interface/wx/config.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        config.h
   3 // Purpose:     interface of wxConfigBase
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows licence
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9
  10 // Flags for constructor style parameter
  11 enum
  12 {
  13     wxCONFIG_USE_LOCAL_FILE = 1,
  14     wxCONFIG_USE_GLOBAL_FILE = 2,
  15     wxCONFIG_USE_RELATIVE_PATH = 4,
  16     wxCONFIG_USE_NO_ESCAPE_CHARACTERS = 8,
  17     wxCONFIG_USE_SUBDIR = 16
  18 };
  19
  20
  21 /**
  22     @class wxConfigBase
  23
  24     wxConfigBase defines the basic interface of all config classes. It cannot
  25     be used by itself (it is an abstract base class) and you will always use
  26     one of its derivations: wxFileConfig, wxRegConfig or any other.
  27
  28     However, usually you don't even need to know the precise nature of the
  29     class you're working with but you would just use the wxConfigBase methods.
  30     This allows you to write the same code regardless of whether you're working
  31     with the registry under Windows or text-based config files under Unix.
  32     To make writing the portable code even easier, wxWidgets provides a typedef
  33     wxConfig which is mapped onto the native wxConfigBase implementation on the
  34     given platform: i.e. wxRegConfig under Windows and wxFileConfig otherwise.
  35
  36     See @ref overview_config for a description of all features of this class.
  37
  38     It is highly recommended to use static functions Get() and/or Set(), so
  39     please have a look at them.
  40
  41     Related Include Files:
  42
  43     @li @c <wx/config.h>   - Let wxWidgets choose a wxConfig class for your
  44                              platform.
  45     @li @c <wx/confbase.h> - Base config class.
  46     @li @c <wx/fileconf.h> - wxFileConfig class.
  47     @li @c <wx/msw/regconf.h> - wxRegConfig class, see also wxRegKey.
  48
  49
  50     @section configbase_example Example
  51
  52     Here is how you would typically use this class:
  53
  54     @code
  55     // using wxConfig instead of writing wxFileConfig or wxRegConfig enhances
  56     // portability of the code
  57     wxConfig *config = new wxConfig("MyAppName");
  58
  59     wxString str;
  60     if ( config->Read("LastPrompt", &str) ) {
  61         // last prompt was found in the config file/registry and its value is
  62         // now in str
  63         // ...
  64     }
  65     else {
  66         // no last prompt...
  67     }
  68
  69     // another example: using default values and the full path instead of just
  70     // key name: if the key is not found , the value 17 is returned
  71     long value = config->ReadLong("/LastRun/CalculatedValues/MaxValue", 17);
  72
  73     // at the end of the program we would save everything back
  74     config->Write("LastPrompt", str);
  75     config->Write("/LastRun/CalculatedValues/MaxValue", value);
  76
  77     // the changes will be written back automatically
  78     delete config;
  79     @endcode
  80
  81     This basic example, of course, doesn't show all wxConfig features, such as
  82     enumerating, testing for existence and deleting the entries and groups of
  83     entries in the config file, its abilities to automatically store the
  84     default values or expand the environment variables on the fly. However, the
  85     main idea is that using this class is easy and that it should normally do
  86     what you expect it to.
  87
  88     @note In the documentation of this class, the words "config file" also mean
  89           "registry hive" for wxRegConfig and, generally speaking, might mean
  90           any physical storage where a wxConfigBase-derived class stores its
  91           data.
  92
  93
  94     @section configbase_static Static Functions
  95
  96     The static functions provided deal with the "default" config object.
  97     Although its usage is not at all mandatory it may be convenient to use a
  98     global config object instead of creating and deleting the local config
  99     objects each time you need one (especially because creating a wxFileConfig
 100     object might be a time consuming operation). In this case, you may create
 101     this global config object in the very start of the program and Set() it as
 102     the default. Then, from anywhere in your program, you may access it using
 103     the Get() function. This global wxConfig object will be deleted by
 104     wxWidgets automatically if it exists. Note that this implies that if you do
 105     delete this object yourself (usually in wxApp::OnExit()) you must use
 106     Set(@NULL) to prevent wxWidgets from deleting it the second time.
 107
 108     As it happens, you may even further simplify the procedure described above:
 109     you may forget about calling Set(). When Get() is called and there is no
 110     current object, it will create one using Create() function. To disable this
 111     behaviour DontCreateOnDemand() is provided.
