1/* 2 * Copyright 2007 Niels Sascha Reedijk. All rights reserved. 3 * Copyright 2008-2013, 2020 Haiku, Inc. All rights reserved. 4 * Distributed under the terms of the MIT License. 5 * 6 * Authors: 7 * Niels Sascha Reedijk, niels.reedijk@gmail.com 8 * John Scipione, jscipione@gmail.com 9 * 10 * Proofreaders: 11 * Alan Smale, ajsmale@gmail.com 12 */ 13 14 15/*! 16 \page apidoc Documenting the API 17 18 This article explains how to document the API. Its intended audience are the 19 Haiku developers who want to document their own classes, and also the 20 members of the API Documentation team who want to brush up the 21 documentation. The guidelines are synchronous with the Haiku Coding 22 Guidelines, which means that the formal requirements are the same where 23 applicable. If you find an inconsistency, it's usually a good idea to 24 report this on the documentation team's mailing list. 25 26 This document is divided into three sections. \ref formalrequirements 27 describes the demands that are made from the markup and spacing of the 28 files. \ref commands describes the subset of Doxygen commands the Haiku API 29 documentation uses, and which commands are used in which situation. \ref 30 style describes the required style and structure of the documentation. If 31 you are a developer and you want to prepare the first version of the 32 documentation for the API documentation team to go over, have a good look at 33 the formal requirements and the Doxygen commands. In addition, have a quick 34 glance at how to write member and class documentation, since you'll need to 35 know which information is mandatory for the documentation. Aspiring members 36 or members of the API documentation team should read the third section 37 carefully, and should also check out some of the finished documentation to 38 get a good grip on the actual tone, style and contents of the documentation. 39 40 \section formalrequirements Formal Requirements 41 42 This section describes formal requirements, such as location and naming of 43 the files, the header blocks of files, what blocks of documentation look 44 like and how to put delimiters to separate different 'blocks' in your source 45 file. 46 47 \subsection formalrequirements_location Location of the Documentation Source 48 49 Doxygen, the tool that we use to generate the marked up documentation, has 50 an ingenious parser that is able to scan through both header and source 51 files making it possible to document the API directly in the headers or the 52 source. However, the Haiku project have decided not to put the documentation 53 in either location, and opt for the third option Doxygen provides: to put 54 the documentation into separate files. 55 56 \note The reasons to not put the documentation in the header files are twofold. 57 First of all, it would add unnecessary cruft to the headers that the 58 compiler will needlessly have to parse, and developers will have a hard 59 time to find the info they are looking for. The second reason is that 60 the system headers are included throughout the tree. It's a waste of 61 electricity to have everybody recompile the entire tree if someone fixes 62 a typo in the documentation. Likewise, the reason to not put the 63 documentation in the source code is that it unnecessarily clutters up 64 that file. By not using direct documentation we lose some advantages, 65 like the fact that developers might be inclined to update the 66 documentation quicker if they change a method, but as you will see we'll 67 have some methods in place to prevent that to a certain extent. 68 There are a few aspects to the naming and locations of files: 69 -# Most important, documentation files \b mirror header files. This 70 not only means that they get the same name, but also that the order 71 of the methods, variables, functions, etc. will have to be the same. 72 -# The root directory of the public API headers is at \c 73 headers/os. In a similar vein, the root of the documentation 74 files is at \c docs/user. The subdirectory 75 structure, or the division of kits, will also be replicated. 76 -# The name of the files is the same as the base of the header files, 77 with the \c dox extension. So \c Something.h becomes \c 78 Something.dox. Note the case! 79 80 \subsection formalrequirements_headerblock The Header Block 81 82 Every documentation file will begin with the header block. It's basically a 83 copyright block, with a reference to the author(s) and against which 84 revision the documentation was written. 85 86\verbatim 87/* 88 * Copyright 2007-2013 Haiku, Inc. All rights reserved. 89 * Distributed under the terms of the MIT License. 