSObject {
NSString* name;
}Use direct access to instance variables under the following circumstances:
-
Within initializer methods (init, etc.) and delloc methods.
-
From within custom property setters and getters.
-
When the public property type differs from the type of the actual backing variable, and access to the backing variable's functionality is necessary. For example, a class may expose a public NSArray property, yet still wish to modify its contents internally. In such cases, the class will need to store an NSMutableArray variable internally, and access it directly when any array modifications are necessary.
-
For any private or otherwise internal state.
See more information in Apple's documentation.
Always use 'self.' when accessing your own public properties. Certain properties will be externally observed, expecting callbacks on state change.
Do declare variables as locally as possible. This makes the code much easier to read, and also reduces the chance of coding errors.
Prefer to initialize variables when they are declared, and on a single line (where the language allows it).
Further reading:
- Sutter, H. (2005). - C++ Coding Standards - "Item 18: Declare variables as locally as possible."
- Sutter, H. (2005). - C++ Coding Standards - "Item 19: Always initialize variables."
Lifetime ownership is rarely clear when passing around raw pointers; using a C++ reference is much more clear.
class Node {
private:
Node& _parent; // Correct - _parent ownership is clearly handled elsewhere.
INode& _root; // Correct - _root ownership is clearly handled elsewhere, even for interface types.
}
class Node {
private:
Node* _parent; // Incorrect - _parent ownership is not clear; do I need to free it in my dtor?
INode* _root; // Incorrect - _root ownership is not clear; do I need to free it in my dtor?
}Passing raw pointers between objects makes it unclear who is responsible for freeing the pointer. Modern code dictates that smart pointers should be used instead of raw pointers in nearly all cases, leading to safer and more clear code. See the RAII section for more details.
Note: Special cases to this rule do still exist, but such cases are usually self-contained within a given class implementation/compilation unit. For example, a .wav file parser would clearly need to work with raw pointers to locations within a mapped audio file, but such usage would not need to bleed out to other components.
class Node {
private:
std::weak_ptr<Node> _parent; // Correct - _parent ownership is clearly handled independently of this object's lifetime.
std::weak_ptr<INode> _root; // Correct - _root ownership is clearly handled independently of this object's lifetime.
WRL::WeakRef _root; // Correct - _root ownership is clearly handled independently of this object's lifetime.
}
class View {
private:
std::shared_ptr<Node> _root; // Correct - _root ownership is clearly shared across multiple objects.
std::unique_ptr<IDataSource> _source; // Correct - _source ownership is clearly self-contained within this View.
WRL::ComPtr<IDataSource> _source; // Correct - _source ownership is clearly self-contained within this View.
}
class Node {
private:
Node* _parent; // Incorrect - _parent ownership is not clear; do I need to free it in my dtor?
INode* _root; // Incorrect - _root ownership is not clear; do I need to free it in my dtor?
}
class View {
private:
Node* _root; // Incorrect - _root ownership is not clear; do I need to free it in my dtor?
IDataSource* _source; // Incorrect - _source ownership is not clear; do I need to free it in my dtor?
}Aliases support template arguments.
Further reading:
- Meyers, S. (2015). - Effective Modern C++ - "Item 19: Use std::shared_ptr for shared-ownership resource management."
Start with a unique_ptr if you're unsure whether or not you need to share ownership of a resource with other components -- this is usually the correct choice. The nice thing about exclusive ownership is that the shutdown is deterministic, which allows you to provide temporary controlled access to your exclusive resource via a strong C++ reference.
class Bar {
public:
void doSomething(const Node& node);
}
class Foo {
private:
std::unique_ptr<Node> _root;
std::unique_ptr<Bar> _listener;
void update()
{
_listener->doSomething(*_root); // Passing a controlled reference into _listener
}
}Further reading:
- Meyers, S. (2015). - Effective Modern C++ - "Item 18: Use std::unique_ptr for exclusive-ownership resource management."
Use std::shared_ptr if you must share ownership with multiple components, of if you need to hand out std::weak_ptrs to a resource to avoid cyclic dependencies.
Further reading:
- Meyers, S. (2015). - Effective Modern C++ - "Item 19: Use std::shared_ptr for shared-ownership resource management."
COM usage isn't common in our code, but if you must call into a COM API, all COM pointer usage must be wrapped in WRL::ComPtrs at all times.
TODO: Write up examples/guidance for smart handle usage.
TODO: Write up examples/guidance for scopeexit usage; include in 'goto' cleanup example.
TODO: Write up justification/guidance, how to use RAII to avoid the need for gotos, etc.
__TODO: Write up guidance; ARC, usage of variable qualifiers (unsafe_unretained, etc.).
Each file which enables ARC, must #include/import the header "AssertARCEnabled.h". This will generate a compile time error if ARC is ever turned OFF for that file and prevent this feature from being accidentally turned OFF.