 112
 113     @note You should use either Set() or Get() because wxWidgets library itself
 114           would take advantage of it and could save various information in it.
 115           For example wxFontMapper or Unix version of wxFileDialog have the
 116           ability to use wxConfig class.
 117
 118
 119     @section configbase_paths Path Management
 120
 121     As explained in the @ref overview_config "config overview", the config
 122     classes support a file system-like hierarchy of keys (files) and groups
 123     (directories). As in the file system case, to specify a key in the config
 124     class you must use a path to it. Config classes also support the notion of
 125     the current group, which makes it possible to use the relative paths. To
 126     clarify all this, here is an example (it is only for the sake of
 127     demonstration, it doesn't do anything sensible!):
 128
 129     @code
 130     wxConfig *config = new wxConfig("FooBarApp");
 131
 132     // right now the current path is '/'
 133     conf->Write("RootEntry", 1);
 134
 135     // go to some other place: if the group(s) don't exist, they will be created
 136     conf->SetPath("/Group/Subgroup");
 137
 138     // create an entry in subgroup
 139     conf->Write("SubgroupEntry", 3);
 140
 141     // '..' is understood
 142     conf->Write("../GroupEntry", 2);
 143     conf->SetPath("..");
 144
 145     wxASSERT( conf->ReadLong("Subgroup/SubgroupEntry", 0) == 3 );
 146
 147     // use absolute path: it is allowed, too
 148     wxASSERT( conf->ReadLong("/RootEntry", 0) == 1 );
 149     @endcode
 150
 151     It is highly recommended that you restore the path to its old value on
 152     function exit:
 153
 154     @code
 155     void foo(wxConfigBase *config)
 156     {
 157         wxString strOldPath = config->GetPath();
 158
 159         config->SetPath("/Foo/Data");
 160         // ...
 161
 162         config->SetPath(strOldPath);
 163     }
 164     @endcode
 165
 166     Otherwise the assert in the following example will surely fail (we suppose
 167     here that the foo() function is the same as above except that it doesn’t
 168     save and restore the path):
 169
 170     @code
 171     void bar(wxConfigBase *config)
 172     {
 173         config->Write("Test", 17);
 174
 175         foo(config);
 176
 177         // we're reading "/Foo/Data/Test" here! -1 will probably be returned...
 178         wxASSERT( config->ReadLong("Test", -1) == 17 );
 179     }
 180     @endcode
 181
 182     Finally, the path separator in wxConfigBase and derived classes is always
 183     "/", regardless of the platform (i.e. it is not "\\" under Windows).
 184
 185
 186     @section configbase_enumeration Enumeration
 187
 188     The enumeration functions allow you to enumerate all entries and groups in
 189     the config file. All functions here return @false when there are no more
 190     items.
 191
 192     You must pass the same index to GetNext() and GetFirst() (don't modify it).
 193     Please note that it is not the index of the current item (you will have
 194     some great surprises with wxRegConfig if you assume this) and you shouldn't
 195     even look at it: it is just a "cookie" which stores the state of the
 196     enumeration. It can't be stored inside the class because it would prevent
 197     you from running several enumerations simultaneously, that's why you must
 198     pass it explicitly.
 199
 200     Having said all this, enumerating the config entries/groups is very simple:
 201
 202     @code
 203     wxConfigBase *config = ...;
 204     wxArrayString aNames;
 205
 206     // enumeration variables
 207     wxString str;
 208     long dummy;
 209
 210     // first enum all entries
 211     bool bCont = config->GetFirstEntry(str, dummy);
 212     while ( bCont ) {
 213         aNames.Add(str);
 214
 215         bCont = GetConfig()->GetNextEntry(str, dummy);
 216     }
 217
 218     // ... we have all entry names in aNames...
 219
 220     // now all groups...
 221     bCont = GetConfig()->GetFirstGroup(str, dummy);
 222     while ( bCont ) {
 223         aNames.Add(str);
 224
 225         bCont = GetConfig()->GetNextGroup(str, dummy);
 226     }
 227
 228     // ... we have all group (and entry) names in aNames...
