| - Privoxy Developer Manual - | -||
|---|---|---|
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This set of standards is designed to make our lives easier. It is developed with the simple goal of helping us + keep the "new and improved Privoxy" consistent and reliable. Thus making + maintenance easier and increasing chances of success of the project.
+And that of course comes back to us as individuals. If we can increase our development and product + efficiencies then we can solve more of the request for changes/improvements and in general feel good about + ourselves. ;->
- This set of standards is designed to make our lives easier. It is - developed with the simple goal of helping us keep the "new and - improved Privoxy" consistent and - reliable. Thus making maintenance easier and increasing chances of - success of the project. -
-- And that of course comes back to us as individuals. If we can - increase our development and product efficiencies then we can solve - more of the request for changes/improvements and in general feel - good about ourselves. ;-> -
-- Explanation: -
-- Comment as much as possible without commenting the obvious. For - example do not comment "variable_a is equal to variable_b". - Instead explain why variable_a should be equal to the variable_b. - Just because a person can read code does not mean they will - understand why or what is being done. A reader may spend a lot - more time figuring out what is going on when a simple comment or - explanation would have prevented the extra research. Please help - your brother IJB'ers out! -
-- The comments will also help justify the intent of the code. If - the comment describes something different than what the code is - doing then maybe a programming error is occurring. -
-- Example: -
-
-
-/* if page size greater than 1k ... */
-if ( page_length() > 1024 )
-{
- ... "block" the page up ...
-}
-
-/* if page size is small, send it in blocks */
-if ( page_length() > 1024 )
-{
- ... "block" the page up ...
-}
-
-This demonstrates 2 cases of "what not to do". The first is a
-"syntax comment". The second is a comment that does not fit what
-is actually being done.
-
- |
-
- Explanation: -
-- Comments can help or they can clutter. They help when they are - differentiated from the code they describe. One line comments do - not offer effective separation between the comment and the code. - Block identifiers do, by surrounding the code with a clear, - definable pattern. -
-- Example: -
-
-
-/*********************************************************************
- * This will stand out clearly in your code!
- *********************************************************************/
-if ( this_variable == that_variable )
-{
- do_something_very_important();
-}
+ |
+
- Explanation: -
-- Use all lowercase, and separate words via an underscore ('_'). Do - not start an identifier with an underscore. (ANSI C reserves - these for use by the compiler and system headers.) Do not use - identifiers which are reserved in ANSI C++. (E.g. template, - class, true, false, ...). This is in case we ever decide to port - Privoxy to C++. -
-- Example: -
-
--int ms_iis5_hack = 0; -- |
-
- Instead of: -
-
--int msiis5hack = 0; int msIis5Hack = 0; -- |
-
- Explanation: -
-- Use all lowercase, and separate words via an underscore ('_'). Do - not start an identifier with an underscore. (ANSI C reserves - these for use by the compiler and system headers.) Do not use - identifiers which are reserved in ANSI C++. (E.g. template, - class, true, false, ...). This is in case we ever decide to port - Privoxy to C++. -
-- Example: -
-
--int load_some_file( struct client_state *csp ) -- |
-
- Instead of: -
-
--int loadsomefile( struct client_state *csp ) -int loadSomeFile( struct client_state *csp ) -- |
-
- Explanation: -
-- Use a descriptive parameter name in the function prototype in - header files. Use the same parameter name in the header file that - you use in the c file. -
-- Example: -
-
--(.h) extern int load_aclfile( struct client_state *csp ); -(.c) int load_aclfile( struct client_state *csp ) -- |
-
- Instead of: -
-
--(.h) extern int load_aclfile( struct client_state * ); or -(.h) extern int load_aclfile(); -(.c) int load_aclfile( struct client_state *csp ) -- |
-
- Explanation: -
-- Use all capital letters, with underscores between words. Do not - start an identifier with an underscore. (ANSI C reserves these - for use by the compiler and system headers.) -
-- Example: -
-
-
-(enumeration) : enum Boolean { FALSE, TRUE };
-(#define) : #define DEFAULT_SIZE 100;
-
- |
-
- Note: We - have a standard naming scheme for #defines that toggle a feature - in the preprocessor: FEATURE_>, where > is a short - (preferably 1 or 2 word) description. -
-- Example: -
-
--#define FEATURE_FORCE 1 - -#ifdef FEATURE_FORCE -#define FORCE_PREFIX blah -#endif /* def FEATURE_FORCE */ -- |
-
- Explanation: -
-- Spell common words out entirely (do not remove vowels). -
-- Use only widely-known domain acronyms and abbreviations. - Capitalize all letters of an acronym. -
-- Use underscore (_) to separate adjacent acronyms and - abbreviations. Never terminate a name with an underscore. -
-- Example: -
-
--#define USE_IMAGE_LIST 1 -- |
-
- Instead of: -
-
--#define USE_IMG_LST 1 or -#define _USE_IMAGE_LIST 1 or -#define USE_IMAGE_LIST_ 1 or -#define use_image_list 1 or -#define UseImageList 1 -- |
-
Explanation:
+Logical steps should be commented to help others follow the intent of the written code and comments will + make the code more readable.