4.4.1 Pass smart pointers into methods by const reference, return smart pointers by value when possible
// Correct
CComPtr<IMyInterface> getFoo(); // Throws on failure
HRESULT tryGetFoo(IMyInterface** outInterface); // Returns error on failure
HRESULT tryDoSomethingWithFoo(const CComPtr<IMyInterface>& interface); // Allows ownership acquisition by the callee
HRESULT tryDoSomethingWithFoo(IMyInterface& interface); // Discourages ownership acquisition by the callee
// Incorrect
HRESULT getFoo(CComPtr<IMyInterface>& myInterface);
HRESULT getFoo(CComPtr<IMyInterface>* myInterface);
HRESULT doSomethingWithFoo(CComPtr<IMyInterface> myInterface); // Unnecessary addref/release
HRESULT doSomethingWithFoo(const CComPtr<IMyInterface> myInterface); // Unnecessary addref/release - and never pass by-value const.Except for at ABI boundaries, use C++ references whenever possible, and avoid raw pointers.
This is true for even mutable method arguments, but such cases should rarely be encountered publicly, because methods can and should return values instead of having 'out' params. Use STL's pair, tuple, or custom structs to return compound values.
// Correct
int GetFoo();
const std::wstring& getName();
std::pair<Foo, Bar> getValue();
MyStruct getValue();
bool inspectMyStructForSomeCondition(const MyStruct& value);
// Ok
bool populate(MyStruct& value); // Ok, but odd on a public method. Populates the struct.
bool populateIfExists(MyStruct* value); // Ok, but odd on a public method. Populates the struct if non-null.
// Incorrect
void getFoo(int* pFoo); // Should return int
void getFoo(int& foo); // Should return int
void getName(std::wstring* value); // Should return std::wstring
void getName(std::wstring& value); // Should return std::wstring
Foo getValue(Bar* value); // Should return e.g. std::pair<Foo, Bar> or similar construct
Foo getValue(Bar& value); // Should return e.g. std::pair<Foo, Bar> or similar construct
void getValue(Foo* found, Bar* value); // Should return e.g. std::pair<Foo, Bar> or similar constructFor internal use, resources should be encapsulated in smart types (e.g. STL containers or constructs), instances of which are passed around by reference. However, C++ types should not be passed across certain boundaries; resources must be unwrapped and accepted and returned in raw form. The definition of a boundary depends on context; in general a publicly consumable COM object is a boundary, as is a DLL.
// Correct
class SomePublicFacingClass {
void somePublicFacingCall(char* data, size_t len);
};
// Incorrect - unsafe
class SomePublicFacingClass {
void somePublicFacingCall(std::vector<char>& data); // Incorrect - unsafe
};C++ supports multiple inheritance and certain common patterns rely heavily on this language feature. The most obvious example is COM, where multiple interface inheritance is used routinely (although COM will not be very commonly used in our codebase).
Multiple implementation inheritance, on the other hand, is confusing, leading to issues such as the diamond problem, casting ambiguities, and constructor ordering issues. Do not use it in new code. Instead, consider design patterns involving encapsulation and interfaces.
Bottom line: inherit from at most one concrete class, and any number of interface classes.
Use assertions liberally, but be careful to distinguish between what is an assertion and what is a run-time error.
Assertions always indicate programmer error or miscommunication; valid assertions include cases where an internal contract or invariant is violated or broken.
Assertions should never be used for a run-time error which your code could handle gracefully.
Assertions should never be used for a run-time error which is catastrophic/unrecoverable; use failfast semantics instead.
An assertion failure always indicates a bug in the code, whether it is triggered by end-user usage, self-host usage, or tests.
Incorrect assertions include (but are not limited to):
-
Before a conditional test that handles the same error condition.
-
Checking a pointer for being not nullptr (crashing is of higher diagnostic value than the assertion failure).
- Note: Given that sending messages to nil Objective C objects silently fails, asserts for non-nil are ok. However, prefer handling the error in code, returning an error to the caller, or using failfast semantics if any of those options make more sense.
-
Validating any input parameters to a function where the values may come from external sources (external component, user, registry, database, file, etc.).
-
Validating that a function succeeded or failed.
All of the above items should be converted from an ASSERT to the appropriate error handling and/or telemetry-logging mechanism, if not removed altogether.
The only allowed assertion macros are ASSERT and static_assert. Use static_assert wherever it's possible to perform the check at compile time.
Assertions hit under test always indicate bugs. Unit tests should not deliberately test for assertions.
TODO: Add guidance on when to assert vs. fail fast.
TODO: Add guidance on usage of unsupported/invalid_state macros.
TODO: Add guidance on our exception-handling strategy. When to use over HRESULTs, and vice-versa.
TODO: Add guidance on where to add exception guards to prevent leaked exceptions.
TODO: Add guidance on our error-code handling strategy; HRESULTs, etc. When to use over exceptions, and vice-versa.
Project
Using the bridge
- Getting Started
- Using vsimporter
- Using the SDK
- Building From Source
- Adding Objective C to an Existing Project
- UI Guidance
- Changing the SDK Version of a Project
- Debugging
- Debugging Stack Traces from Crash Dumps
- Supported Third Party Libraries
- Creating and Linking Against C++ Static Libraries
- Packaging
Samples and Tutorials
- Quick Start Tutorial
- Building a To-Do List App
- Building a Calculator App
- Mixing and Matching UIKit and XAML
- IOS Bridge Samples Repo
Contributing
Links