Difference between revisions of "Coding standard"

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(File Operations)
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* C style strings. (replace them with C++ types where it is safe to do so)
 
* C style strings. (replace them with C++ types where it is safe to do so)
 
* goto
 
* goto
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=== File Operations ===
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When using file i/o based functions, such as fopen() etc or filename string functions, there are some that are not provided, ie retrieving the length of a file, checking if a file exists or not.
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Thankfully, Odamex provides some internal functions for doing such. Be sure to check out '''m_fileio.h''' before writing your own, it may have already been implemented! If it isn't, write us a patch and send it in.
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Some of the useful functions included are:
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* SDWORD M_FileLength(FILE *) - Returns the length of an open file handle
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 +
Filename operations:
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* BOOL M_FileExists(std::string Filename) - Checks if a file exists or not
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* BOOL M_AppendExtension(std::string &Filename, std::string Extension, bool If_Needed = true) - Add an extension on to the end of a filename, If_Needed detects if Extension is in the path, if it isn't, it is added
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* void M_ExtractFilePath(std::string Path, std::string &Destination) - Returns the path of a filename in Destination
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* BOOL M_ExtractFileExtension(std::string Filename, std::string &Destination) - Returns the extension of Filename in Destination
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* void M_ExtractFileBase(std::string Path, std::string &Destination) - Returns the base name of Path in Destination
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* void M_ExtractFileName(std::string Path, std::string &Destination) - Returns the complete filename of Path in Destination
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Others include:
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* BOOL M_WriteFile(std::string Filename, void *Buffer, QWORD Length) - Creates/overwrites a file and writes a block of data to it.
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* QWORD M_ReadFile(std::string Filename, BYTE **Buffer) - Allocates a buffer using Z_Malloc and reads the data into it from a file, lifetime is PU_STATIC.
  
 
=== Memory Management ===
 
=== Memory Management ===

Revision as of 00:36, 4 June 2008

Overview

Odamex relies on a coding standard to ensure continuity, this reduces bugs and provides easy readability of the code.

Requirements

  • Make logical changes in separate patches
  • Minimise the number of changes in each patch
  • Provide an off switch for every new feature
  • Do not submit things you cannot test (e.g. code for alternative platforms)

Code guidelines

General

  • Add a test for every change (or an explanation of why this is impossible)

Things you should definitely AVOID in your code:

  • Changing code that already works
  • Precompiler macros
  • Global variables (they can create problems elsewhere in code)
  • Variants (tagged unions) - they can present a performance problem
  • Magic numbers (use #define or const in your code for fixed numbers, at the top of files)
  • Hungarian notation (just plan evil)
  • C style strings. (replace them with C++ types where it is safe to do so)
  • goto

File Operations

When using file i/o based functions, such as fopen() etc or filename string functions, there are some that are not provided, ie retrieving the length of a file, checking if a file exists or not.

Thankfully, Odamex provides some internal functions for doing such. Be sure to check out m_fileio.h before writing your own, it may have already been implemented! If it isn't, write us a patch and send it in.

Some of the useful functions included are:

  • SDWORD M_FileLength(FILE *) - Returns the length of an open file handle

Filename operations:

  • BOOL M_FileExists(std::string Filename) - Checks if a file exists or not
  • BOOL M_AppendExtension(std::string &Filename, std::string Extension, bool If_Needed = true) - Add an extension on to the end of a filename, If_Needed detects if Extension is in the path, if it isn't, it is added
  • void M_ExtractFilePath(std::string Path, std::string &Destination) - Returns the path of a filename in Destination
  • BOOL M_ExtractFileExtension(std::string Filename, std::string &Destination) - Returns the extension of Filename in Destination
  • void M_ExtractFileBase(std::string Path, std::string &Destination) - Returns the base name of Path in Destination
  • void M_ExtractFileName(std::string Path, std::string &Destination) - Returns the complete filename of Path in Destination

Others include:

  • BOOL M_WriteFile(std::string Filename, void *Buffer, QWORD Length) - Creates/overwrites a file and writes a block of data to it.
  • QWORD M_ReadFile(std::string Filename, BYTE **Buffer) - Allocates a buffer using Z_Malloc and reads the data into it from a file, lifetime is PU_STATIC.

Memory Management

If you need to use malloc(), calloc(), realloc(), free() functions. Use the macros located in m_alloc.h, these are provided because they are much better when it comes to debugging code and such:

  • M_Malloc(size_t Size)
  • M_Calloc(size_t Items, size_t Size)
  • M_Realloc(void *Pointer, size_t Size)
  • M_Free(uintptr_t &Reference)

A list of features these functions offer:

  • The Size value can NEVER be 0, this prevents platform-specific behaviour.
  • M_Free uses a reference instead of a pointer, it still does the same as normal free(), but will NULL the address on return.
  • They will abort the program if their operation fails.

Z_Zone Memory Management

  • Be aware that the all Z_Zone allocated memory is freed when the WAD changes

Formatting

  • If creating a new file, include a GPL header at the top of it, as seen in other files.
  • Descriptive comments
  • Comments of reasonable size. (not too big and not too small)
  • Comment formatting. (in c/c++, either // for 1 liners or /* */ for multiple lines)
  • Indentations to be of 1 tab character, using 4 space width tabs
  • Be sure your editor/IDE's EOL mode is LF, not CRLF or CR
  • 80 line character limit, for devs with text-based editors
  • if you can, limit functions to a maximum size (like the amount that would fit on a monitor with a reasonable screen resolution)

What you should strive for:

  • Clarity of code
  • Defensive and secure coding practices
  • Maintain traditional naming conventions, for consistency

External Links