+If you have 25 lines of code without a comment, you should probably go back into it to see where you forgot + to put one.
+Most "for", "while", "do", etc... loops _probably_ need a comment. After all, these are usually major logic + containers.
- Explanation: -
-- The brace needs to be on a line all by itself, not at the end of - the statement. Curly braces should line up with the construct - that they're associated with. This practice makes it easier to - identify the opening and closing braces for a block. -
-- Example: -
-
-
-if ( this == that )
-{
- ...
-}
-
- |
-
- Instead of: -
-- if ( this == that ) { ... } -
-- or -
-- if ( this == that ) { ... } -
-- Note: In - the special case that the if-statement is inside a loop, and it - is trivial, i.e. it tests for a condition that is obvious from - the purpose of the block, one-liners as above may optically - preserve the loop structure and make it easier to read. -
-- Status: - developer-discretion. -
-- Example - exception: -
-
-
-while ( more lines are read )
-{
- /* Please document what is/is not a comment line here */
- if ( it's a comment ) continue;
-
- do_something( line );
-}
-
- |
-
- Explanation: -
-- Using braces to make a block will make your code more readable - and less prone to error. All control statements should have a - block defined. -
-- Example: -
-
-
-if ( this == that )
-{
- do_something();
- do_something_else();
-}
-
- |
-
- Instead of: -
-- if ( this == that ) do_something(); do_something_else(); -
-- or -
-- if ( this == that ) do_something(); -
-- Note: The - first example in "Instead of" will execute in a manner other than - that which the developer desired (per indentation). Using code - braces would have prevented this "feature". The "explanation" and - "exception" from the point above also applies. -
-- Example: -
-
--structure->flag = ( condition ); -- |
-
- Instead of: -
-- if ( condition ) { structure->flag = 1; } else { - structure->flag = 0; } -
-- Note: The - former is readable and concise. The later is wordy and - inefficient. Please assume that any developer new to the project - has at least a "good" knowledge of C/C++. (Hope I do not offend - by that last comment ... 8-) -
-- Explanation: -
-- Make it readable. The notable exception to using white space - freely is listed in the next guideline. -
-- Example: -
-
--int first_value = 0; -int some_value = 0; -int another_value = 0; -int this_variable = 0; - -if ( this_variable == this_variable ) - -first_value = old_value + ( ( some_value - another_value ) - whatever ) -- |
-
- Explanation: -
-- - structure pointer operator ( "->" ) - member operator ( "." - ) - functions and parentheses -
-- It is a general coding practice to put pointers, references, and - function parentheses next to names. With spaces, the connection - between the object and variable/function name is not as clear. -
-- Example: -
-
--a_struct->a_member; -a_struct.a_member; -function_name(); -- |
-
- Instead of: - a_struct -> a_member; a_struct . a_member; function_name (); -
-- Example: -
-
-
-int function1( ... )
-{
- ...code...
- return( ret_code );
-
-} /* -END- function1 */
-
-
-int function2( ... )
-{
-} /* -END- function2 */
-
- |
-
- Instead of: -
-- int function1( ... ) { ...code... return( ret_code ); } int - function2( ... ) { } -
-- Note: Use 1 - blank line before the closing brace and 2 lines afterward. This - makes the end of function standout to the most casual viewer. - Although function comments help separate functions, this is still - a good coding practice. In fact, I follow these rules when using - blocks in "for", "while", "do" loops, and long if {} statements - too. After all whitespace is free! -
-- Status: - developer-discretion on the number of blank lines. Enforced is - the end of function comments. -
-- Explanation: -
-- If some use 8 character TABs and some use 3 character TABs, the - code can look *very* ragged. So use 3 character indentions only. - If you like to use TABs, pass your code through a filter such as - "expand -t3" before checking in your code. -
-- Example: -
-
-
-static const char * const url_code_map[256] =
-{
- NULL, ...
