Reserved words: what changed

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1	1		The keywords of the individual [compiler modes](/wiki-category/Modes) are summarized as follows:
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3	3		- [[Mode TP\|Turbo Pascal mode]]: the [[Turbo Pascal]] keywords are available for you to use
4	4		- [[Mode Delphi\|Delphi mode]]: the Turbo Pascal and Object Pascal keywords are available for you to use
5	5		- [[Mode ObjFPC\|Extended Free Pascal mode]]: the Turbo Pascal and Object Pascal keywords are available for you to use
6	6
7	7		Keywords are reserved words, ie they cannot be defined as [[Identifier\|identifiers]] by the programmer. This means that you cannot use these words to name your variables, constants, function and procedure names, class names, etc. In Pascal, in the source code, keywords are often shown in bold.
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9	9		## Reserved words in Turbo Pascal
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11	11		The following keywords occur in Turbo Pascal mode:
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13	13		\| Keyword \| Description \|
14	14		\|----\|----\|
15	15		\| [[And\|and]] \| Boolean operator requiring both conditions are true for the result to be true \|
16	16		\| [[Array\|array]] \| multiple elements with the same name \|
17	17		\| [[Asm\|asm]] \| start of code written in assembly language \|
18	18		\| [[Begin\|begin]] \| start of a [[Block\|block]] of code \|
19	19		\| [[Break\|break]] \| exit a loop \|
20	20		\| [[Case\|case]] \| select a particular segement of code to execute based on a value \|
21	21		\| [[Const\|const]] \| declare an identifier with a fixed value, or a variable with an initialized value \|
22	22		\| [[Constructor\|constructor]] \| routine used to create an object \|
23	23		\| [[Continue\|continue]] \| skips an iteration in a loop and restart execution at the beginning of the loop \|
24	24		\| [[Destructor\|destructor]] \| routine used to deallocate an object \|
25	25		\| [[Div\|div]] \| integer divide operator \|
26	26		\| [[Do\|do]] \| used to indicate start of a loop \|
27	27		\| [[Downto\|downto]] \| used in a [[For\|for]] loop to indicate the index variable is decremented \|
28	28		\| [[Else\|else]] \| used in [[If\|if]] statement to provide an execution path when the if test fails \|
29	29		\| [[End\|end]] \| end of a block of code, a record or certain other constructs \|
30	30		\| [[False\|false]] \| boolean value indicating a test failed; opposite of [[True\|true]]. As of FPC 3.0.0. False is no longer a keyword. \|
31	31		\| [[File\|file]] \| external data structure, typically stored on disc \|
32	32		\| [[For\|for]] \| loop used to increment or decrement a control variable \|
33	33		\| [[Function\|function]] \| define start of a routine that returns a result value \|
34	34		\| [[Goto\|goto]] \| used to exit a segment of code and jump to another point \|
35	35		\| [[If\|if]] \| test a condition and perform a set of instructions based on the result \|
36	36		\| [[Implementation\|implementation]] \| define the internal routines in [[Unit\|unit]] \|
37	37		\| [[In\|in]] \| identifies elements in a collection \|
38	38		\| [[Inline\|inline]] \| machine code inserted directly into a routine \|
39	39		\| [[Interface\|interface]] \| public declarations of routines in a [[Unit\|unit]] \|
40	40		\| [[Label\|label]] \| defines the target jump point for a [[Goto\|goto]] \|
41	41		\| [[Mod\|mod]] \| operator used to return the remainder of an integer division \|
42	42		\| [[Nil\|nil]] \| pointer value indicating the pointer does not contain a value \|
43	43		\| [[Not\|not]] \| boolean operator that negates the result of a test \|
44	44		\| [[Object\|object]] \| defines an object construct \|
45	45		\| [[Of\|of]] \| defines the characteristics of a variable \|
46	46		\| [[On\|on]] \| defines an exception handling statement in the [[Except]] part of a [[Try]] statement \|
47	47		\| [[Operator\|operator]] \| defines a routine used to implement an operator \|
48	48		\| [[Or\|or]] \| boolean operator which allows either of two choices to be used \|
49	49		\| [[Packed\|packed]] \| indicates the elements of an array are to use less space (this keyword is primarily for compatibility with older programs as packing of array elements is generally automatic) \|
50	50		\| [[Procedure\|procedure]] \| define start of a routine that does not return a result value \|
51	51		\| [[Program\|program]] \| defines start of an application. This keyword is usually optional. \|