 229     @endcode
 230
 231     There are also functions to get the number of entries/subgroups without
 232     actually enumerating them, but you will probably never need them.
 233
 234
 235     @section configbase_keyaccess Key Access
 236
 237     The key access functions are the core of wxConfigBase class: they allow you
 238     to read and write config file data. All Read() functions take a default
 239     value which will be returned if the specified key is not found in the
 240     config file.
 241
 242     Currently, supported types of data are: wxString, @c long, @c double,
 243     @c bool, wxColour and any other types for which the functions
 244     wxToString() and wxFromString() are defined.
 245
 246     Try not to read long values into string variables and vice versa:
 247     although it just might work with wxFileConfig, you will get a system
 248     error with wxRegConfig because in the Windows registry the different
 249     types of entries are indeed used.
 250
 251     Final remark: the @a szKey parameter for all these functions can
 252     contain an arbitrary path (either relative or absolute), not just the
 253     key name.
 254
 255     @library{wxbase}
 256     @category{cfg}
 257
 258     @see wxConfigPathChanger
 259 */
 260 class wxConfigBase : public wxObject
 261 {
 262 public:
 263     /**
 264         This is the default and only constructor of the wxConfigBase class, and
 265         derived classes.
 266
 267         @param appName
 268             The application name. If this is empty, the class will normally use
 269             wxApp::GetAppName() to set it. The application name is used in the
 270             registry key on Windows, and can be used to deduce the local
 271             filename parameter if that is missing.
 272         @param vendorName
 273             The vendor name. If this is empty, it is assumed that no vendor
 274             name is wanted, if this is optional for the current config class.
 275             The vendor name is appended to the application name for
 276             wxRegConfig.
 277         @param localFilename
 278             Some config classes require a local filename. If this is not
 279             present, but required, the application name will be used instead.
 280         @param globalFilename
 281             Some config classes require a global filename. If this is not
 282             present, but required, the application name will be used instead.
 283         @param style
 284             Can be one of @c wxCONFIG_USE_LOCAL_FILE and @c wxCONFIG_USE_GLOBAL_FILE.
 285             @n The style interpretation depends on the config class and is ignored
 286             by some implementations. For wxFileConfig, these styles determine
 287             whether a local or global config file is created or used: if
 288             @c wxCONFIG_USE_GLOBAL_FILE is used, then settings are read from the
 289             global config file and if @c wxCONFIG_USE_LOCAL_FILE is used, settings
 290             are read from and written to local config file (if they are both
 291             set, global file is read first, then local file, overwriting global
 292             settings). If the flag is present but the parameter is empty, the
 293             parameter will be set to a default. If the parameter is present but
 294             the style flag not, the relevant flag will be added to the style.
 295             For wxRegConfig, the GLOBAL flag refers to the @c HKLM key while LOCAL
 296             one is for the usual @c HKCU one.
 297             @n For wxFileConfig you can also add @c wxCONFIG_USE_RELATIVE_PATH by
 298             logically or'ing it to either of the _FILE options to tell
 299             wxFileConfig to use relative instead of absolute paths.
 300             @n On non-VMS Unix systems, the default local configuration file is
 301             "~/.appname". However, this path may be also used as user data
 302             directory (see wxStandardPaths::GetUserDataDir()) if the
 303             application has several data files. In this case
 304             @c wxCONFIG_USE_SUBDIR flag, which changes the default local
 305             configuration file to "~/.appname/appname" should be used. Notice
 306             that this flag is ignored if @a localFilename is provided.
 307             @c wxCONFIG_USE_SUBDIR is new since wxWidgets version 2.8.2.
 308             @n For wxFileConfig, you can also add
 309             @c wxCONFIG_USE_NO_ESCAPE_CHARACTERS which will turn off character
 310             escaping for the values of entries stored in the config file: for
 311             example a foo key with some backslash characters will be stored as
 312             "foo=C:\mydir" instead of the usual storage of "foo=C:\\mydir".