-};
-
-
-int function1( ... )
-{
- if ( 1 )
- {
- return( ALWAYS_TRUE );
- }
- else
- {
- return( HOW_DID_YOU_GET_HERE );
- }
+
+ |
+
- Explanation: -
-- Do not assume that the variables declared will not be used until - after they have been assigned a value somewhere else in the code. - Remove the chance of accidentally using an unassigned variable. -
-- Example: -
-
--short a_short = 0; -float a_float = 0; -struct *ptr = NULL; -- |
-
- Note: It is - much easier to debug a SIGSEGV if the message says you are trying - to access memory address 00000000 and not 129FA012; or - array_ptr[20] causes a SIGSEV vs. array_ptr[0]. -
-- Status: - developer-discretion if and only if the variable is assigned a - value "shortly after" declaration. -
-Explanation:
+Use all lowercase, and separate words via an underscore ('_'). Do not start an identifier with an + underscore. (ANSI C reserves these for use by the compiler and system headers.) Do not use identifiers which + are reserved in ANSI C++. (E.g. template, class, true, false, ...). This is in case we ever decide to port + Privoxy to C++.
+Example:
+
+ int ms_iis5_hack = 0;+ |
+
Instead of:
+
+ int msiis5hack = 0; int msIis5Hack = 0;+ |
+
- Explanation: -
-- Value should be phrased as a question that would logically be - answered as a true or false statement -
-- Example: -
-
--should_we_block_this(); -contains_an_image(); -is_web_page_blank(); -- |
-
- Explanation: -
-- The default return for a function is an int. To avoid ambiguity, - create a return for a function when the return has a purpose, and - create a void return type if the function does not need to return - anything. -
-- Explanation: -
-- It is easy to write the following code, and a clear argument can - be made that the code is easy to understand: -
-- Example: -
-
-
-for ( size_t cnt = 0; cnt < block_list_length(); cnt++ )
-{
- ....
-}
-
- |
-
- Note: - Unfortunately, this makes a function call for each and every - iteration. This increases the overhead in the program, because - the compiler has to look up the function each time, call it, and - return a value. Depending on what occurs in the - block_list_length() call, it might even be creating and - destroying structures with each iteration, even though in each - case it is comparing "cnt" to the same value, over and over. - Remember too - even a call to block_list_length() is a function - call, with the same overhead. -
-- Instead of using a function call during the iterations, assign - the value to a variable, and evaluate using the variable. -
-- Example: -
-
-
-size_t len = block_list_length();
-
-for ( size_t cnt = 0; cnt < len; cnt++ )
-{
- ....
-}
-
- |
-
- Exceptions: - if the value of block_list_length() *may* change or could - *potentially* change, then you must code the function call in the - for/while loop. -
-- Explanation: -
-- This allows a developer to define a const pointer and call your - function. If your function does not have the const keyword, we - may not be able to use your function. Consider strcmp, if it were - defined as: extern int strcmp( char *s1, char *s2 ); -
-- I could then not use it to compare argv's in main: int main( int - argc, const char *argv[] ) { strcmp( argv[0], "privoxy" ); } -
-- Both these pointers are *const*! If the c runtime library - maintainers do it, we should too. -
-- Explanation: -
-- Most structures cannot fit onto a normal stack entry (i.e. they - are not 4 bytes or less). Aka, a function declaration like: int - load_aclfile( struct client_state csp ) -
-- would not work. So, to be consistent, we should declare all - prototypes with "pass by value": int load_aclfile( struct - client_state *csp ) -
-- Explanation: -
-- Your include statements should contain the file name without a - path. The path should be listed in the Makefile, using -I as - processor directive to search the indicated paths. An exception - to this would be for some proprietary software that utilizes a - partial path to distinguish their header files from system or - other header files. -
-- Example: -
-
--#include <iostream.h> /* This is not a local include */ -#include "config.h" /* This IS a local include */ -- |
-
- Exception: -
-
--/* This is not a local include, but requires a path element. */ -#include <sys/fileName.h> -- |
-
- Note: - Please! do not add "-I." to the Makefile without a _very_ good - reason. This duplicates the #include "file.h" behavior. -
-- Explanation: -
-- Prevents compiler and linker errors resulting from redefinition - of items. -
-- Wrap each header file with the following syntax to prevent - multiple inclusions of the file. Of course, replace PROJECT_H - with your file name, with "." Changed to "_", and make it - uppercase. -
-- Example: -
-
--#ifndef PROJECT_H_INCLUDED -#define PROJECT_H_INCLUDED - ... -#endif /* ndef PROJECT_H_INCLUDED */ -- |
-
- Explanation: -
-- If our headers are included from C++, they must declare our - functions as `extern "C"`. This has no cost in C, but increases - the potential re-usability of our code. -
-- Example: -
-
-
-#ifdef __cplusplus
-extern "C"
-{
-#endif /* def __cplusplus */
-
-... function definitions here ...
