Chelper: what changed

Revision 3 to 4. Removed lines have a minus sign; added lines have a plus sign.

Old	New		Line
1	1		### About
2	2
3	3		Chelper is Lazarus extension tool, that helps converting C headers to Pascal. Yes, it's yet another C-to-Pascal converting tool like lot of similar ([[H2Pas]], ToPas), but one might find it more useful.
4	4
5	5		The extension doesn't try to convert a header for the user, instead it's a tool to help with manual translation, doing almost all of "dirty work" for the user.
6	6
7	7		Chelper also supports converting Objective-C declarations into Objective-P.
8	8
9	9		### Author
10	10
11	11		Dmitry 'skalogryz' Boyarintsev
12	12
13	13		### License
14	14
15	15		[modified](http://svn.freepascal.org/svn/lazarus/trunk/COPYING.modifiedLGPL) [LGPL](http://svn.freepascal.org/svn/lazarus/trunk/COPYING.LGPL) (same as the FPC RTL and the Lazarus LCL). You can contact the author if the modified LGPL doesn't work with your project licensing.
16	16
17	17		### Download
18	18
19	19		There's no "downloadable" package yet, you can access the tool from SVN:
20	20
21	21		<https://sourceforge.net/p/lazarus-ccr/svn/HEAD/tree/components/chelper/>
22	22
23		-	~~```~~
	23	+	```text
24	24		svn checkout https://svn.code.sf.net/p/lazarus-ccr/svn/components/chelper/
25	25		```
26	26
27	27		### Change Log
28	28
29	29		- Version 0.8, 8 Aug 2010
30	30
31	31		### Dependencies / System Requirements
32	32
33	33		- Lazarus 0.9.29 or Higher
34	34
35	35		Status: Beta
36	36
37	37		### Issues
38	38
39	39		- No complete expression parser to construct the expression tree.
40	40
41	41		If you find a bug in the converter please report it to [bugs.freepascal.org](http://bugs.freepascal.org) for Lazarus-CCR project. Please attach the C-header text and the explanation what doesn't work as expected.
42	42
43	43		### Installation
44	44
45	45		- Get the package from SVN
46	46		- Install Chelper.lpk package to the Lazarus.
47	47		- Go to Tools-\>C to Pascal Options-\>Converter, uncheck Use external converter if you want to use the package built-in converter.
48	48
49	49		Using built-in converter has an advantage of the performance. However, if you'll need to update converter, you'll need to rebuild the whole IDE. It's also possible that converter might cause crashes or hangs. You should bug report it, but you're risking to loose all of your data.
50	50
51	51		It's much safer to use the external cconvert tool. It's also easier to update the converter if a new features are added or bugs fixed. All you need is to rebuild the cconverter executable a lot of faster than rebuilding Lazarus.
52	52
53	53		To use the external tool, you need to do the following:
54	54
55	55		- Open and build cconvert.lpi project (located at the package directory). You should get "cconvert" executable file.
56	56		- Open Tools-\>C to Pascal Options-\>Converter, press Select and choose cconvert executable file.
57	57		- Check Use external converter at Tools-\>C to Pascal Options-\>Converter
58	58
59	59		### How to use
60	60
61	61		#### Shortkeys
62	62
63	63		- ctrl+b - convert a single C declaration to Pascal
64	64		- ctrl+shift+b - convert all C declarations to Pascal from the current cursor position to the end of the file.
65	65
66	66		#### General
67	67
68	68		- Open a file with C declarations in Lazarus IDE or start a new file copying declarations there
69	69		- Place the cursor at the line where C declaration and press Ctrl+B (the shortcut would be modifiable in future).
70	70
71	71		for example:
72	72
73		-	~~```~~
	73	+	```text
74	74		int c;
75	75		int b;
76	76		```
77	77
78	78		if the cursor placed at 'inc c;' line and ctrl+b pressed the result would be:
79	79
80	80		``` pascal
81	81		var
82	82		c : Integer;
83	83		int b;
84	84		```
85	85
86	86		exactly one definition is converted. The cursor would be place right after the converted definition. You can press ctrl+b again, and the result would be:
87	87
88	88		``` pascal
89	89		var
90	90		c : Integer;
91	91		var
92	92		b : Integer;
93	93		```
94	94
95	95		Parsing definitions one-by-one will get your C headers ready with a very short period of time, as well as keeping it clean and correct from Pascal point of view.
96	96
97	97		- If you're sure your defines (explained below) are configured well enough. You can try to convert the rest of the file in one call by pressing ctrl+shift+b
98	98
99	99		i.e. you have 2 declarations in the file:
100	100
101		-	~~```~~
	101	+	```text
102	102		int fn(int, float);
103	103		extern int v;
104	104		```
105	105
106	106		placing the cursor before them and pressing ctrl+shift+b, would generate.
107	107
108	108		``` pascal
109	109		function fn(par0: Integer; par1: Single): Integer; cdecl; external;
110	110
111	111		var
112	112		v : Integer; external;
113	113		```
114	114
115	115		You must be careful, because it's common to use macros in C headers. Leaving any of macros undefined might produce wrong pascal declaration. The next section explains how to define a macro for the chelper.
116	116
117	117		#### Defines
118	118
119	119		In most cases parameterless macro definitions, like
120	120
121		-	~~```~~
	121	+	```text
122	122		#define VALUE 1 << 2;
123	123		```
124	124
125	125		are used like constant values. Chelper translates them as constants trying to convert the define expression.
126	126
127	127		``` pascal
128	128		const
129	129		VALUE = 1 shr 2;
130	130		```
131	131
132	132		In other cases defines are used for some "special" markings or additional information for external tools.
133	133
134		-	~~```~~
	134	+	```text
135	135		#define LIB_DEPRECATED
136	136		LIB_DEPRECATED int somefunc(int p);
137	137		```
138	138
139	139		without the knowledge of LIB_DEPRECATED being the macro (of nothing), it's impossible to parse function declaration correctly. You can specify macros used by Chelper in the special defines file.
140	140
141	141		Select Tools-\>C to Pascal options-\>Main select the defines file and press Edit.
142	142
143	143		This would open the custom defines file in Lazarus IDE. All macros declared at this file are used by Chelper. After adding/editing macro defines save the file and you can return to the C header converting.
144	144
145	145		Chelper handles parameter macros as well.
146	146
147		-	~~```~~
	147	+	```text
148	148		int somefunc SAFE_PARAMS( (int i))
149	149		```
150	150
151	151		adding the the following declaration into defines file
152	152
153		-	~~```~~
	153	+	```text
154	154		#define SAFE_PARAMS(x) x
155	155		```
156	156
157	157		will allow to parse the declaration correctly
158	158
159	159		``` pascal
160	160		function somefunc(i: Integer): Integer;
161	161		```
162	162
163	163		#### Configuration File
164	164
165	165		Configuration file represents itself a simple .ini file. Following section are used in the file:
166	166
167	167		- Main - for general declarations, that effects
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169	169		- Types - custom type conversion section. Name=Value, where Name is the c-type name, Value is resulting pascal type
170	170
171	171		example:
172	172
173		-	~~```~~
	173	+	```text
174	174		[Types]
175	175		int=integer
176	176		int*=PInteger
177	177		float=single
178	178		float*=PSingle
179	179		```
180	180
181	181		---
182	182		From the Free Pascal wiki, page "Chelper", as it stood on 2022-04-30 after a change by E-ric, 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).

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