 313             @n The @c wxCONFIG_USE_NO_ESCAPE_CHARACTERS style can be helpful if your
 314             config file must be read or written to by a non-wxWidgets program
 315             (which might not understand the escape characters). Note, however,
 316             that if @c wxCONFIG_USE_NO_ESCAPE_CHARACTERS style is used, it is
 317             now your application's responsibility to ensure that there is no
 318             newline or other illegal characters in a value, before writing that
 319             value to the file.
 320         @param conv
 321             This parameter is only used by wxFileConfig when compiled in
 322             Unicode mode. It specifies the encoding in which the configuration
 323             file is written.
 324
 325         @remarks By default, environment variable expansion is on and recording
 326                  defaults is off.
 327     */
 328     wxConfigBase(const wxString& appName = wxEmptyString,
 329                  const wxString& vendorName = wxEmptyString,
 330                  const wxString& localFilename = wxEmptyString,
 331                  const wxString& globalFilename = wxEmptyString,
 332                  long style = 0,
 333                  const wxMBConv& conv = wxConvAuto());
 334
 335     /**
 336         Empty but ensures that dtor of all derived classes is virtual.
 337     */
 338     virtual ~wxConfigBase();
 339
 340
 341     /**
 342         @name Path Management
 343
 344         See @ref configbase_paths
 345     */
 346     //@{
 347
 348     /**
 349         Retrieve the current path (always as absolute path).
 350     */
 351     virtual const wxString& GetPath() const = 0;
 352
 353     /**
 354         Set current path: if the first character is '/', it is the absolute
 355         path, otherwise it is a relative path. '..' is supported. If @a strPath
 356         doesn't exist, it is created.
 357
 358         @see wxConfigPathChanger
 359     */
 360     virtual void SetPath(const wxString& strPath) = 0;
 361
 362     //@}
 363
 364
 365     /**
 366         @name Enumeration
 367
 368         See @ref configbase_enumeration
 369     */
 370     //@{
 371
 372     /**
 373         Gets the first entry.
 374
 375         @beginWxPerlOnly
 376         In wxPerl this method takes no parameters and returns a 3-element
 377         list (continue_flag, string, index_for_getnextentry).
 378         @endWxPerlOnly
 379     */
 380     virtual bool GetFirstEntry(wxString& str, long& index) const = 0;
 381
 382     /**
 383         Gets the first group.
 384
 385         @beginWxPerlOnly
 386         In wxPerl this method takes no parameters and returns a 3-element
 387         list (continue_flag, string, index_for_getnextentry).
 388         @endWxPerlOnly
 389     */
 390     virtual bool GetFirstGroup(wxString& str, long& index) const = 0;
 391
 392     /**
 393         Gets the next entry.
 394
 395         @beginWxPerlOnly
 396         In wxPerl this method only takes the @a index parameter and
 397         returns a 3-element list (continue_flag, string,
 398         index_for_getnextentry).
 399         @endWxPerlOnly
 400     */
 401     virtual bool GetNextEntry(wxString& str, long& index) const = 0;
 402
 403     /**
 404         Gets the next group.
 405
 406         @beginWxPerlOnly
 407         In wxPerl this method only takes the @a index parameter and
 408         returns a 3-element list (continue_flag, string,
 409         index_for_getnextentry).
 410         @endWxPerlOnly
 411     */
 412     virtual bool GetNextGroup(wxString& str, long& index) const = 0;
 413
 414     /**
 415         Get number of entries in the current group.
 416     */
 417     virtual size_t GetNumberOfEntries(bool bRecursive = false) const = 0;
 418
 419     /**
 420         Get number of entries/subgroups in the current group, with or without
 421         its subgroups.
 422     */
 423     virtual size_t GetNumberOfGroups(bool bRecursive = false) const = 0;
 424
 425     //@}
 426
 427
 428     enum EntryType
 429     {
 430         Type_Unknown,
 431         Type_String,
 432         Type_Boolean,
 433         Type_Integer,
 434         Type_Float
 435     };
 436
 437     /**
 438         @name Tests of Existence
 439     */
 440     //@{
 441
 442     /**
 443         @return @true if either a group or an entry with a given name exists.
 444     */
 445     bool Exists(const wxString& strName) const;
 446
 447     /**
 448         Returns the type of the given entry or @e Unknown if the entry doesn't
 449         exist. This function should be used to decide which version of Read()
 450         should be used because some of wxConfig implementations will complain
 451         about type mismatch otherwise: e.g., an attempt to read a string value
 452         from an integer key with wxRegConfig will fail.
