Coding style: what changed

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Title: Coding style

New		Line
1	+	## FPC compiler and RTL
2	+
3	+	### Introduction
4	+
5	+	Some people might think that the coding style used in the FPC compiler and base RTL (run-time library) source code is a little bit strange. But it has been in use for a lot of years and is not subject to discussion. So take the following as a standard to be used.
6	+
7	+	### Keywords
8	+
9	+	Write all keywords in all lower snake_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.
10	+
11	+	### Spaces
12	+
13	+	Don't use spaces around operators, colons, parentheses etc.
14	+
15	+	``` pascal
16	+	{ correct }
17	+	p:=p+i;
18	+
19	+	{ incorrect }
20	+	p := p + i ;
21	+	```
22	+
23	+	Spaces in parameter lists. TODO: ???
24	+
25	+	``` pascal
26	+	function do_this(a: tdef; var b: tdef): boolean;
27	+	```
28	+
29	+	Spaces in variable lists. TODO: ???
30	+
31	+	``` pascal
32	+	var
33	+	a,b,c : tprocdef;
34	+	```
35	+
36	+	### TAB characters
37	+
38	+	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).
39	+
40	+	### Indentation
41	+
42	+	Indentation size is always 2 space characters per level.
43	+
44	+	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/...).
45	+
46	+	``` pascal
47	+	{ correct }
48	+	if true then
49	+	begin
50	+	end;
51	+
52	+	{ incorrect }
53	+	if true then begin
54	+	end;
55	+
56	+	{ incorrect }
57	+	if true then begin {...} end;
58	+	```
59	+
60	+	### Newlines
61	+
62	+	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.
63	+
64	+	### Comments
65	+
66	+	Comments should use curly brackets, be lower case and contain a single space between the {}.
67	+
68	+	``` pascal
69	+	{ this is an example of a comment }
70	+	```
71	+
72	+	### Routines
73	+
74	+	All sections (var, const, begin etc...) after routine header are indented one level.
75	+
76	+	``` pascal
77	+	procedure do_this;
78	+	var
79	+	sym: tsym;
80	+	begin
81	+	end;
82	+	```
83	+
84	+	No spaces after name and parenthesis for parameters.
85	+
86	+	``` pascal
87	+	procedure do_this(param: integer);
88	+	begin
89	+	end;
90	+	```
91	+
92	+	Nested functions are indented one level (the same level as other sections like var, const etc...)
93	+
94	+	``` pascal
95	+	procedure do_this;
96	+	var
97	+	i: integer;
98	+
99	+	{ nested function }
100	+	function getter: boolean;
101	+	begin
102	+	end;
103	+
104	+	var
105	+	x: integer;
106	+	begin
107	+	end;
108	+	```
109	+
110	+	Use result instead of function name for return values.
111	+
112	+	``` pascal
113	+	function getter: boolean;
114	+	begin
115	+	result:=true;
116	+	// wrong!
117	+	//getter:=true;
118	+	end;
119	+	```
120	+
121	+	### Classes/Records
122	+
123	+	Class sections should appear on the same indention level as the class name.
124	+
125	+	``` pascal
126	+	tloadnode = class(tunarynode)
127	+	protected
128	+	fprocdef : tprocdef;
129	+	public
130	+	constructor create(v : tsym;st : TSymtable);virtual;
131	+	end;
132	+	```
133	+
134	+	### Misc
135	+
136	+	Please note that the `else` in consecutive `if`s is not indented:
137	+
138	+	``` pascal
139	+	if x then
140	+	begin
141	+	..
142	+	end
143	+	else if y then
144	+	begin
145	+	...
146	+	end;
147	+	```
148	+
149	+	Split all composite if-conditions over multiple lines, so no "if (x) and (y) then" but
150	+
151	+	``` pascal
152	+	if p1.nodetype=ordconstn and
153	+	not is_boolean(p1.resultdef) and
154	+	not is_enum(p1.resultdef) then
155	+	begin
156	+	...
157	+	```
158	+
159	+	(except possibly if x and y are simply boolean variables)
160	+
161	+	Extraneous parenthesis in if statements: TODO: ???
162	+
163	+	``` pascal
164	+	if (pd.maxparacount>0) then
165	+	;
166	+	```
167	+
168	+	### Examples
169	+
170	+	How it looks like can be easily checked by having a look at the [FPC sources](http://www.freepascal.org/cgi-bin/viewcvs.cgi/?root=fpc).
171	+
172	+	## FCL
173	+
174	+	The FCL follows the same rules as above, with 1 exception: routines are not indented, and there are empty lines between the \`\`var\`\` section and surrounding code.
175	+
176	+	So do not write
177	+
178	+	``` pascal
179	+	procedure do_this;
180	+	var
181	+	sym: tsym;
182	+	begin
183	+	end;
184	+	```
185	+
186	+	But write
187	+
188	+	``` pascal
189	+	procedure do_this;
190	+
191	+	var
192	+	sym: tsym;
193	+
194	+	begin
195	+	end;
196	+	```
197	+
198	+	## Other packages distributed with FPC
199	+
200	+	There are no formal standards. To do: write me.
201	+
202	+	## Lazarus
203	+
204	+	Since Lazarus and LCL follow Delphi compatibility, a code style similar to the one used in Delphi is used.
205	+
206	+	If you're writing a patch or an extension for LCL you should follow its code style.
207	+
208	+	If you're developing your own component, you're free to use any style you like, but it's suggested to use the LCL style, too.
209	+
210	+	See the Lazarus coding guidelines: [[DesignGuidelines]]
211	+
212	+	For reference, you can find the description of Delphi coding style [here](http://edn.embarcadero.com/article/10280#8.2.3)
213	+
214	+	## See also
215	+
216	+	- [[DesignGuidelines\|Coding Guidelines for Lazarus]]
217	+
218	+	---
219	+	From the Free Pascal wiki, page "Coding style", as it stood on 2022-01-07 after a change by Michael, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).
220	+	Category: Coding style
221	+	Category: FPC
222	+	Category: FPC development
223	+	Category: Lazarus

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