| 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.
- +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 fellow Privoxy developers 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 )
+
|
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.
- +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:
-
-
-/*********************************************************************
+
|
Exception:
- -If you are trying to add a small logic comment and do not wish to - "disrupt" the flow of the code, feel free to use a 1 line comment - which is NOT on the same line as the code.
+Exception:
+If you are trying to add a small logic comment and do not wish to "disrupt" the flow of the code, feel free + to use a 1 line comment which is NOT on the same line as the code.
Explanation:
- -It goes back to the question of readability. If the comment is on - the same line as the code it will be harder to read than the comment - that is on its own line.
- -There are three exceptions to this rule, which should be violated - freely and often: during the definition of variables, at the end of - closing braces, when used to comment parameters.
- +Explanation:
+It goes back to the question of readability. If the comment is on the same line as the code it will be + harder to read than the comment that is on its own line.
+There are three exceptions to this rule, which should be violated freely and often: during the definition of + variables, at the end of closing braces, when used to comment parameters.
Example:
-
-
-/*********************************************************************
+
|
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:
+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:
- -A reader of the code should be able to look at the comments just - prior to the beginning of a function and discern the reason for its - existence and the consequences of using it. The reader should not - have to read through the code to determine if a given function is - safe for a desired use. The proper information thoroughly presented - at the introduction of a function not only saves time for subsequent - maintenance or debugging, it more importantly aids in code reuse by - allowing a user to determine the safety and applicability of any - function for the problem at hand. As a result of such benefits, all - functions should contain the information presented in the addendum - section of this document.
+Explanation:
+A reader of the code should be able to look at the comments just prior to the beginning of a function and + discern the reason for its existence and the consequences of using it. The reader should not have to read + through the code to determine if a given function is safe for a desired use. The proper information thoroughly + presented at the introduction of a function not only saves time for subsequent maintenance or debugging, it + more importantly aids in code reuse by allowing a user to determine the safety and applicability of any + function for the problem at hand. As a result of such benefits, all functions should contain the information + presented in the addendum section of this document.
Explanation:
- -Each closing brace should be followed on the same line by a - comment that describes the origination of the brace if the original - brace is off of the screen, or otherwise far away from the closing - brace. This will simplify the debugging, maintenance, and readability - of the code.
- -As a suggestion , use the following flags to make the comment and - its brace more readable:
- -use following a closing brace: } /* -END- if() or while () or - etc... */
- +Explanation:
+Each closing brace should be followed on the same line by a comment that describes the origination of the + brace if the original brace is off of the screen, or otherwise far away from the closing brace. This will + simplify the debugging, maintenance, and readability of the code.
+As a suggestion , use the following flags to make the comment and its brace more readable:
+use following a closing brace: } /* -END- if() or while () or etc... */
Example:
-
-
-if ( 1 == X )
+
|
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++.
- +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; -+ int ms_iis5_hack = 0; |
Instead - of:
- +Instead of:
- -int msiis5hack = 0; int msIis5Hack = 0; -+ 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++.
- +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 ) -+ int load_some_file(struct client_state *csp) |
Instead - of:
- +Instead of:
- -int loadsomefile( struct client_state *csp ) -int loadSomeFile( struct client_state *csp ) -+ 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.
- +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 ) -+ (.h) extern int load_aclfile(struct client_state *csp); +(.c) int load_aclfile(struct client_state *csp) |
Instead - of:
- +Instead of:
- -(.h) extern int load_aclfile( struct client_state * ); or +(.h) extern int load_aclfile(struct client_state *); or (.h) extern int load_aclfile(); -(.c) int load_aclfile( struct client_state *csp ) -+(.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.)
- +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;
-
+ (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.
- +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 +#define FEATURE_FORCE 1 #ifdef FEATURE_FORCE #define FORCE_PREFIX blah -#endif /* def FEATURE_FORCE */ -+#endif /* def FEATURE_FORCE */ |
Explanation:
- +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.