-
-#ifdef __cplusplus
-}
-#endif /* def __cplusplus */
-
- |
-
- Explanation: -
-- Useful in headers that include pointers to other struct's. - Modifications to excess header files may cause needless compiles. -
-- Example: -
-
--/********************************************************************* - * We're avoiding an include statement here! - *********************************************************************/ -struct file_list; -extern file_list *xyz; -- |
-
- Note: If - you declare "file_list xyz;" (without the pointer), then - including the proper header file is necessary. If you only want - to prototype a pointer, however, the header file is unnecessary. -
-- Status: Use - with discretion. -
-Explanation:
+Use all lowercase, and separate words via an underscore ('_'). Do not start an identifier with an + underscore. (ANSI C reserves these for use by the compiler and system headers.) Do not use identifiers which + are reserved in ANSI C++. (E.g. template, class, true, false, ...). This is in case we ever decide to port + Privoxy to C++.
+Example:
+
+ int load_some_file(struct client_state *csp)+ |
+
Instead of:
+
+ int loadsomefile(struct client_state *csp) + int loadSomeFile(struct client_state *csp)+ |
+
- Explanation -
-- Compiler warnings are meant to help you find bugs. You should - turn on as many as possible. With GCC, the switch is "-Wall". Try - and fix as many warnings as possible. -
-- Explanation: -
-- What you think is guaranteed is never really guaranteed. The - value that you don't think you need to check is the one that - someday will be passed. So, to protect yourself from the unknown, - always have a default step in a switch statement. -
-- Example: -
-
-
-switch( hash_string( cmd ) )
-{
- case hash_actions_file :
- ... code ...
- break;
-
- case hash_confdir :
- ... code ...
- break;
-
- default :
- log_error( ... );
- ... anomaly code goes here ...
- continue; / break; / exit( 1 ); / etc ...
+
+ |
+
Explanation:
+Spell common words out entirely (do not remove vowels).
+Use only widely-known domain acronyms and abbreviations. Capitalize all letters of an acronym.
+Use underscore (_) to separate adjacent acronyms and abbreviations. Never terminate a name with an + underscore.
+Example:
+
+ #define USE_IMAGE_LIST 1+ |
+
Instead of:
+
+ #define USE_IMG_LST 1 or + #define _USE_IMAGE_LIST 1 or + #define USE_IMAGE_LIST_ 1 or + #define use_image_list 1 or + #define UseImageList 1+ |
+
- Example for file - comments: -
+Explanation:
+The brace needs to be on a line all by itself, not at the end of the statement. Curly braces should line up + with the construct that they're associated with. This practice makes it easier to identify the opening and + closing braces for a block.
+Example:
-
-const char FILENAME_rcs[] = "$Id: coding.html,v 1.54 2010/11/13 12:50:18 fabiankeil Exp $";
-/*********************************************************************
- *
- * File : $Source: /cvsroot/ijbswa/current/doc/webserver/developer-manual/coding.html,v $
- *
- * Purpose : (Fill me in with a good description!)
- *
- * Copyright : Written by and Copyright (C) 2001-2009
- * the Privoxy team. http://www.privoxy.org/
- *
- * This program is free software; you can redistribute it
- * and/or modify it under the terms of the GNU General
- * Public License as published by the Free Software
- * Foundation; either version 2 of the License, or (at
- * your option) any later version.
- *
- * This program is distributed in the hope that it will
- * be useful, but WITHOUT ANY WARRANTY; without even the
- * implied warranty of MERCHANTABILITY or FITNESS FOR A
- * PARTICULAR PURPOSE. See the GNU General Public
- * License for more details.
- *
- * The GNU General Public License should be included with
- * this file. If not, you can view it at
- * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
- * or write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 ,
- * USA
- *
- *********************************************************************/
+ |
+
Instead of:
+if (this == that) { ... }
+or
+if (this == that) { ... }
+Note: In the special case that the if-statement is + inside a loop, and it is trivial, i.e. it tests for a condition that is obvious from the purpose of the block, + one-liners as above may optically preserve the loop structure and make it easier to read.