90 * 91 * Authors: 92 * Niels Sascha Reedijk, niels.reedijk@gmail.com 93 * 94 * Proofreaders: 95 * Alan Smale, ajsmale@gmail.com 96 * 97 * Corresponds to: 98 * headers/os/support/String.h rev 19731 99 * src/kits/support/String.cpp rev 19731 100 */ 101\endverbatim 102 103 The example above has a few elements that you should take note of: 104 -# The header is put in a standard C comment, which is enclosed between 105\verbatim 106/* 107\endverbatim 108 and 109\verbatim 110*/ 111\endverbatim 112 -# Every line starts with a whitespace and an asterisk followed by another 113 space. If the text is part of a category, such as <tt>Authors</tt>, put 114 three spaces after the delimiter. 115 -# The first line is empty, then we get to the copyright notice. You may 116 either retain the copyright yourself, or you can attribute to to Haiku 117 Inc. It's your choice. The next line is the \e MIT License notice, 118 followed by an empty line. 119 -# Then there is a label <tt>Authors:</tt>, which is followed by 120 lines with names and email addresses. The latter one is optional, but 121 recommended. Each author is proceeded by two tabs after the asterisk. 122 -# In the same vein there is the label <tt>Proofreaders:</tt> in case the 123 file has been proofread. 124 -# The final part is underneath the label <tt>Corresponds to:</tt>. 125 Underneath there is a list of files and their svn revisions that the 126 current documentation is known to correspond with. 127 -# The header block ends with the 128\verbatim 129*/ 130\endverbatim 131 where the asterisk is aligned with the ones above it. 132 133 \subsection formalrequirements_blocks Blocks 134 135 Blocks are the basic units of documentation for Doxygen. At first it will 136 feel like overkill to use blocks, but realize that Doxygen was initially 137 designed to operate on header and source files, and then the blocks of 138 documentation would be before the definition or declaration of the methods, 139 functions, etcetera. Doxygen is used to operating on blocks, and that's why 140 we need to reproduce them in our \c dox files. 141 142 Blocks should adhere to the following standards: 143 -# All blocks open with 144\verbatim 145/*! 146\endverbatim 147 and close with 148\verbatim 149*/ 150\endverbatim 151 -# The documentation is placed in between these markers. 152 -# All the contents in between the markers is indented by tabs. The tab 153 length should be four. 154 -# Between blocks, there should be two empty lines. 155 -# The maximum width of the contents between blocks is 80 columns. <b>Try 156 not to cross this limit</b>, because it will severely limit 157 readability. 158 159 Example: 160\verbatim 161/*! 162 \fn bool BList::AddItem(void *item) 163 \brief Append an item to the list. 164 165 \param item The item to add. 166 \retval true The item was appended. 167 \retval false Item was not appended, since resizing the list failed. 168 \sa AddItem(void *item, int32 index) 169*/ 170\endverbatim 171 172 \note Doxygen also allows the use of single line comments, starting with 173 \c //!, however, we won't use these \b except for group markers, which 174 you can read more about in the next section. 175 176 \subsection formalrequirements_delimiters Delimiters 177 178 Many of the header files in the Haiku API just document one class or one 179 group of functions. However, there be a time when you come across a more 180 complex header and for the sake of clarity in your \c dox file you want to 181 mark the sections. Use the standard delimiter marker for this, which 182 consists of five slashes, a space, the title of the section, a space and 183 another five slashes. Like this: <tt>///// Global Functions /////</tt>. 184 185 \note This is only for the source files and for you as documenter. It will 186 not show up in the actual generated documentation! 187 188 \subsection formalrequirements_internal Internal documentation 189 190 It is possible that there is documentation for parts of the API that are 191 not (yet) part of the public API. It could either be that the documentation 192 is part of the public header file (usually hidden behind a namespace like 193 \c BPrivate), or it is part of a private header file. 194 195 In case you are in the situation where you need to store private API docs, 196 you should put the entirety of the documentation in a conditional block, 197 with the \c INTERNAL identifier. You open the block with the command 198 <tt>//! \\cond INTERNAL</tt> and end the block with the command 199 <tt>//! \\endcond INTERNAL</tt>. 200 201 There are two different cases where you must or could use these blocks: 202 203 1. For non-public API of a <em>public header file</em>, you must always 204 add the classes and other elements to the documentation (even if they) 205 are placeholders, and put them in the conditional block. 