 453     */
 454     virtual wxConfigBase::EntryType GetEntryType(const wxString& name) const;
 455
 456     /**
 457         @return @true if the entry by this name exists.
 458     */
 459     virtual bool HasEntry(const wxString& strName) const = 0;
 460
 461     /**
 462         @return @true if the group by this name exists.
 463     */
 464     virtual bool HasGroup(const wxString& strName) const = 0;
 465
 466     //@}
 467
 468
 469     /**
 470         @name Miscellaneous Functions
 471     */
 472     //@{
 473
 474     /**
 475         Returns the application name.
 476     */
 477     wxString GetAppName() const;
 478
 479     /**
 480         Returns the vendor name.
 481     */
 482     wxString GetVendorName() const;
 483
 484     //@}
 485
 486
 487     /**
 488         @name Key Access
 489
 490         See @ref configbase_keyaccess
 491     */
 492     //@{
 493
 494     /**
 495         Permanently writes all changes (otherwise, they're only written from
 496         object's destructor).
 497     */
 498     virtual bool Flush(bool bCurrentOnly = false) = 0;
 499
 500     /**
 501         Read a string from the key, returning @true if the value was read. If
 502         the key was not found, @a str is not changed.
 503
 504         @beginWxPerlOnly
 505         Not supported by wxPerl.
 506         @endWxPerlOnly
 507     */
 508     bool Read(const wxString& key, wxString* str) const;
 509     /**
 510         Read a string from the key. The default value is returned if the key
 511         was not found.
 512
 513         @return @true if value was really read, @false if the default was used.
 514
 515         @beginWxPerlOnly
 516         Not supported by wxPerl.
 517         @endWxPerlOnly
 518     */
 519     bool Read(const wxString& key, wxString* str,
 520               const wxString& defaultVal) const;
 521     /**
 522         Another version of Read(), returning the string value directly.
 523
 524         @beginWxPerlOnly
 525         In wxPerl, this can be called as:
 526         - Read(key): returns the empty string if no key is found
 527         - Read(key, default): returns the default value if no key is found
 528         @endWxPerlOnly
 529     */
 530     const wxString Read(const wxString& key,
 531                         const wxString& defaultVal) const;
 532     /**
 533         Reads a long value, returning @true if the value was found. If the
 534         value was not found, @a l is not changed.
 535
 536         @beginWxPerlOnly
 537         Not supported by wxPerl.
 538         @endWxPerlOnly
 539     */
 540     bool Read(const wxString& key, long* l) const;
 541     /**
 542         Reads a long value, returning @true if the value was found. If the
 543         value was not found, @a defaultVal is used instead.
 544
 545         @beginWxPerlOnly
 546         In wxPerl, this can be called as:
 547         - ReadInt(key): returns the 0 if no key is found
 548         - ReadInt(key, default): returns the default value if no key is found
 549         @endWxPerlOnly
 550     */
 551     bool Read(const wxString& key, long* l,
 552               long defaultVal) const;
 553     /**
 554         Reads a double value, returning @true if the value was found. If the
 555         value was not found, @a d is not changed.
 556
 557         @beginWxPerlOnly
 558         Not supported by wxPerl.
 559         @endWxPerlOnly
 560     */
 561     bool Read(const wxString& key, double* d) const;
 562     /**
 563         Reads a double value, returning @true if the value was found. If the
 564         value was not found, @a defaultVal is used instead.
 565
 566         @beginWxPerlOnly
 567         In wxPerl, this can be called as:
 568         - ReadFloat(key): returns the 0.0 if no key is found
 569         - ReadFloat(key, default): returns the default value if no key is found
 570         @endWxPerlOnly
 571     */
 572     bool Read(const wxString& key, double* d,
 573                      double defaultVal) const;
 574
 575     /**
 576         Reads a float value, returning @true if the value was found.
 577
 578         If the value was not found, @a f is not changed.
 579
 580         Notice that the value is read as a double but must be in a valid range
 581         for floats for the function to return @true.
