Coding style

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FPC compiler

Introduction

Some people might think that the coding style used by the FPC compiler sources and base rtl is a little bit strange but it has been used for a lot of years and isn't subject to be discussed. So take the following as a standard to be used.

Keywords

Write all keywords in lower case. There is no need to make them unreadble by writing them in upper case. Modern IDEs support syntax highlighting, so keywords will be easily recognizable.

Spaces

Don't use spaces around operators, colons, parentheses etc. e.g. write p:=p+i; instead of p := p + i ;.

TAB characters

Do not use TAB characters (ASCII HT, 0x09). There is no standard default TAB setting, so the look of source files using TAB characters will depend on client settings. This may result in a chaotic view of source files. Align by space characters (also see Indentation).

Indentation

Indentation size is always 2 space characters per level.

Never place a begin on the same line as while..do/if..then/..., but always on its own line (and indent it compared to the while/if/...).

Newlines

Newlines are set as it is done by most Object Pascal programs (what does this mean? advice: avoid passive voice). Separate subroutines by three newlines, that is, put two blank lines between them.

Misc

Please note that the else in consecutive ifs is not indented:

if x then
  begin
    ..
  end
else if y then
  begin
    ...
  end;

Split all composite if-conditions over multiple lines, so no "if (x) and (y) then" but

if x and
   y then
 ..

(except possibly if x and y are simply boolean variables)


Examples

How it looks like can be easily checked by having a look at the FPC sources.


Lazarus

Since Lazarus and LCL follows delphi compatibility, the similar code style is used.

If you're making patch or an extension for LCL you should follow its code style.

If you're developing your own component, you're free to use any style you like, but it's suggested to use LCL too.


You can find the description of Delphi coding style here

See also