XEmacs / etc / CODING-STANDARDS

			XEMACS CODING STANDARDS
				   
				  by

			       Ben Wing


Copyright (c) 1996 Ben Wing.


This file documents the coding standards used in the XEmacs source
code.  Note that XEmacs follows the GNU coding standards, which are
documented separately in ../man/standards.texi.  This file only
documents standards that are not included in that document; typically
this consists of standards that are specifically relevant to the
XEmacs code itself.

First, a recap of the GNU standards:

-- Put a space after every comma.
-- Put a space before the parenthesis that begins a function call,
   macro call, function declaration or definition, or control
   statement (if, while, switch, for). (DO NOT do this for macro
   definitions; this is invalid preprocessor syntax.)
-- The brace that begins a control statement (if, while, for, switch,
   do) or a function definition should go on a line by itself.
-- In function definitions, put the return type and all other
   qualifiers on a line before the function name.  Thus, the function
   name is always at the beginning of a line.
-- Indentation level is two spaces.  (However, the first and following
   statements of a while/for/if/etc. block are indented four spaces
   from the while/for/if keyword.  The opening and closing braces are
   indented two spaces.)
-- Variable and function names should be all lowercase, with underscores
   separating words, except for a prefixing tag, which may be in
   uppercase.  Do not use the mixed-case convention (e.g.
   SetVariableToValue ()) and *especially* do not use Microsoft
   Hungarian notation (char **rgszRedundantTag).
-- preprocessor and enum constants should be all uppercase, and should
   be prefixed with a tag that groups related constants together.


Now, the XEmacs coding standards:

**** Specially-prefixed functions/variables:

-- All global C variables whose value is constant and is a symbol begin
   with a capital Q, e.g. Qkey_press_event. (The type will always be
   Lisp_Object.)
-- All other global C variables whose value is a Lisp_Object (this
   includes variables that forward into Lisp variables plus others like
   Vselected_console) begin with a capital V.
-- No C variables whose value is other than a Lisp_Object should begin
   with a capital V. (This includes C variables that forward into
   integer or boolean Lisp variables.)
-- All global C variables whose value is a struct Lisp_Subr begin with a
   capital S. (This only occurs in connection with DEFUN ()).
-- All C functions that are Lisp primitives begin with a capital F,
   and no others should begin this way.

**** Functions for manipulating Lisp types:

-- Any function that creates an empty or mostly empty Lisp object
   should begin allocate_(). (*Not* make_().) (Except, of course,
   for Lisp primitives, which usually begin Fmake_()).
-- Any function that converts a pointer into an equivalent Lisp_Object
   should begin make_().
-- Any function that converts a Lisp_Object into its equivalent pointer
   and checks the type and validity of the object (e.g. making sure
   it's not dead) should begin decode_().
-- Any function that looks up a Lisp object (e.g. buffer, face) given
   a symbol or string should begin get_(). (Except, of course, for
   Lisp primitives, which usually begin Fget_()).

**** Other:

-- Any header-file declarations of the sort

   struct foobar;

   go into the "types" section of lisp.h.
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