- +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 -+ #define USE_IMAGE_LIST 1 |
Instead - of:
- +Instead of:
- -#define USE_IMG_LST 1 or +#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 -+#define UseImageList 1 |
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.
- +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 ) { ... }
- +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:
- +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 )
+
|
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.
- +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 )
+
|
Instead - of:
- -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.
+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 ); -+ 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-)
+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.
- +Explanation:
+Make it readable. The notable exception to using white space freely is listed in the next guideline.
Example:
-
- -int first_value = 0; +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 ) -+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.
- +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; a_struct.a_member; -function_name(); -+function_name(); |
Instead of: - 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( ... )
+
|
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.
+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.
- +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] =
+
|
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.
- +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; +short a_short = 0; float a_float = 0; -struct *ptr = NULL; -+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.
+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
- +Explanation:
+Value should be phrased as a question that would logically be answered as a true or false statement
Example:
-
- -should_we_block_this(); +should_we_block_this(); contains_an_image(); -is_web_page_blank(); -+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:
+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:
- +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.
- +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();
+
|
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.
+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:
+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:
+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 +
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 */ -+ #include <iostream.h> /* This is not a local include */ +#include "config.h" /* This IS a local include */ |
Exception:
- +Exception:
- -/* This is not a local include, but requires a path element. */ -#include <sys/fileName.h> -+ /* 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.
+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.
- +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 +#ifndef PROJECT_H_INCLUDED #define PROJECT_H_INCLUDED ... -#endif /* ndef 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.
- +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
+
|
Explanation:
- -Useful in headers that include pointers to other struct's. - Modifications to excess header files may cause needless compiles.
- +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; -+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.
+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
+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.
- +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 ) )
+
|
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.
+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:
+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:
- -On 32-bit platforms, int usually has the range of long. On 16-bit - platforms, int has the range of short.
- -Status: - open-to-debate. In the case of most FSF projects (including - X/GNU-Emacs), there are typedefs to int4, int8, int16, (or - equivalence ... I forget the exact typedefs now). Should we add these - to IJB now that we have a "configure" script?
+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:
- -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.
- +Explanation:
+It can be tempting to declare a series of variables all on one line. Don't.
Example:
-
- -long a = 0; +long a = 0; long b = 0; -long c = 0; -+long c = 0; |
Instead - of:
- +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: - 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.
- +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'. -+ 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.
- +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 ) { ... }
-
+ int load_re_filterfile(struct client_state *csp) { ... }
+static void unload_re_filterfile(void *f) { ... }
|
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).
+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:
+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:
- -/* FIXME: this code has a logic error on platform XYZ, * - attempting to fix */ #ifdef PLATFORM ...changed code here... - #endif
- +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:
- -/* FIXME: I think the original author really meant this... */ - ...changed code here...
- +/* XXX: I think the original author really meant this... */ ...changed code here...
or:
- -/* FIXME: 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).
+/* 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).
Example for file - comments:
- +Example for file comments:
-
-const char FILENAME_rcs[] = "$Id$";
-/*********************************************************************
+
|
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:
- +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:
- -#ifndef _FILENAME_H +#ifndef _FILENAME_H #define _FILENAME_H -#define FILENAME_H_VERSION "$Id$" /********************************************************************* * - * File : $Source$ + * File : $Source * * Purpose : (Fill me in with a good description!) * * Copyright : Written by and Copyright (C) 2001-2009 - * the Privoxy team. http://www.privoxy.org/ + * 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 @@ -1541,20 +991,15 @@ extern const char FILENAME_h_rcs[]; Local Variables: tab-width: 3 end: -*/ -+*/ |
Example for function - comments:
- +Example for function comments:
-
-/*********************************************************************
+
|
Note: If we - all follow this practice, we should be able to parse our code to create - a "self-documenting" web page.
+Note: If we all follow this practice, we should be able + to parse our code to create a "self-documenting" web page.