206 2. For parts of the non-public API that is in a <em>private header 207 file</em>, you could put the documentation in a conditional block. If 208 you choose to do so, you must document all elements in that header 209 file. 210 211 \section commands Doxygen Commands 212 213 This section describes all the Doxygen commands that will be used in the 214 Haiku API documentation. As a rule, Doxygen commands start with a backslash 215 (\\) and are followed by whitespace (such as a space or a newline), with the 216 exception of group markers; this is discussed in more detail later on. The 217 commands can be divided into several categories, which are described in the 218 following subsections. 219 220 \note This section does not discuss which commands you should actually use 221 in documentation. See the next section on \ref style for that. This 222 section merely explains the different groupings and syntaxes of 223 commands. 224 225 Most commands accept an argument. Arguments can be one of these three types: 226 - \<single_word\> - The argument is a single word. 227 - (until the end of the line) - The argument runs until the end of the line. 228 - {paragraph} - The argument runs for an entire paragraph. A paragraph is 229 ended by an empty line, or if another command that defines a \ref 230 commands_sections sections is found. Note that if you use commands that 231 work on a paragraph and you split it over multiple lines (because of the 232 maximum line width of 80 characters or because it looks better), you 233 will have to indent subsequent lines that belong to the paragraph with 234 two more spaces, making the total of four. This is to visually 235 distinguish paragraphs for other documenters. 236 237 \subsection commands_definitions Block Definitions 238 239 Because our API documentation is not done in the source, nor in the headers, 240 Doxygen needs to be helped with figuring out what the documentation in the 241 different blocks actually are about. That's why the first line in a 242 documentation block would be one of the following commands: 243 244 - \c \\class \<name\> \n 245 Tells Doxygen that the following section is going to be on the class as 246 specified by \a name. 247 - \c \\fn (function declaration) \n 248 This block is going to be about the function that corresponds to the 249 given declaration. Please note that the declaration is what you find in 250 the source file, so if class members are declared, the classname and the 251 scope operator, \c ::, are to be added as well. Modifiers such as \c 252 const should be included. 253 - \c \\var (variable declaration) \n 254 This block is going to be about the variable indicated by the 255 declaration. This means basically that data members of a class should 256 have the classname and the scope operator as well. 257 - \c \\typedef (typedef declaration) \n 258 This block is going to be about the typedef indicated by the 259 declaration. Copy the declaration exactly, including the leading \c 260 typedef keyword. 261 - \c \\struct \<name\> \n 262 Tells Doxygen the section is going to be on the \c struct indicated by 263 \a name. 264 - \c \\def \<name\> \n 265 This block is going to be about the \c \#define with the identifier \a 266 name. 267 - \c \\page \n 268 This block represents a page. See the section on \ref commands_pages for 269 detailed information on pages. 270 271 \subsection commands_sections Sections in Member Documentation 272 273 If you have a look at the output that Doxygen generates, you can see that 274 there are recurring sections in the documentation. Documentation that 275 belongs to a certain section should be placed after a command that marks the 276 start of that section. All the commands take a paragraph as answer. A 277 paragraph ends with a whitespace, or with a command that marks a new 278 section. Note that this list only shows the syntax of the commands. For the 279 semantics, have a look at the next section on style. In member documentation 280 you can use the following: 281 282 - \c \\brief {brief description} \n 283 This is the only \b mandatory section. Every member should have at least 284 a brief description. 285 - \c \\param \<parameter-name\> {parameter description} \n 286 This section describes a parameter with the name \a parameter-name. The 287 parameter name must match the function declaration, since Doxygen will 288 check if all the documented parameters exist. 289 - \c \\return {description of the return value} \n 290 This section describes the return value. This is a totally free form 291 paragraph, whereas \c \\retval has a more structured form. 292 - \c \\retval \<value\> {description} \n 293 This section describes the return value indicated by \a value. 294 - \c \\see {references} \n 295 This section contains references to other parts of the documentation. 