 582
 583         @since 2.9.1
 584
 585         @beginWxPerlOnly
 586         Not supported by wxPerl.
 587         @endWxPerlOnly
 588     */
 589     bool Read(const wxString& key, float* f) const;
 590     /**
 591         Reads a float value, returning @true if the value was found.
 592
 593         If the value was not found, @a defaultVal is used instead.
 594
 595         Notice that the value is read as a double but must be in a valid range
 596         for floats for the function to return @true.
 597
 598         @since 2.9.1
 599
 600         @beginWxPerlOnly
 601         Not supported by wxPerl.
 602         @endWxPerlOnly
 603     */
 604     bool Read(const wxString& key, float* f, float defaultVal) const;
 605
 606     /**
 607         Reads a boolean value, returning @true if the value was found. If the
 608         value was not found, @a b is not changed.
 609
 610         @since 2.9.1
 611
 612         @beginWxPerlOnly
 613         Not supported by wxPerl.
 614         @endWxPerlOnly
 615     */
 616     bool Read(const wxString& key, bool* b) const;
 617     /**
 618         Reads a boolean value, returning @true if the value was found. If the
 619         value was not found, @a defaultVal is used instead.
 620
 621         @beginWxPerlOnly
 622         In wxPerl, this can be called as:
 623         - ReadBool(key): returns false if no key is found
 624         - ReadBool(key, default): returns the default value if no key is found
 625         @endWxPerlOnly
 626     */
 627     bool Read(const wxString& key, bool* d,
 628               bool defaultVal) const;
 629     /**
 630         Reads a binary block, returning @true if the value was found. If the
 631         value was not found, @a buf is not changed.
 632     */
 633     bool Read(const wxString& key, wxMemoryBuffer* buf) const;
 634     /**
 635         Reads a value of type T, for which function wxFromString() is defined,
 636         returning @true if the value was found. If the value was not found,
 637         @a value is not changed.
 638     */
 639     bool Read(const wxString& key, T* value) const;
 640     /**
 641         Reads a value of type T, for which function wxFromString() is defined,
 642         returning @true if the value was found. If the value was not found,
 643         @a defaultVal is used instead.
 644     */
 645     bool Read(const wxString& key, T* value,
 646               const T& defaultVal) const;
 647
 648     /**
 649         Reads a bool value from the key and returns it. @a defaultVal is
 650         returned if the key is not found.
 651     */
 652     bool ReadBool(const wxString& key, bool defaultVal) const;
 653
 654     /**
 655         Reads a double value from the key and returns it. @a defaultVal is
 656         returned if the key is not found.
 657     */
 658     double ReadDouble(const wxString& key, double defaultVal) const;
 659
 660     /**
 661         Reads a long value from the key and returns it. @a defaultVal is
 662         returned if the key is not found.
 663     */
 664     long ReadLong(const wxString& key, long defaultVal) const;
 665
 666     /**
 667         Reads a value of type T (for which the function wxFromString() must be
 668         defined) from the key and returns it. @a defaultVal is returned if the
 669         key is not found.
 670     */
 671     T ReadObject(const wxString& key, T const& defaultVal) const;
 672
 673     /**
 674         Writes the wxString value to the config file and returns @true on
 675         success.
 676     */
 677     bool Write(const wxString& key, const wxString& value);
 678     /**
 679         Writes the long value to the config file and returns @true on success.
 680     */
 681     bool Write(const wxString& key, long value);
 682     /**
 683         Writes the double value to the config file and returns @true on
 684         success.
 685
 686         Notice that if floating point numbers are saved as strings (as is the
 687         case with the configuration files used by wxFileConfig), this function
 688         uses the C locale for writing out the number, i.e. it will always use a
 689         period as the decimal separator, irrespectively of the current locale.
 690         This behaviour is new since wxWidgets 2.9.1 as the current locale was
 691         used before, but the change should be transparent because both C and
 692         current locales are tried when reading the numbers back.
 693     */
 694     bool Write(const wxString& key, double value);
 695     /**
 696         Writes the bool value to the config file and returns @true on success.
 697     */
 698     bool Write(const wxString& key, bool value);
 699     /**
 700         Writes the wxMemoryBuffer value to the config file and returns @true on
 701         success.
