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425 lines
17 KiB
Plaintext
425 lines
17 KiB
Plaintext
Synergy Developer and Porting Guide
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===================================
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This document is under development.
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Code Organization
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-----------------
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The synergy source code organization is:
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. -- root makefiles, some standard documentation
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cmd -- program source code
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launcher -- synergy launcher for Windows
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synergyc -- synergy client
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synergys -- synergy server
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config -- stuff for autoconf/automake
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dist -- files for creating distributions
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nullsoft -- files for creating Nullsoft NSIS installer (Windows)
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rpm -- files for creating RPMs
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doc -- placeholder for documentation
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examples -- example files
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lib -- library source code
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arch -- platform dependent utility library
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base -- simple utilities
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client -- synergy client library
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common -- commonly needed header files
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io -- I/O
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mt -- multithreading
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net -- networking
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platform -- platform dependent display/window/event stuff
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server -- synergy server library
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synergy -- synergy shared client/server code library
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Note how the utility code required by the programs is placed into
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separate library directories. This makes the makefiles a little
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more awkward but makes for a cleaner organization. The top level
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directory has only the standard documentation files and the files
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necessary to configure and build the rest of the project.
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Coding Style Guide
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------------------
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Synergy uses many coding conventions. Contributed code should
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following these guidelines.
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- Symbol Naming
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Names always begin with a letter (never an underscore). The first
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letter of interior names are always capitalized. Acronyms should
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be all uppercase. For example: myTextAsASCII.
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Names come it two flavors: leading capital and leading lowercase.
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The former have the first character capitalized and the latter
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don't. In the following table, leading capital names are indicated
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by `Name' and leading lowercase names by `name'.
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The naming convention for various things are:
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* Exceptions -- X + Name XMyException
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* Interfaces -- I + Name IMyInterface
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* Template Classes -- T + Name TMyTemplate<>
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* Other Classes -- C + Name CMyClass
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* Enumerations -- E + Name EMyEnumeration
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* Constants -- k + Name kMyConstant
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* Data Members -- m_ + name m_myDataMember
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* Methods -- name myMethod
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* Functions -- name myFunction
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* Variables -- name myVariable
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Exceptions are types that get thrown and are generally derived
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(possibly indirectly) from XBase. Interfaces are derived (possibly
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indirectly) from IInterface and have only pure virtual functions.
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Other classes are classes that aren't exceptions or interfaces.
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Constants include global constants and enumerants.
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Method names should usually have the form `verbObject'. For example:
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* isGameOn()
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* getBeer()
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* pressPowerButton()
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* setChannel()
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In general, use `get' and `set' to read and write state but use `is'
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to read boolean state. Note that classes that contain only `is',
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`get', and `set' are probably plain old data; you might want to
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consider using public data members only or, better, refactor your
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design to have classes that actually do something more than just
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hold data.
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- File Naming
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Each class should have one source and one header file. If the
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class is named `CMyClass' then the source file should be named
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`CMyClass.cpp' and the header file `CMyClass.h'.
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Headers files not containing a class should have some meaningful
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name with a leading capital (e.g. `Version.h').
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Source files without a header file have a leading lowercase name.
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Only files containing the entry point for an application should
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lack a header file.
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- Dependencies
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* No circular library dependencies
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Library dependencies form an acyclic graph. Conceptually
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libraries can be arranged in layers where each library only
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references libraries in layers below it, not in the same layer
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or layers above it. The makefiles build the lowest layer
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libraries first and work upwards.
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* Avoid circular uses-a relationships
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When possible, design classes with one-way uses-a relationships
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and avoid cycles. This makes it easier to understand the code.
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However, sometimes it's not always practical so it is permitted.
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* Included files in headers
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Headers should #include only the necessary headers. In
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particular, if a class is referenced in a header file only as a
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pointer or a reference then use `class COtherClass;' instead of
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`#include "COtherClass.h".'
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* #include syntax
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Non-synergy header files must be included using angle brackets
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while synergy header files must be included using double quotes.
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#include "CSynergyHeader.h"
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#include <systemheader.h>
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The file name in a #include must not be a relative path unless
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it's a system header file and it's customary to use a relative
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path, e.g. `#include <sys/types.h>'. Use compiler options to
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add necessary directories to the include search path.
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* Included file ordering
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Files should be included in the following order:
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* Header for source file
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The first include for CMyClass.cpp must be CMyClass.h.
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* Other headers in directory, sorted alphabetically
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* Headers for each library, sorted alphabetically per library
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Include headers from the library closest in the dependency graph
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first, then the next farthest, etc. Sort alphabetically within
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each library.