+Status: developer-discretion.
+Example exception:
+
+ while (more lines are read)
+ {
+ /* Please document what is/is not a comment line here */
+ if (it's a comment) continue;
+ do_something(line);
+ }
+ |
+
Explanation:
+Using braces to make a block will make your code more readable and less prone to error. All control + statements should have a block defined.
+Example:
+
+ if (this == that)
+ {
+ do_something();
+ do_something_else();
+ }
+ |
+
Instead of:
+if (this == that) do_something(); do_something_else();
+or
+if (this == that) do_something();
+Note: The first example in "Instead of" will execute + in a manner other than that which the developer desired (per indentation). Using code braces would have + prevented this "feature". The "explanation" and "exception" from the point above also applies.
+Example:
+
+ structure->flag = (condition);+ |
+
Instead of:
+if (condition) { structure->flag = 1; } else { structure->flag = 0; }
+Note: The former is readable and concise. The later is + wordy and inefficient. Please assume that any developer new to the project has at least a "good" knowledge of + C/C++. (Hope I do not offend by that last comment ... 8-)
+Explanation:
+Make it readable. The notable exception to using white space freely is listed in the next guideline.
+Example:
+
+ int first_value = 0; + int some_value = 0; + int another_value = 0; + int this_variable = 0;+ |
+
Explanation:
+- structure pointer operator ( "->" ) - member operator ( "." ) - functions and parentheses
+It is a general coding practice to put pointers, references, and function parentheses next to names. With + spaces, the connection between the object and variable/function name is not as clear.
+Example:
+
+ a_struct->a_member; + a_struct.a_member; + function_name();+ |
+
Instead of: a_struct -> a_member; a_struct . + a_member; function_name ();
+Example:
+
+ int function1( ... )
+ {
+ ...code...
+ return(ret_code);
-#include "config.h"
+ } /* -END- function1 */
- ...necessary include files for us to do our work...
-const char FILENAME_h_rcs[] = FILENAME_H_VERSION;
-
+ int function2( ... )
+ {
+ } /* -END- function2 */
|
- Note: This - declares the rcs variables that should be added to the - "show-proxy-args" page. If this is a brand new creation by you, you - are free to change the "Copyright" section to represent the rights - you wish to maintain. -
-- Note: The - formfeed character that is present right after the comment flower - box is handy for (X|GNU)Emacs users to skip the verbiage and get to - the heart of the code (via `forward-page' and `backward-page'). - Please include it if you can. -
-- Example for file header - comments: -
+Instead of:
+int function1( ... ) { ...code... return(ret_code); } int function2( ... ) { }
+Note: Use 1 blank line before the closing brace and 2 + lines afterward. This makes the end of function standout to the most casual viewer. Although function comments + help separate functions, this is still a good coding practice. In fact, I follow these rules when using blocks + in "for", "while", "do" loops, and long if {} statements too. After all whitespace is free!
+Status: developer-discretion on the number of blank + lines. Enforced is the end of function comments.
+Explanation:
+If some use 8 character TABs and some use 3 character TABs, the code can look *very* ragged. So use 3 + character indentions only. If you like to use TABs, pass your code through a filter such as "expand -t3" before + checking in your code.
+Example:
-
-#ifndef _FILENAME_H
-#define _FILENAME_H
-#define FILENAME_H_VERSION "$Id: coding.html,v 1.54 2010/11/13 12:50:18 fabiankeil Exp $"
-/*********************************************************************
- *
- * File : $Source: /cvsroot/ijbswa/current/doc/webserver/developer-manual/coding.html,v $
- *
- * Purpose : (Fill me in with a good description!)
- *
- * Copyright : Written by and Copyright (C) 2001-2009
- * the Privoxy team. http://www.privoxy.org/
- *
- * This program is free software; you can redistribute it
- * and/or modify it under the terms of the GNU General
- * Public License as published by the Free Software
- * Foundation; either version 2 of the License, or (at
- * your option) any later version.
- *
- * This program is distributed in the hope that it will
- * be useful, but WITHOUT ANY WARRANTY; without even the
- * implied warranty of MERCHANTABILITY or FITNESS FOR A
- * PARTICULAR PURPOSE. See the GNU General Public
- * License for more details.
