Synergy Developer and Porting Guide =================================== This document is under development. Code Organization ----------------- The synergy source code organization is: . -- root makefiles, some standard documentation cmd -- program source code synergy -- synergy client synergyd -- synergy server config -- stuff for autoconf/automake dist -- files for creating distributions rpm -- files for creating RPMs doc -- placeholder for documentation examples -- example files lib -- library source code base -- simple utilities client -- synergy client library http -- simple http tools io -- I/O mt -- multithreading net -- networking platform -- platform dependent display/window/event stuff server -- synergy server library synergy -- synergy shared client/server code library Note how the utility code required by the programs is placed into separate library directories. This makes the makefiles a little more awkward but makes for a cleaner organization. The top level directory has only the standard documentation files and the files necessary to configure and build the rest of the project. Coding Style Guide ------------------ Synergy uses many coding conventions. Contributed code should following these guidelines. - Dependencies * No circular library dependencies Library dependencies form an acyclic graph. Conceptually libraries can be arranged in layers where each library only references libraries in layers below it, not in the same layer or layers above it. The makefiles build the lowest layer libraries first and work upwards. * Avoid circular uses-a relationships When possible, design classes with one-way uses-a relationships and avoid cycles. This makes it easier to understand the code. However, sometimes it's not always practical so it is permitted. - C++ * C++ features Synergy uses the following more recent C++ features: * bool * templates * exceptions * mutable * new scoping rules * the standard C++ library Do not use the following C++ features: * dynamic_cast * run time type information * namespaces and using (use std:: where necessary) The new scoping rules say that the scope of a variable declared in a for statement is limited to the for loop. For example: for (int i = 0; i < 10; ++i) { // i is in scope here } // i is not in scope here for (int i = -10; i < 0; ++i) { // an entirely new i is in scope here } // i is not in scope here This is used routinely in synergy, but only in for loops. There is a macro for `for' in lib/base/common.h when building under Microsoft Visual C++ that works around the fact that that compiler doesn't follow the new scoping rules. Use the macro if your compiler using the old scoping rules. * Standard C++ library The standard C++ library containers should always be used in favor of custom containers wherever reasonable. std::string is used throughout synergy but only as the CString typedef; always use CString, never std::string. Synergy avoids using auto_ptr due to some portability problems. Synergy makes limited use of standard algorithms and streams but they can be freely used in new code. * Limited multiple inheritance Classes should inherit implementation from at most one superclass. Inheriting implementation from multiple classes can have unpleasant consequences in C++ due to it's limited capabilities. Classes can inherit from any number of interface classes. An interface class provides only pure virtual methods. Synergy breaks this rule in two places. First is that IInterface implements the virtual destructor. However, it's just an empty method so it doesn't really count. Second is MXErrno which provides implementation for exceptions that use the global errno variable. * No globals Avoid global variables. All global variables must be static, making it visible only with its source file. Most uses of global variables are better served by static data members of a class. Global constants are permitted in some circumstances. Also avoid global functions. Use public static member functions in a class instead. These rules are violated by the main source file for each program (except that the globals are still static). They could easily be rewritten to put all the variables and functions into a class but there's little to be gained by that. * Private data only If a class is plain-old-data (i.e. it has no methods) all of its data members should be public. Otherwise all of its data members should be private, not public or protected. This makes it much easier to track the use of a member when reading code. Protected data is not allowed because `protected' is a synonym for `public to my subclasses' and public data is Bad Thing. While it might seem okay in this limited situation, the situation is not at all limited since an arbitrary number of classes can be derived, directly or indirectly, from the class and any of those classes have full access to the protected data. * Don't test for NULL when using `delete' or `delete[]' It's unnecessary since delete does it anyway. - Naming Names always begin with a letter (never an underscore). The first letter of interior names are always capitalized. Acronyms should be all uppercase. For example: myTextAsASCII. Names come it two flavors: leading capital and leading lowercase. The former have the first character capitalized and the latter don't. In the following table, leading capital names are indicated by `Name' and leading lowercase names by `name'. The naming convention for various things are: * Exceptions -- X + Name XMyException * Interfaces -- I + Name IMyInterface * Template Classes -- T + Name TMyTemplate<> * Other Classes -- C + Name CMyClass * Enumerations -- E + Name EMyEnumeration * Constants -- k + Name kMyConstant * Data Members -- m_ + name m_myDataMember * Methods -- name myMethod * Functions -- name myFunction * Variables -- name myVariable Exceptions are types that get thrown and are generally derived (possibly indirectly) from XBase. Interfaces are derived (possibly indirectly) from IInterface and have only pure virtual functions. Other classes are classes that aren't exceptions or interfaces. Constants include global constants and enumerants. - Formatting Every project has its own formatting style and no style satisfies everyone. New code should be consistent with existing code: * Use tabs to indent * Tabs are 4 columns * Open braces ({) go on same line as introducing statement `for (i = 0; i < 10; ++i) {' not for (i = 0; i < 10; ++i) { * Close braces line up with introducing statement * Open brace for function is on a line by itself in first column * Close brace for function lines up with open brace * Always use braces on: if, else, for, while, do, switch * `else {' goes on it's own line * Always explicitly test pointers against NULL e.g. `if (ptr == NULL)' not `if (ptr)' * Put spaces around binary operators and after statements e.g. `if (a == b) {' not `if(a==b){' * C'tor initializers are one per line, indented one tab stop * Other indentation should follow existing practice * Use Qt style comments for extraction by doxygen * Mark incomplete or buggy code with `FIXME' Class Relationships ------------------- The doxygen documentation can help in understanding the relationships between objects. Use `make doxygen' in the top level directory to create the doxygen documentation into doc/doxygen/html. You must have doxygen installed, of course. FIXME -- high level overview of class relationships Portability ----------- FIXME -- information about porting to new platforms