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* System headers
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- C++
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* C++ features
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Synergy uses the following more recent C++ features:
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* bool
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* templates
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* exceptions
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* mutable
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* new scoping rules
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* the standard C++ library
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Do not use the following C++ features:
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* dynamic_cast
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* run time type information
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* namespaces and using (use std:: where necessary)
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The new scoping rules say that the scope of a variable declared
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in a for statement is limited to the for loop. For example:
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for (int i = 0; i < 10; ++i) {
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// i is in scope here
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}
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// i is not in scope here
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for (int i = -10; i < 0; ++i) {
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// an entirely new i is in scope here
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}
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// i is not in scope here
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This is used routinely in synergy, but only in for loops. There
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is a macro for `for' in lib/base/common.h when building under
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Microsoft Visual C++ that works around the fact that that compiler
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doesn't follow the new scoping rules. Use the macro if your
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compiler uses the old scoping rules.
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* Standard C++ library
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The standard C++ library containers should always be used in favor
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of custom containers wherever reasonable. std::string is used
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throughout synergy but only as the CString typedef; always use
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CString, never std::string except in the arch library. Synergy
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avoids using auto_ptr due to some portability problems. Synergy
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makes limited use of standard algorithms and streams but they can
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be freely used in new code.
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* Limited multiple inheritance
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Classes should inherit implementation from at most one superclass.
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Inheriting implementation from multiple classes can have unpleasant
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consequences in C++ due to it's limited capabilities. Classes can
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inherit from any number of interface classes. An interface class
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provides only pure virtual methods. Synergy breaks this rule in
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IInterface which implements the virtual destructor for convenience.
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* No globals
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Avoid global variables. All global variables must be static, making
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it visible only with its source file. Most uses of global variables
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are better served by static data members of a class. Global
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constants are permitted in some circumstances.
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Also avoid global functions. Use public static member functions in
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a class instead.
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These rules are violated by the main source file for each program
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(except that the globals are still static). They could easily be
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rewritten to put all the variables and functions into a class but
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there's little to be gained by that.
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* Private data only
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If a class is plain-old-data (i.e. it has no methods) all of its
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data members should be public. Otherwise all of its data members
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should be private, not public or protected. This makes it much
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easier to track the use of a member when reading code. Protected
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data is not allowed because `protected' is a synonym for `public
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to my subclasses' and public data is a Bad Thing. While it might
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seem okay in this limited situation, the situation is not at all
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limited since an arbitrary number of classes can be derived,
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directly or indirectly, from the class and any of those classes
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have full access to the protected data.
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* Plain old data
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A class that merely contains data and doesn't perform operations
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on that data (other than reads and writes) is plain old data (POD).
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POD should have only public data members and non-copy constructors.
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It must not have any methods other than constructors, not even a
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destructor or assignment operators, nor protected or private data.
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Note that this definition of POD is not the definition used in the
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C++ standard, which limits the contained data types to types that
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have no constructors, destructors, or methods.
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* Avoid using friend
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Avoid declaring friend functions or classes. They're sometimes
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necessary for operator overloading. If you find it necessary to
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add friends to some class C, consider creating a utility class U.
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A utility class is declared as the only friend of C and provides
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only static methods. Each method forwards to a private method on
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an object of C type (passed as a parameter to the U's method).
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This makes maintenance easier since only U has friend access to C
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and finding any call to U is trivial (they're prefixed by U::).
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* Don't test for NULL when using `delete' or `delete[]'
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It's unnecessary since delete does it anyway.
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- Makefiles
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Automake's makefiles (named Makefile.am) have a few requirements:
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* Define the following macros at the top of the file:
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NULL =
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DEPTH = <relative-path-to-top-level>
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VDEPTH = ./$(VPATH)/$(DEPTH)
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<relative-path-to-top-level> is `..', `../..', `../../..', etc,
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whichever references the top directory of the synergy tree. For
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example, for a subdirectory of the top level use `..', for a
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subdirectory of a subdirectory of the top level use `../..'.
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* Lists should have one item per line and end in $(NULL). For
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example:
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EXTRA_DIST = \
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kiwi.txt \
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mango.cpp \
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papaya.h \
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$(NULL)
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Indentation must use tabs in a makefile. Line continuations
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(backslashes) should be aligned using tabs.
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* Lists of files should be sorted alphabetically. Lists of
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subdirectories must be in the desired build order.
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- Source Formatting
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Every project has its own formatting style and no style satisfies
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everyone. New code should be consistent with existing code:
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* All files should include the copyright and license notice
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* Use tabs to indent
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* Tabs are 4 columns
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* Lines should not extend past the 80th column
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* Open braces ({) go on same line as introducing statement
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`for (i = 0; i < 10; ++i) {' not
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for (i = 0; i < 10; ++i)
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{
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* Close braces line up with introducing statement
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* Open brace for function is on a line by itself in first column
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* Close brace for function lines up with open brace
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* Always use braces on: if, else, for, while, do, switch
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* `else {' goes on its own line
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* Always explicitly test pointers against NULL
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e.g. `if (ptr == NULL)' not `if (ptr)'
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* Always explicitly test integral values against 0
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e.g. `if (i == 0)' not `if (i)'
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* Put spaces around binary operators and after statements
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e.g. `if (a == b) {' not `if(a==b){'
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* C'tor initializers are one per line, indented one tab stop
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* Other indentation should follow existing practice
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* Use Qt style comments for extraction by doxygen (i.e. //! and /*!)