- *
- * The GNU General Public License should be included with
- * this file. If not, you can view it at
- * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
- * or write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 ,
- * USA
- *
- *********************************************************************/
+ |
+
Explanation:
+Do not assume that the variables declared will not be used until after they have been assigned a value + somewhere else in the code. Remove the chance of accidentally using an unassigned variable.
+Example:
+
+ short a_short = 0; + float a_float = 0; + struct *ptr = NULL;+ |
+
Note: It is much easier to debug a SIGSEGV if the + message says you are trying to access memory address 00000000 and not 129FA012; or array_ptr[20] causes a + SIGSEV vs. array_ptr[0].
+Status: developer-discretion if and only if the + variable is assigned a value "shortly after" declaration.
+Explanation:
+Value should be phrased as a question that would logically be answered as a true or false statement
+Example:
+
+ should_we_block_this(); + contains_an_image(); + is_web_page_blank();+ |
+
Explanation:
+The default return for a function is an int. To avoid ambiguity, create a return for a function when the + return has a purpose, and create a void return type if the function does not need to return anything.
+Explanation:
+It is easy to write the following code, and a clear argument can be made that the code is easy to + understand:
+Example:
+
+ for (size_t cnt = 0; cnt < block_list_length(); cnt++)
+ {
+ ....
+ }
+ |
+
Note: Unfortunately, this makes a function call for + each and every iteration. This increases the overhead in the program, because the compiler has to look up the + function each time, call it, and return a value. Depending on what occurs in the block_list_length() call, it + might even be creating and destroying structures with each iteration, even though in each case it is comparing + "cnt" to the same value, over and over. Remember too - even a call to block_list_length() is a function call, + with the same overhead.
+Instead of using a function call during the iterations, assign the value to a variable, and evaluate using + the variable.
+Example:
+
+ size_t len = block_list_length();
+ for (size_t cnt = 0; cnt < len; cnt++)
+ {
+ ....
+ }
+ |
+
Exceptions: if the value of block_list_length() *may* + change or could *potentially* change, then you must code the function call in the for/while loop.
+Explanation:
+This allows a developer to define a const pointer and call your function. If your function does not have the + const keyword, we may not be able to use your function. Consider strcmp, if it were defined as: extern int + strcmp(char *s1, char *s2);
+I could then not use it to compare argv's in main: int main(int argc, const char *argv[]) { strcmp(argv[0], + "privoxy"); }
+Both these pointers are *const*! If the c runtime library maintainers do it, we should too.
+Explanation:
+Most structures cannot fit onto a normal stack entry (i.e. they are not 4 bytes or less). Aka, a function + declaration like: int load_aclfile(struct client_state csp)
+would not work. So, to be consistent, we should declare all prototypes with "pass by value": int + load_aclfile(struct client_state *csp)
+Explanation:
+Your include statements should contain the file name without a path. The path should be listed in the + Makefile, using -I as processor directive to search the indicated paths. An exception to this would be for some + proprietary software that utilizes a partial path to distinguish their header files from system or other header + files.
+Example:
+
+ #include <iostream.h> /* This is not a local include */ + #include "config.h" /* This IS a local include */+ |
+
Exception:
+
+ /* This is not a local include, but requires a path element. */ + #include <sys/fileName.h>+ |
+
Note: Please! do not add "-I." to the Makefile without + a _very_ good reason. This duplicates the #include "file.h" behavior.
+Explanation:
+Prevents compiler and linker errors resulting from redefinition of items.
+Wrap each header file with the following syntax to prevent multiple inclusions of the file. Of course, + replace PROJECT_H with your file name, with "." Changed to "_", and make it uppercase.
+Example:
+
+ #ifndef PROJECT_H_INCLUDED + #define PROJECT_H_INCLUDED + ... + #endif /* ndef PROJECT_H_INCLUDED */+ |
+
Explanation:
+If our headers are included from C++, they must declare our functions as `extern "C"`. This has no cost in + C, but increases the potential re-usability of our code.
+Example:
+
+ #ifdef __cplusplus
+ extern "C"
+ {
+ #endif /* def __cplusplus */
-/* Revision control strings from this header and associated .c file */
-extern const char FILENAME_rcs[];
-extern const char FILENAME_h_rcs[];
+ ... function definitions here ...
+ #ifdef __cplusplus
+ }
+ #endif /* def __cplusplus */
+ |
+
Explanation:
+Useful in headers that include pointers to other struct's. Modifications to excess header files may cause + needless compiles.