52	52		\| [[Record\|record]] \| group a series of variables under a single name \|
53	53		\| [[Repeat\|repeat]] \| loop through a section of code through an [[Until\|until]] statement as long as the result of the test is true \|
54	54		\| [[Set\|set]] \| group a collection \|
55	55		\| [[Shl\|shl]] \| operator to shift a value to the left; equivalent to multiplying by a power of 2 \|
56	56		\| [[Shr\|shr]] \| operator to shift a value to the right; equivalent to dividing by a power of 2 \|
57	57		\| [[String\|string]] \| declares a variable that contains multiple characters \|
58	58		\| [[Then\|then]] \| indicates start of code in an [[If\|if]] test \|
59	59		\| [[To\|to]] \| indicates a [[For\|for]] variable is to be incremented \|
60	60		\| [[True\|true]] \| boolean value indicating a test succeeded; opposite of [[False]]. As of FPC 3.0.0. True is no longer a keyword. \|
61	61		\| [[Type\|type]] \| declares kinds of records or new classes of variables \|
62	62		\| [[Unit\|unit]] \| separately compiled module \|
63	63		\| [[Until\|until]] \| indicates end test of a [[Repeat\|repeat]] statement \|
64	64		\| [[Uses\|uses]] \| names [[Unit\|units]] this program or unit refers to \|
65	65		\| [[Var\|var]] \| declare variables \|
66	66		\| [[While\|while]] \| test a value and if true, loop through a section of code \|
67	67		\| [[With\|with]] \| reference the internal variables within a record without having to refer to the record itself \|
68	68		\| [[Xor\|xor]] \| boolean operator used to invert and [[Or\|or]] test \|
69	69
70	70		## Reserved words in Object Pascal
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72	72		Object Pascal extends the (Turbo) Pascal language with both support for dealing more easily with objects (object orientation) as well as other newer/more advanced concepts (threads, etc).
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74	74		In addition to the reserved words in Turbo Pascal, the following reserved words are available in Delphi mode as well:
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76	76		\| Keyword \| Description \|
77	77		\|----\|----\|
78	78		\| [[As\|as]] \| performs a conditional typecast \|
79	79		\| [[Class\|class]] \| a highly structured data type in Object Pascal dialects such as Delphi or the ObjFPC \|
80	80		\| [[Constref\|constref]] \| \|
81	81		\| [[Dispose\|dispose]] \| releases the memory allocated for a pointer variable allocated using new \|
82	82		\| [[Except\|except]] \| only used in conjunction with try \|
83	83		\| [[Exit\|exit]] \| immediately leaves the surrounding block \|
84	84		\| [[Exports\|exports]] \| exports symbols which will be publicly available \|
85	85		\| [[Finalization\|finalization]] \| introduces an optional 'finalization' part of a unit \|
86	86		\| [[Finally\|finally]] \| part of a try - finally - end block \|
87	87		\| [[Inherited\|inherited]] \| calls function/procedure from ancestor class \|
88	88		\| [[Initialization\|initialization]] \| introduces an optional 'initialization' part of a unit \|
89	89		\| [[Is\|is]] \| can be used as an [[Operator\|operator]] or a [[modifier]] \|
90	90		\| [[Library\|library]] \| used in a shared library unit instead of the reserved word [[Unit\|unit]] \|
91	91		\| [[New\|new]] \| creates a new dynamic variable and sets a pointer variable to point to it \|
92	92		\| [[On\|on]] \| checks against one of a number of exception classes \|
93	93		\| [[Out\|out]] \| \|
94	94		\| [[Property\|property]] \| allow various levels (read, read/write etc) outside access to variables inside a class \|
95	95		\| [[Raise\|raise]] \| causes an exception \|
96	96		\| [[Self\|self]] \| reference to an instance of a class \|
97	97		\| [[Threadvar\|threadvar]] \| declare global variable to be thread local \|
98	98		\| [[Try\|try]] \| part of Try .. Finally or Try .. Exception block \|
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100	100		## Reserved words in Extended Free Pascal
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102	102		The reserved words in [[Mode ObjFPC\|Extended Free Pascal mode]] include:
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104	104		- [[Mode TP\|Turbo Pascal mode]] reserved words
105	105		- [[Mode Delphi\|Object Pascal mode]] reserved words\
106	106
107	107		## Modifiers (directives)
108	108
109	109		Modifiers are not strictly reserved words; however they are used in the same way as reserved words.
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111	111		See the [Free Pascal Reference Guide](https://www.freepascal.org/docs-html/current/ref/ref.html) for details.
