use an enum instead of strings as IndexTarget::Option interface

[apt.git] / doc / style.txt

Acronyms
~~~~~~~~
* dpkg is a 'word' the first d may be upper case - Dpkg
* APT is a proper Acronym, all upper case please.

Pkg - A Package
Ver - A version

Indenting, Comments, Etc
~~~~~~~~~~~~~~~~~~~~~~~~
Would make Linus cry :P However it is what I prefer. 3 space indent,
8 space tab all braces on separate lines, function return on the same line
as the function, cases aligned with their code. The 'indent' options for 
this style are:
   indent -bl -bli0 -di1 -i3 -nsc -ts8 -npcs -npsl

Each file gets a block at the top that should describe what the file does,
basically a summary of purpose along with any special notes and 
attributions. The }}} and {{{ are folding marks if you have a folding
editor such as jed, the function separators are intended to give
a visual separate between functions for easier browsing of the larger files,
or indexed folding if you have such an editor.

Each file should have 1 or 0 primary include files, that include
file must always be the first include file included by the .cc. G++ 
#pragma interface/implementation is used, as well as anti-include-twice
#ifdefs.

Include files, since there are so many, get their own subdirectory off
the include search path, this is used consistently throughout all the code.
#include "" should never be used for a global exported header file, only 
local ones.

C++ Features
~~~~~~~~~~~~
Due to the legacy compiler heritage, exceptions, RTTI and name spaces are
not used. Templates are used *sparingly* since G++ has traditionally had
very weak support for them, this includes STL templates.

Namespaces will probably be put in the code sometime after G++ 3, which will
be a huge re-org again to make sanity, the majority of all nested things
will go away.

The C++ standard library's non parameterized types (string is included in
this) are used freely when appropriate.

The new C++ #include <iostream> (note the lack of a .h) is used for the
standard library, but not for my code.

Arguments and Ownership
~~~~~~~~~~~~~~~~~~~~~~~
[much of the code follows this now]
These guidlines should be followed except in two cases.. the first
is where it makes no sense, such as in a casting operator and the second is to
retain API compatibility (this should be rare, since a change in the input
almost always designates a change in ownership rules).

  * Pass by value or pass by reference should borrow the object from the
    caller
  * Pass by non-const reference may be used to indicate a OUT type variable
  * Pass by pointer (except in the case where the pointer is really an array)
    should be used when the object will be retained or ownership will be
    transferred. Ownership transference should be rare and noted by a comment.
  * Standard C things (FILE * etc) should be left as is.
  
  * Return by references should indicate a borrowed object
  * Return by pointer (except arrays) should indicate ownership is 
    transferred. Return by pointer should not be used unless ownership is
    transferred.
  * Return by pointer to variable indicates ownership transfer unless the
    pointer is an 'input' parameter (designated generally by an =0, 
    indicating a default of 'none')
     
Non-ownership transferring arrays/lists should probably return an iterator 
typedef or references..