+Example:
+
+ /********************************************************************* + * We're avoiding an include statement here! + *********************************************************************/ + struct file_list; + extern file_list *xyz;+ |
+
Note: If you declare "file_list xyz;" (without the + pointer), then including the proper header file is necessary. If you only want to prototype a pointer, however, + the header file is unnecessary.
+Status: Use with discretion.
+Explanation
+Compiler warnings are meant to help you find bugs. You should turn on as many as possible. With GCC, the + switch is "-Wall". Try and fix as many warnings as possible.
+Explanation:
+What you think is guaranteed is never really guaranteed. The value that you don't think you need to check is + the one that someday will be passed. So, to protect yourself from the unknown, always have a default step in a + switch statement.
+Example:
+
+ switch (hash_string(cmd))
+ {
+ case hash_actions_file:
+ ... code ...
+ break;
-#ifdef __cplusplus
-} /* extern "C" */
-#endif
+ case hash_confdir:
+ ... code ...
+ break;
-#endif /* ndef _FILENAME_H */
+ default:
+ log_error( ... );
+ ... anomaly code goes here ...
+ continue; / break; / exit( 1 ); / etc ...
-/*
- Local Variables:
- tab-width: 3
- end:
-*/
-
+ } /* end switch (hash_string(cmd)) */
|
- Example for function - comments: -
+Note: If you already have a default condition, you are + obviously exempt from this point. Of note, most of the WIN32 code calls `DefWindowProc' after the switch + statement. This API call *should* be included in a default statement.
+Another Note: This is not so much a readability issue + as a robust programming issue. The "anomaly code goes here" may be no more than a print to the STDERR stream + (as in load_config). Or it may really be an abort condition.
+Status: Programmer discretion is advised.
+Explanation:
+In general, you will want to have a 'break' statement within each 'case' of a switch statement. This allows + for the code to be more readable and understandable, and furthermore can prevent unwanted surprises if someone + else later gets creative and moves the code around.
+The language allows you to plan the fall through from one case statement to another simply by omitting the + break statement within the case statement. This feature does have benefits, but should only be used in rare + cases. In general, use a break statement for each case statement.
+If you choose to allow fall through, you should comment both the fact of the fall through and reason why you + felt it was necessary.
+Explanation:
+The type of size_t varies across platforms. Do not make assumptions about whether it is signed or unsigned, + or about how long it is. Do not compare a size_t against another variable of a different type (or even against + a constant) without casting one of the values.
+Explanation:
+It can be tempting to declare a series of variables all on one line. Don't.
+Example:
-
-/*********************************************************************
- *
- * Function : FUNCTION_NAME
- *
- * Description : (Fill me in with a good description!)
- *
- * parameters :
- * 1 : param1 = pointer to an important thing
- * 2 : x = pointer to something else
- *
- * Returns : 0 => Ok, everything else is an error.
- *
- *********************************************************************/
-int FUNCTION_NAME( void *param1, const char *x )
-{
- ...
- return( 0 );
-
-}
-
+ long a = 0; + long b = 0; + long c = 0;+ |
+
Instead of:
+long a, b, c;
+Explanation: - there is more room for comments on the + individual variables - easier to add new variables without messing up the original ones - when searching on a + variable to find its type, there is less clutter to "visually" eliminate
+Exceptions: when you want to declare a bunch of loop + variables or other trivial variables; feel free to declare them on one line. You should, although, provide a + good comment on their functions.
+Status: developer-discretion.
+Explanation:
+Create a local struct (on the stack) if the variable will live and die within the context of one function + call.
+Only "malloc" a struct (on the heap) if the variable's life will extend beyond the context of one function + call.
+Example:
+
+ If a function creates a struct and stores a pointer to it in a + list, then it should definitely be allocated via `malloc'.+ |
+
Explanation:
+If you have to "malloc" an instance, you are responsible for insuring that the instance is `free'd, even if + the deallocation event falls within some other programmer's code. You are also responsible for ensuring that + deletion is timely (i.e. not too soon, not too late). This is known as "low-coupling" and is a "good thing + (tm)". You may need to offer a free/unload/destructor type function to accommodate this.
+Example:
+
+ int load_re_filterfile(struct client_state *csp) { ... }
+ static void unload_re_filterfile(void *f) { ... }
|
- Note: If we - all follow this practice, we should be able to parse our code to - create a "self-documenting" web page. -
+Exceptions:
+The developer cannot be expected to provide `free'ing functions for C run-time library functions ... such as + `strdup'.
