uGFX coding style This is a short document describing the preferred coding style for uGFX. Chapter 1: Indentation Tabs are 4 characters, and thus indentations are also 4 characters. Rationale: We like 4 character tabs much better than 8 character tabs. It is more readable. Chapter 2: Placing Braces The preferred way, as shown to us by the prophets Kernighan and Ritchie, is to put the opening brace last on the line, and put the closing brace first, thusly: if (x is true) { we do y } However, there is one special case, namely functions: they have the opening brace at the beginning of the next line, thus: int function(int x) { body of function } We will however accept braces in the general block style for functions but not the other way around. General blocks MUST have their opening brace on the same line as the conditional statement. Note that the closing brace is empty on a line of its own, _except_ in the cases where it is followed by a continuation of the same statement, ie a "while" in a do-statement or an "else" in an if-statement, like this: do { body of do-loop } while (condition); and if (x == y) { .. } else if (x > y) { ... } else { .... } Note that closing brace is indented to the level of the start of the block. Structure definitions are an optional exception. Both of the below style are acceptable: typedef struct { int a; ... } mytype; struct mystruct { int a; ... } Chapter 3: Naming C is a Spartan language, and so should your naming be. Unlike Modula-2 and Pascal programmers, C programmers do not use cute names like ThisVariableIsATemporaryCounter. A C programmer would call that variable "tmp", which is much easier to write, and a lot less difficult to understand. HOWEVER, while long mixed-case names are frowned upon, descriptive names for global variables are a must. To call a global function "foo" is a shooting offense. GLOBAL variables (to be used only if you _really_ need them) need to have descriptive names, as do global functions. If you have a function that counts the number of active users, you should call that "countActiveUsers()" or similar, you should _not_ call it "cntusr()". WHERE long names are required as described above, we prefer the use of capitalisation on subsequent words (but not the first) rather than underscores to seperate the words. For example "countActiveUsers()" is preferred to "count_active_users()" as it is at least as readable and is shorter. Encoding the type of a function into the name (so-called Hungarian notation) is brain damaged - the compiler knows the types anyway and can check those, and it only confuses the programmer. LOCAL variable names should be short, and to the point. If you have some random integer loop counter, it should probably be called "i". Calling it "loopCounter" is non-productive, if there is no chance of it being mis-understood. Similarly, "tmp" can be just about any type of variable that is used to hold a temporary value. Chapter 4: Functions Functions should be short and sweet, and do just one thing. The maximum length of a function is inversely proportional to the complexity and indentation level of that function. So, if you have a conceptually simple function that is just one long (but simple) case-statement, where you have to do lots of small things for a lot of different cases, it's OK to have a longer function. However, if you have a complex function, and you suspect that a less-than-gifted first-year high-school student might not even understand what the function is all about, you should adhere to the maximum limits all the more closely. Use helper functions with descriptive names (you can ask the compiler to in-line them if you think it's performance-critical, and it will probably do a better job of it that you would have done). Another measure of the function is the number of local variables. They shouldn't exceed 5-10, or you're possibly doing something wrong. Re-think the function, and split it into smaller pieces. A human brain can generally easily keep track of about 7 different things, anything more and it gets confused. You need to understand what you did 2 weeks from now. Because uGFX is intended for embedded platforms there are other considerations that may cause exceptions or emphasise the above. For example, stack space is a premium. This means that the number of local variables should be minimised as should the number of parameters. Passing through multiple levels of functions with lots of parameters is very bad indeed and this can override the desire to keep functions short and sweet. Clarity however is still essential. Chapter 5: Commenting Comments are good, but there is also a danger of over-commenting. NEVER try to explain HOW your code works in a comment: it's much better to write the code so that the _working_ is obvious, and it's a waste of time to explain badly written code. Generally, you want your comments to tell WHAT your code does, not HOW. We use doxygen to document the system. That means that most public functions are documented in the header defintion file. We do not put doxygen comments in the source file itself. Within the source file, comments should be used to seperate blocks of functions or definitions within the file. This is to provide clarity to the structure of the source file itself. An example could be: /*************************** * Drawing Functions ***************************/ Single line comments using "//" to start the comment should be used for just that purpose, to assist in the understanding of that single line. Mutliple single line comments should never be used to create a block comment. For example, // This is a very long // comment spanning several // lines is a very bad use of comments. Comments within function bodies should be small comments to note or warn about something particularly clever (or ugly), but try to avoid excess. Instead, put the comments at the head of a block of code to explain the block rather than a comment on each line.