296 297 There are also a number of things that can be used in pages and member 298 documentation. See the style section to find out the appropriate situations 299 in which to use them. 300 - \c \\note {text} 301 - \c \\attention {text} 302 - \c \\warning {text} 303 - \c \\remarks {text} 304 305 \subsection commands_markup Markup 306 307 Sometimes you might require certain text to have a special markup, to make 308 words stand out, but also if you want to have example code within the 309 documentation you'll need a special markup. Doxygen defines three types of 310 commands. There are commands that work on single words, commands that work 311 on longer phrases and commands that define blocks. Basically, the single 312 letter commands are commands that work on a the next word. If you need to 313 mark multiple words or sentences, use the HTML-style commands. Finally, for 314 blocks of code or blocks of text that need to be in "typewriter" font, use 315 the block commands. Have a look at the following listing: 316 317 - \c \\a \n 318 Use to refer to parameters or arguments in a running text, for example 319 when referring to parameters in method descriptions. 320 - <b>Bold text</b> 321 - For single words, use \c \\b. 322 - For multiple words, enclose between the \c \<b\> and \c \<\\b\> tags. 323 - <tt>Typewriter font</tt> \n 324 This can be used to refer to constants, or anything that needs to be in 325 a monospace, or typewriter, font. There are a few options 326 - \c \\c for single words. 327 - \c \<tt\> and \c \<\\tt\> for multiple words or phrases 328 - The commands \c \\verbatim and \c \\endverbatim. Everything between 329 these two commands will be put in a distinct block that stands out 330 from the rest of the text. 331 - The commands \c \\code and \c \\endcode do the same, but Doxygen will 332 parse the contents and try to mark up the code to make it look a 333 little bit nicer. 334 - <em>Emphasis</em> 335 - \c \\e for single words. 336 - \c \<em\> and \c \<\\em\> for phrases. 337 338 \subsection commands_pages Page Commands 339 340 Pages are a very special element of the documentation. They are not 341 associated with any kind of module, such as files or classes, and therefore, 342 since they're not members, some of the structuring commands won't work. 343 Important to know is that a page is the complete length of the block, so 344 dividing it up in subsections by starting new blocks will not work. Instead, 345 Doxygen provides some commands to structure text on a page. 346 347 First of all, you define a new page by using the \c \\page command. This 348 command takes two arguments: a \c \<name\> and <tt>(a title)</tt>. The name 349 is the internal identifier that can be used in linking between pages (see 350 \ref commands_miscellaneous for \c \\ref). After you've defined the block 351 to be a page, you can start writing the contents. 352 353 For more complicated pages, you might want to divide the page up in 354 sections. Use the \c \\section command to define a new section. It takes the 355 same arguments as \c \\page, namely the \c \<name\> and the 356 <tt>(title)</tt>. If you need a deeper hierarchy you may use \c \\subsection 357 and \c \\subsubsection, again, both with the same syntax. If you need to 358 distinguish between sections in sub-sub-sections, you are able to use 359 \c \\paragraph, which takes the same arguments. 360 361 \note Before and after each of the commands above, you need to have an empty 362 line so as to provide readability. It is not necessary to indent 363 sections and subsections more than the normal two spaces, as long as you 364 keep the section markers clear. 365 366 \warning If you are entering the realm of subsections and sub-subsections, 367 think about the nature of your page. Either it needs to be split up into 368 multiple pages, or what you're writing is too complex and would be 369 better off as a big tutorial on the Haiku website. 370 371 If you are creating multiple pages that are related, you will be able to 372 structure them in a tree by using the \c \\subpage command. This will rank 373 the different pages in a tree structure. It will put a link in the place of 374 the command, so you should place it at the top of the parent place and use 375 it as an index. 376 377 \subsection commands_grouping Member Grouping Commands 378 379 Doxygen makes it possible to group certain members together. It is used 380 in the BString class for example, where the members are grouped by what kind 381 of operation they perform, such as appending, finding, etc. Defining groups 382 is currently not as powerful as it could be, but if you use it inside 383 classes, you will be fine if you follow the instructions presented in 384 this section. 385 386 \note If you are looking on how to add classes to kits, see 387 \ref commands_miscellaneous and have a look at the \c \\ingroup command. 388 389 Groups of members are preceded by a block that describes what the group is 390 about. You are required to give each group of members at least a name. Have 391 a look at the example: 392 393\verbatim 394/*! 