+Status: developer-discretion. The "main" use of this + standard is for allocating and freeing data structures (complex or nested).
+Explanation:
+I have ordered all of the "blocker" file code to be in alpha order. It is easier to add/read new blockers + when you expect a certain order.
+Note: It may appear that the alpha order is broken in + places by POPUP tests coming before PCRS tests. But since POPUPs can also be referred to as KILLPOPUPs, it is + clear that it should come first.
+Explanation:
+If you have enough confidence in new code or confidence in your changes, but are not *quite* sure of the + repercussions, add this:
+/* XXX: this code has a logic error on platform XYZ, * attempting to fix */ #ifdef PLATFORM ...changed code + here... #endif
+or:
+/* XXX: I think the original author really meant this... */ ...changed code here...
+or:
+/* XXX: new code that *may* break something else... */ ...new code here...
+Note: If you make it clear that this may or may not be + a "good thing (tm)", it will be easier to identify and include in the project (or conversely exclude from the + project).
| - Prev - | -- Home - | -- Next + |
+ /********************************************************************* + * + * File : $Source + * + * Purpose : (Fill me in with a good description!) + * + * Copyright : Written by and Copyright (C) 2001-2009 + * the Privoxy team. https://www.privoxy.org/ + * + * This program is free software; you can redistribute it + * and/or modify it under the terms of the GNU General + * Public License as published by the Free Software + * Foundation; either version 2 of the License, or (at + * your option) any later version. + * + * This program is distributed in the hope that it will + * be useful, but WITHOUT ANY WARRANTY; without even the + * implied warranty of MERCHANTABILITY or FITNESS FOR A + * PARTICULAR PURPOSE. See the GNU General Public + * License for more details. + * + * The GNU General Public License should be included with + * this file. If not, you can view it at + * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html + * or write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 , + * USA + * + *********************************************************************/ + + + #include "config.h" + + ...necessary include files for us to do our work... + + const char FILENAME_h_rcs[] = FILENAME_H_VERSION; |
Note: This declares the rcs variables that should be + added to the "show-version" page. If this is a brand new creation by you, you are free to change the "Copyright" + section to represent the rights you wish to maintain.
+Note: The formfeed character that is present right after + the comment flower box is handy for (X|GNU)Emacs users to skip the verbiage and get to the heart of the code (via + `forward-page' and `backward-page'). Please include it if you can.
+Example for file header comments:
+| - Documentation Guidelines - | -- + |
+ #ifndef _FILENAME_H
+ #define _FILENAME_H
+ /*********************************************************************
+ *
+ * File : $Source
+ *
+ * Purpose : (Fill me in with a good description!)
+ *
+ * Copyright : Written by and Copyright (C) 2001-2009
+ * the Privoxy team. https://www.privoxy.org/
+ *
+ * This program is free software; you can redistribute it
+ * and/or modify it under the terms of the GNU General
+ * Public License as published by the Free Software
+ * Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will
+ * be useful, but WITHOUT ANY WARRANTY; without even the
+ * implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE. See the GNU General Public
+ * License for more details.
+ *
+ * The GNU General Public License should be included with
+ * this file. If not, you can view it at
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 ,
+ * USA
+ *
+ *********************************************************************/
+
+
+ #include "project.h"
+
+ #ifdef __cplusplus
+ extern "C" {
+ #endif
+
+ ... function headers here ...
+
+
+ /* Revision control strings from this header and associated .c file */
+ extern const char FILENAME_rcs[];
+ extern const char FILENAME_h_rcs[];
+
+
+ #ifdef __cplusplus
+ } /* extern "C" */
+ #endif
+
+ #endif /* ndef _FILENAME_H */
+
+ /*
+ Local Variables:
+ tab-width: 3
+ end:
+ */
|
- - Testing Guidelines + |
Example for function comments:
+
+ /*********************************************************************
+ *
+ * Function : FUNCTION_NAME
+ *
+ * Description : (Fill me in with a good description!)
+ *
+ * parameters :
+ * 1 : param1 = pointer to an important thing
+ * 2 : x = pointer to something else
+ *
+ * Returns : 0 => Ok, everything else is an error.
+ *
+ *********************************************************************/
+ int FUNCTION_NAME(void *param1, const char *x)
+ {
+ ...
+ return 0;
+
+ }
|
Note: If we all follow this practice, we should be able + to parse our code to create a "self-documenting" web page.