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* Mark incomplete or buggy code with `FIXME'
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- Other
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* calls to LOG() should always be all on one line (even past column 80)
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Class Relationships
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-------------------
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The doxygen documentation can help in understanding the relationships
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between objects. Use `make doxygen' in the top level directory to
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create the doxygen documentation into doc/doxygen/html. You must have
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doxygen installed, of course.
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FIXME -- high level overview of class relationships
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Portability
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-----------
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Synergy is mostly platform independent code but necessarily has
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platform dependent parts. The mundane platform dependent parts
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come from the usual suspects: networking, multithreading, file
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system, high resolution clocks, system logging, etc. Porting
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these parts is relatively straightforward.
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Synergy also has more esoteric platform dependent code. The
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functions for low-level event interception and insertion,
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warping the cursor position, character to keyboard event
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translation, clipboard manipulation, and screen saver control
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are often obscure and poorly documented. Unfortunately, these
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are exactly the functions synergy requires to do its magic.
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Porting synergy to a new platform requires the following steps:
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- Setting up the build
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- Adjusting lib/common/common.h
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- Implementing lib/arch
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- Implementing lib/platform
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- Tweaks
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Setting up the build:
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The first phase is simply to create the files necessary to build the
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other files. On Unix, synergy uses autoconf/automake which produces
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a `configure' script that generates makefiles. On Windows, synergy
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uses Visual C++ workspace and project files. If you're porting to
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another Unix variant, you may need to adjust `configure.in',
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`acinclude.m4', and Unix flavor dependent code in lib/arch. Note
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especially the SYSAPI_* and WINAPI_* macro definitions in
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ARCH_CFLAGS. Exactly one of each must be defined. It should also
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add AM_CONDITIONALs if a new SYSAPI_* or WINAPI_* was added.
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Adjusting lib/common/common.h:
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The lib/common/common.h header file is included directly or indirectly
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by every other file. Its primary job is to include config.h, which
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defines macros depending on what the 'configure' script discovered
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about the system. If the platform does not use the 'configure' script
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it must define the appropriate SYSAPI_* and WINAPI_* macro. It may
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also do other platform specific setup.
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Adjusting lib/common/BasicTypes.h:
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No changes should be necessary in BasicTypes.h. However, if the
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platform's system header files define SInt8, et al. you may need
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to adjust the typedefs to match the system's definitions.
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Implementing lib/arch:
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Much platform dependent code lives in lib/arch. There are several
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interface classes there and they must all be implemented for each
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platform. See the interface header files for more information.
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Platforms requiring special functions should create a class named
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CArchMiscXXX where XXX is the platform name. The class should have
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only static methods. Clients can include the appropriate header
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file and make calls directly, surrounded by a suitable #ifdef/#endif.
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If using automake, the Makefile.am should list the system specific
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files in a XXX_SOURCE_FILES macro where XXX matches the appropriate
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AM_CONDITIONAL symbol. XXX_SOURCE_FILES must be added to EXTRA_DIST
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and the following added above the INCLUDES macro:
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if XXX
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libarch_a_SOURCES = \
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$(COMMON_SOURCE_FILES) \
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$(XXX_SOURCE_FILES) \
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$(NULL)
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endif
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Implementing lib/platform:
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Most of the remaining platform dependent code lives in lib/platform.
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The code there implements platform dependent window, clipboard, keyboard
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and screen saver handling. If a platform is named XXX then the following
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classes should be derived and implemented:
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* CXXXClipboard : IClipboard
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Provides clipboard operations. Typically, this class will
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have helper classes for converting between various clipboard
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data formats.
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* CXXXEventQueueBuffer : IEventQueueBuffer
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Provides operations for waiting for, posting and retrieving events.
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Also provides operations for creating and deleting timers.
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* CXXXKeyState : CKeyState
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Provides operations for synthesizing key events and for mapping a
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key ID to a sequence of events to generate that key.
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* CXXXScreen : IScreen, IPrimaryScreen, ISecondaryScreen, IPlatformScreen
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Provides screen operations.
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* CXXXScreenSaver : IScreenSaver
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Provides screen saver operations.
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If using automake, the Makefile.am should list the window system
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specific files in a XXX_SOURCE_FILES macro where XXX matches the
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appropriate AM_CONDITIONAL symbol. XXX_SOURCE_FILES must be added
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to EXTRA_DIST and the following added above the INCLUDES macro:
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if XXX
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libplatform_a_SOURCES = $(XXX_SOURCE_FILES)
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endif
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Tweaks:
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Finally, each platform typically requires various adjustments here
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and there. In particular, synergyc.cpp and synergys.cpp usually
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require platform dependent code for the main entry point, parsing
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arguments, and reporting errors. Also, some platforms may benefit
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from a graphical user interface front end. These are generally
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not portable and synergy doesn't provide any infrastructure for
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the code common to any platform, though it may do so someday.
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There is, however, an implementation of a GUI front end for Windows
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that serves as an example.
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