395 \name Appending Methods 396 397 These methods append things to the object. 398*/ 399 400 401//! \@{ 402 403 404... methods ... 405 406 407//! \@} 408 409\endverbatim 410 411 The block preceding the block opening marker, <tt>//! \@{</tt>, contains a 412 \c \\name command and a paragraph that gives a description. The header 413 block can be as long or short as you want, but please don't make it too 414 long. See the \ref style section on how to effectively write group headers. 415 The members that you want to belong to the group are between the group 416 opening and closing markers. 417 418 \note Group headers don't have a \c \\brief description. 419 420 \subsection commands_miscellaneous Miscellaneous Commands 421 422 There are some commands that don't fit into the categories above, but that 423 you will end up using every now and then. This section will describe those 424 commands. 425 426 The first one is \c \\n. This commands sort of belongs to the category of 427 markup commands. It basically forces a newline. Because Doxygen parses 428 paragraphs as a single contiguous entity, it's not possible to mark up the 429 text using carriage returns in the documentation. \c \\n forces a newline in 430 the output. So in HTML it will be translated into a \c \<br\\\>. 431 432 Sometimes there are some parts of the API that you don't want to be visible. 433 Since Doxygen extracts all the public and protected members from a class, 434 and virtually every member from a file, you might want to force it to hide 435 certain things. If so, use the \c \\internal command. If you place this just 436 after the block marker, the command will be hidden from documentation. Any 437 further documentation or remarks you put inside the block will not be 438 visible in the final documentation. 439 440 Images can be a valuable addition to documentation. To include ones you 441 made, use the \c \\image command. It has the following prototype: 442 <tt>\\image \<format\> \<file\></tt>. The format is currently fixed at 443 \c html. The file refers to the filename relative to the location of the 444 documentation file. Any images you want to add should be in the same 445 location as the dox file, so only the file name will suffice. 446 447 Modules are defined in the main book, and you can add classes to them by 448 using the \c \\ingroup command. This commands adds the class to the module 449 and groups it on a separate page. At this moment, the group handling has yet 450 to be finalized. For now, add the classes to the kit they belong in. In the 451 future this might change. 452 453 Finally, it is a good idea to link between parts of the documentation. There 454 are two commands for that. The first one is \c \\ref, which enable you to 455 refer to pages, sections, etc. that you created yourself. The second one is 456 \c \\link which refers to members. The first one is takes one word as an 457 argument, the name of the section, and it inserts a link with the name of 458 the title. \c \\link is more complex. It should always be accompanied by \c 459 \\endlink. The first word between the two commands is the object that is 460 referred to, and the rest is the link text. 461 462 \section style Writing Guidelines 463 464 This final section will present guidelines for the actual writing of the 465 documentation. Both the structure of the documentation, which sections to 466 use when, and the style of the writing will be discussed. Before diverging 467 into the requirements for file and class descriptions, member descriptions 468 and pages, there are some general remarks that apply to all types of 469 documentation. 470 471 First of all, everything you write should be in <em>proper English 472 sentences</em>. Spelling, grammar, punctuation, make sure you adhere to the 473 standards. It also means the following: 474 - It means that every sentence should at least have a 475 subject and a verb (unless it's an imperative statement). 476 - Also use the proper terminology. Remember, you are dealing with C++ 477 here, which means you should use the right names. So use \b method 478 instead of function, and data member instead of variable (where 479 appropriate). 480 - Avoid in-formalism. Avoid constructs like 'if you want to 481 disconnect the object', but rather use 'to disconnect the object'. Avoid 482 familiarizes, or jokes. 483 484 \remarks It isn't the goal to create dry, legal-style documentation. Just 485 try to find a balance. Read through documentation that's already been 486 approved to get a hint of what you should be aiming for. 487 \remarks If you are having a problem with phrasing certain things, put it 488 down in such a way that it says everything it needs to. A proofreader 489 might then be able to rephrase it to a better style. 