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113	113		\| Modifiers \| Description \|
114	114		\|----\|----\|
115	115		\| [[Absolute\|absolute]] \| \|
116	116		\| [[abstract]] \| an abstract class cannot be instantiated, only inherited \|
117	117		\| [[alias]] \| \|
118	118		\| [[assembler]] \| pure assembler routine: routine is defined by [[Asm\|asm]] … [[End\|end]] \|
119	119		\| [[cdecl]] \| C declaration modifier \|
120	120		\| [[Cppdecl]] \| C++ declaration modifier \|
121	121		\| [[default]] \| For indexed properties to use them without specifying the property name \|
122	122		\| [[export]] \| \|
123	123		\| [[external]] \| \|
124	124		\| [[Forward\|forward]] \| Allow a subroutine to be used before it is declared \|
125	125		\| [[generic]] \| class creation modifier \|
126	126		\| [[index]] \| \|
127	127		\| [[Local\|local]] \| A function/procedure modifier only usable with Linux (for Kylix compatibility) \|
128	128		\| [[name]] \| \|
129	129		\| [[nostackframe]] \| compiler hint: omit stack frame if possible \|
130	130		\| [[oldfpccall]] \| deprecated subroutine calling convention \|
131	131		\| [[Override\|override]] \| overriding of virtual functions \|
132	132		\| [[pascal]] \| use classic pascal calling convention \|
133	133		\| [[Private\|private]] \| private accessibility modifier, only class members can access data/functions/procedures \|
134	134		\| [[Protected\|protected]] \| protected accessibility modifier, accessibility modifier, class members and inherited classes can access data/functions/procedures \|
135	135		\| [[Public\|public]] \| public accessibility modifier, public access to data/functions/procedures \|
136	136		\| [[Published\|published]] \| accessibility modifier, published properties are visible in IDE ar can be written to .lfm \|
137	137		\| [[Read\|read]] \| property read access \|
138		-	~~\| [[Register\|register]] \| define routine’s calling convention: pass first n parameters via <abbr title="general purpose register">GPR</abbr>s \|~~
	138	+	\| [[Register\|register]] \| define routine’s calling convention: pass first n parameters via GPRs \|
139	139		\| [[Reintroduce\|reintroduce]] \| \|
140	140		\| [[Safecall\|safecall]] \| subroutine calling convention \|
141	141		\| [[softfloat]] \| \|
142	142		\| [[specialize]] \| specialization of [[Generics\|generic classes]] \|
143	143		\| [[Stdcall\|stdcall]] \| subroutine calling convention \|
144	144		\| [[Virtual\|virtual]] \| describes a virtual method in OO programming \|
145	145		\| [[Write\|write]] \| property write access \|
146	146		\| \| \|
147	147
148	148		## Unsupported Turbo Pascal modifiers
149	149
150	150		> Note: These modifiers are supported in the [[DOS]] cross compiler present in the FPC development version
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152	152		The reason why these modifiers are not supported is that these modifiers deal with 16 bit code for DOS. In other words, these modifiers have special meaning for 16 bit programming under DOS and Windows 3.x.
153	153
154	154		As Free Pascal does not support 16 bit code (only 32 and 64 bit), these modifiers are irrelevant in Free Pascal code.
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156	156		\| \| \|
157	157		\|----\|----\|
158	158		\| [[Far\|far]] \| access addresses outside of the current 64KB segment \|
159	159		\| [[Near\|near]] \| access addresses in the current 64KB segment \|
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161	161		## More functionality
162	162
163	163		Apart from the language features provided by the reserved words/keywords mentioned above, there is a lot of functionality available for the programmer in the various libraries:
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165	165		- [[RTL]]: Run-Time Library, available for all FPC and Lazarus programs
166	166		- [[FCL]]: Free Component Library: a core set of libraries available for Lazarus programs and usually for FPC (FPC can be compiled without it, but that only happens on purpose for low-memory embedded systems etc)
167	167		- FPC Packages: other packages provided by FPC
168	168		- Lazarus components: these are Lazarus components that can be dropped on a form and often based on FCL or FPC packages
169	169		- Lazarus utility functions: e.g. the [fileutil](http://wiki.lazarus.freepascal.org/Category:fileutil) unit.
170	170
171	171		Apart from the libraries provided by FPC and Lazarus, there are more libraries/components available:
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173	173		- FPC user-supplied units: see the FPC wiki
174	174		- Lazarus CCR: components
175	175		- User-supplied code on the internet: see open source repositories like SourceForge and GitHub.
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177	177		## See also
178	178
179	179		- [[Pascal basics]]
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181	181		---
182	182		From the Free Pascal wiki, page "Reserved words", as it stood on 2024-05-19 after a change by Kberov, 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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