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*-cvs: asterisk/doc CODING-GUIDELINES,1.4,1.5

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Author: Matt Riddell
Daily Asterisk News
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The Coding guidelines for Asterisk have been updated to remind people not to create uninitialized variables among other things:

Make sure you never use an uninitialized variable. The compiler will usually warn you if you do so.

Name global variables (or local variables when you have a lot of them or are in a long function) something that will make sense to aliens who find your code in 100 years. All variable names should be in lower case.

Make some indication in the name of global variables which represent options that they are in fact intended to be global.
e.g.: static char global_something[80]

When making applications, always ast_strdupa(data) to a local pointer if you intend to parse it.
if(data)
mydata = ast_strdupa(data);

Always derefrence or localize pointers to things that are not yours like channel members in a channel that is not associated with the current thread and for which you do not have a lock.
channame = ast_strdupa(otherchan->name);

If you do the same or a similar operation more than 1 time, make it a function or macro.

Make sure you are not duplicating any functionality already found in an API call somewhere. If you are duplicating functionality found in another static function, consider the value of creating a new API call which can be shared.

When you achieve your desired functionalty, make another few refactor passes over the code to optimize it.

Before submitting a patch, *read* the actual patch file to be sure that all the changes you expect to be there are, and that there are no surprising changes you did not expect.

If you are asked to make changes to your patch, there is a good chance the changes will introduce bugs, check it even more at this stage.

Avoid needless malloc(),strdup() calls. If you only need the value in the scope of your function try ast_strdupa() or declare struts static and pass them as a pointer with &.

If you are going to reuse a computable value, save it in a variable instead of recomputing it over and over.

Just an Example:

if (strlen(name)) {
newname = alloca(strlen(name));
strncpy(newname, name, strlen(name);
}

vs

if((len = strlen(name))) {
newname = alloca(len);
strncpy(newname, name, len);
}

Use const on pointers which your function will not be modifying, as this allows the compiler to make certain optimizations.


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