490 491 Throughout the documentation you might want to provide hints, warnings or 492 remarks that might interrupt the flow of the text, or that need to visually 493 stand out from the rest. Doxygen provides commands for paragraphs that 494 display remarks, warnings, notes and points of attention. You can use these 495 commands in case you meet one or more of the following requirements: 496 - The point is for a specific audience, such as beginners in the Haiku API. 497 Notes on what to read first, or mistakes that may be made by beginners 498 will not be for the entire audience, and such should be separated. These 499 kinds of notes should be at the end of blocks. 500 - The point needs to visually stand out. This is especially the case with 501 remarks, but could also apply for other types. 502 - The point is not completely relevant to the text and therefore should be 503 separated so that it doesn't interrupt the main flow. 504 505 This listing shows which one to use for which situation: 506 - \c \\attention 507 - Used when the developer is bound to make a mistake, when the API is 508 ambiguous. The difference between this and a warning is that 509 warnings warn about things that are the developers fault, and 510 attention blocks warn about things that might go wrong 511 because of the way the API is structured. 512 - Used to warn for abuse of the API that might be caused by the way the 513 internals of the system are structured. 514 - \c \\warning 515 - Used to warn developers about using the API in a certain way. Warnings 516 apply especially to new developers that aren't completely familiar 517 with the API and that might want to abuse it. For example, the 518 thread safety of BString requires a warning. 519 - \c \\note 520 - Used to place references to other documentation that might not be 521 directly related to the text. For example, BLooper will have a 522 direct reference to BHandler in the class description, but 523 BMessenger will be mentioned in a note because it does not directly 524 influence the use of the class. 525 - Can also be used for useful hints or notes that somehow need to stand 526 out from the rest of the text. 527 - \c \\remarks 528 - Remarks are small notes that would interrupt the flow of the text. For 529 example, if you in a text ignore a certain condition that is so 530 extremely rare and uncommon, you can put a remark at the end of the 531 text to tell that you have been lying. 532 - Remarks interact with the text whereas notes add something unmentioned 533 to it. 534 535 \subsection style_files File Descriptions 536 537 The design of Doxygen makes it very file oriented, and this might come off 538 as inconvenient. At the moment, how to actually group the documentation is 539 still under debate, but it does not change the requirement that a header 540 needs to be documented before the members of that header can be documented. 541 As such, the first documentation block in your \c dox file will be the block 542 that describes the header. Examples: 543 544\verbatim 545/*! 546 \file String.h 547 \brief Defines the BString class and global operators and functions for 548 handling strings. 549*/ 550 551 552/*! 553 \file SupportDefs.h 554 \brief Defines basic types and definitions for the Haiku API. 555*/ 556\endverbatim 557 558 The first statement defines what the block is about, namely the header file. 559 The second element is the \c \\brief remark on what it contains. The first 560 file defines the BString class and some global operators. You can see that 561 reflected in the description. SupportDefs.h does not define classes, but 562 rather a range of different functions and defines, so the text refers to 563 that. 564 565 \remarks \\brief documentation for files is about what it \e implements, as 566 header files are passive (whereas members and functions are active). 567 Thus, use the third person form of the verb. 568 569 \subsection style_classes Class Descriptions 570 571 Classes are the basic building blocks in the Haiku API and as such have 572 extensive documentation. This section will go over the actual class 573 description. This section will present a list of items you should think 574 about when writing the class description. This doesn't mean you'll have 575 to include every item, it merely serves as a guiding principle that helps 576 organise your thoughts. Have a look at the list: 577 578 -# The \c \\brief description is \b obligatory. This description describes 579 what it is. For example, BDataIO: "Abstract interface for objects that 580 provide read and write access to data." Note that this description is 581 not a full sentence, but it does end with a period. 582 -# One or more paragraphs that give a broad overview of what the class can 583 do. Describe things like what it works on, when you want to use it, what 584 advantage it might give over other directly related alternatives. Also 585 describe if a class is made to be derived from, and if so, how. Make 586 sure that a developer in the first few paragraphs can judge if what he 587 wants to do can be done with this class. 588 -# One or more paragraphs that show how this class ties in with the rest 589 of the kit or the API. What objects does it work with, how it interacts 590 with the servers, etcetera. 591 -# One or more paragraphs that give a concrete example or use case. Keep it 592 tidy and self contained. If you use code examples, make sure your 593 examples adhere to Haiku's coding guidelines. Remember, an example can 594 illustrate better than a few paragraphs of text. 595 -# End with a list of references to other classes, functions, pages, etc. 596 that might be of interest to the reader. 597 598 When documenting classes, don't be to exhaustive. Avoid becoming a tutorial 599 or a complete guide. This documentation is for reference only. If you want 600 to enlighten the reader on bigger subjects, consider writing a separate 601 documentation page that connects the different points you want to make. 602 603 Also, you don't have to put in any groupings of members in class 604 descriptions. If you want to do that, physically divide the members up in 605 groups. Look at the \ref commands_grouping for the actual commands, and at 606 \ref style_groups for help on writing group headers. 607 608 \subsection style_members Members and Functions 609 610 Members and functions share the same basic Doxygen syntax, and they can be 611 documented in a similar way. That's why this section deals with them 612 together. Documenting members is probably the main thing you'll do when 613 writing the actual documentation. There are some guidelines as to how, but 614 the actual implementation probably differs per class. Keep the following 615 points in mind: 616 617 -# To repeat a very important fact, the first line is a \c \\fn line. This 618 line needs to match the declaration, which is in the source file. This 619 means that for members, also the class name and the scope indicator (::) 620 should be present. Also note that this line doesn't have to adhere to 621 the 80 column width limit. 622 -# The first command is always the \c \\brief command. Give a short and 623 clear description. The description starts with a capital letter and ends 624 with a dot. Don't write the description saying what the method does, 625 like "Starts the timer", but rather as what it will do: "Start the 626 timer." -# If the brief description doesn't cover all of what the method 627 or function does, then you can add a few paragraphs that explain it in 628 more depth. Don't be too verbose, and use an example to illustrate 629 points. Point out any potential misunderstandings or problems you expect 630 developers to have, but don't repeat the class documentation too much. 631 -# You are obliged to then document all the parameters. Use the \c \\param 632 command for that. For the description, use a short phrase such as "The 633 offset (zero based) where to begin the move." Note the capital and the 634 dot. 635 -# If the function is non-void, then you'll have to specify what it will 636 return. In case of fixed values, have a look at \c \\retval. You'll use 637 this one when the return type is a bool or a status_t. In case of 638 something else, use \c \\return. You can also combine these two. For 639 example, a method that returns a length (positive) or an error code 640 (negative). 641 -# Use \c \\see if you have any references to other methods, classes or 642 global functions. At least document all the overloaded methods. Also add 643 methods that do the opposite of this method, or methods that are 644 intimately related. 645 646 In case of overloaded members, you'll need to make a decision. If you need 647 to copy too much information, you might resort to putting it in one 648 paragraph with the text "This is an overloaded member function, and differs 649 from \<name\> only by the type of parameter it takes." That will keep the 650 copying down and will point developers right to the place where they can get 651 more documentation. 652 653 Again, like class descriptions, you'll have to find a good middle-ground 654 between too much information, and too little. Again, write for the broadest 655 audience possible, and resort to notes and warnings for specialised 656 audiences. 657 658 \subsection style_variables Enumerations, Variables and Defines 659 660 This section helps you document (member) variables and defines that define 661 constants, as well as enumerations and their values. If you need to document 662 a \c \#define macro that takes arguments, have a look at \ref style_members 663 664 The \c \\brief description of all these types follow a similar structure. 665 They are a short phrase that mention what the variable contains. Example: 666 667\verbatim 668/*! 669 \var char* BString::fPrivateData 670 \brief BString's storage for data. 671 672 This member is deprecated and might even become \c private in future 673 releases. 674 675 If you are planning to derive from this object and you want to manipulate 676 the raw string data, please have a look at LockBuffer() and UnlockBuffer(). 677*/ 678\endverbatim 679 680 The variables you are going to encounter are either \c public or 681 \c protected member variables, or global variables that have a certain 682 significance. In the case of member variables, you'll need to document what 683 they mean and how the developer should manipulate them. If the class is one 684 that is meant to be derived from, make sure that in the description of the 685 variable you mention how it interacts with the others, and how the developer 686 should make sure that the internal coherence of the data and code members of 687 the inherited class is maintained. 688 689 Global variables will mostly be constants. If so, document what they stand 690 for and what they might be used for, as well as which classes and functions 691 depend on that constant. If the variable is meant to be changed by the 692 developer, explain what values are valid and which functions and classes 693 depend on this variable. 694 695 Defines are usually used as message constants. Give a short description of 696 what the message constant stands for, and where it might be send from and 697 where it might be received. 698 699 Enumerations can either be anonymous or named. In case of the latter, you 700 can give a description of the enumeration in a documentation block that 701 starts with an \c \\enum command, followed by the name of the enumeration. 702 If the enumeration is within the scope of a class, prepend the classname and 703 the scope indicator. In case of an anonymous enum, you can only document the 704 individual members (which you should do for the named enumerations as well), 705 which can be done within code blocks that start with the \c \\var command. 706 Doxygen will know that it's an enumeration value, don't worry about mixups. 707 If the enumeration value is within a class, prepend the classname and scope 708 indicator. Give a short description of the value, which methods react to 709 it, where it might be used, etcetera. Don't go as far as to copy information 710 too much. For example, if you use an enumeration in only one class and you 711 document the possible values there, then don't do that again for the 712 enumeration documentation: rather just refer to it. That sort of 713 documentation belongs to the class description, not to the enumeration. 714 715 \subsection style_groups Groups 716 717 If you subdivide members of classes into groups, you have the ability to 718 apply some general information that will be listed above the listing of the 719 members in that group. See the section \ref commands_grouping on how to 720 define groups. This section is on what to put in the header block. 721 722 First of all, it's probably a good idea to give your group a name. This name 723 will be printed as a title and will enhance the clarity of what the group 724 contains. If you put the \c \\name command as the first command of a group, 725 the rest of the words on that line will be used as the title. You should 726 choose simple titles of no more than three words. 727 728 It's possible to add one or two paragraphs of information. These paragraphs 729 should contain some quick notes on which of the members in that group to use 730 for what purpose. See it as a quick subdivision that a developer could use 731 as a guide to see which method he actually wants to use. Don't go on 732 describing the methods in detail though, that's what the member 733 documentation is about. Have a look at the example: 734 735\verbatim 736/*! 737 \name Comparison Methods 738 739 There are two different comparison methods. First of all there is the whole 740 range of operators that return a boolean value, secondly there are methods 741 that return an integer value, both case sensitive and case insensitive. 742 743 There are also global comparison operators and global compare functions. 744 You might need these in case you have a sort routine that takes a generic 745 comparison function, such as BList::SortItems(). 746 747 See the String.h documentation file to see the specifics, as they are 748 basically the same as implemented in this class. 749*/ 750\endverbatim 751 752 Straight, to the point, gives no more information than necessary. Divides 753 the members up into two groups and refers to other functions the developer 754 might be looking for. The hard limit is two (short) paragraphs. Using more 755 will not improve clarity. 756*/ 757