 702     */
 703     bool Write(const wxString& key, const wxMemoryBuffer& buf);
 704     /**
 705         Writes the specified value to the config file and returns @true on
 706         success. The function wxToString() must be defined for type @e T.
 707     */
 708     bool Write(const wxString& key, T const& buf);
 709
 710     //@}
 711
 712
 713     /**
 714         @name Rename Entries/Groups
 715
 716         These functions allow renaming entries or subgroups of the current
 717         group. They will return @false on error, typically because either the
 718         entry/group with the original name doesn't exist, because the
 719         entry/group with the new name already exists or because the function is
 720         not supported in this wxConfig implementation.
 721     */
 722     //@{
 723
 724     /**
 725         Renames an entry in the current group. The entries names (both the old
 726         and the new one) shouldn't contain backslashes, i.e. only simple names
 727         and not arbitrary paths are accepted by this function.
 728
 729         @return @false if @a oldName doesn't exist or if @a newName already
 730                 exists.
 731     */
 732     virtual bool RenameEntry(const wxString& oldName,
 733                              const wxString& newName) = 0;
 734
 735     /**
 736         Renames a subgroup of the current group. The subgroup names (both the
 737         old and the new one) shouldn't contain backslashes, i.e. only simple
 738         names and not arbitrary paths are accepted by this function.
 739
 740         @return @false if @a oldName doesn't exist or if @a newName already
 741                 exists.
 742     */
 743     virtual bool RenameGroup(const wxString& oldName,
 744                              const wxString& newName) = 0;
 745
 746     //@}
 747
 748
 749     /**
 750         @name Delete Entries/Groups
 751
 752         These functions delete entries and/or groups of entries from the config
 753         file. DeleteAll() is especially useful if you want to erase all traces
 754         of your program presence: for example, when you uninstall it.
 755     */
 756     //@{
 757
 758     /**
 759         Delete the whole underlying object (disk file, registry key, ...).
 760         Primarily for use by uninstallation routine.
 761     */
 762     virtual bool DeleteAll() = 0;
 763
 764     /**
 765         Deletes the specified entry and the group it belongs to if it was the
 766         last key in it and the second parameter is @true.
 767     */
 768     virtual bool DeleteEntry(const wxString& key,
 769                              bool bDeleteGroupIfEmpty = true) = 0;
 770
 771     /**
 772         Delete the group (with all subgroups). If the current path is under the
 773         group being deleted it is changed to its deepest still existing
 774         component. E.g. if the current path is @c "/A/B/C/D" and the group @c C
 775         is deleted, the path becomes @c "/A/B".
 776     */
 777     virtual bool DeleteGroup(const wxString& key) = 0;
 778
 779     //@}
 780
 781
 782     /**
 783         @name Options
 784
 785         Some aspects of wxConfigBase behaviour can be changed during run-time.
 786         The first of them is the expansion of environment variables in the
 787         string values read from the config file: for example, if you have the
 788         following in your config file:
 789
 790         @code
 791         # config file for my program
 792         UserData = $HOME/data
 793
 794         # the following syntax is valud only under Windows
 795         UserData = %windir%\\data.dat
 796         @endcode
 797
 798         The call to Read("UserData") will return something like
 799         @c "/home/zeitlin/data" on linux for example.
 800
 801         Although this feature is very useful, it may be annoying if you read a
 802         value which containts '$' or '%' symbols (% is used for environment
 803         variables expansion under Windows) which are not used for environment
 804         variable expansion. In this situation you may call
 805         SetExpandEnvVars(@false) just before reading this value and
 806         SetExpandEnvVars(@true) just after. Another solution would be to prefix
 807         the offending symbols with a backslash.
 808     */
 809     //@{
 810
 811     /**
 812         Returns @true if we are expanding environment variables in key values.
 813     */
 814     bool IsExpandingEnvVars() const;
 815
 816     /**
 817         Returns @true if we are writing defaults back to the config file.
 818     */
 819     bool IsRecordingDefaults() const;
 820
 821     /**
 822         Determine whether we wish to expand environment variables in key
 823         values.
 824     */
 825     void SetExpandEnvVars(bool bDoIt = true);
 826
 827     /**
 828         Sets whether defaults are recorded to the config file whenever an
 829         attempt to read the value which is not present in it is done.
 830
 831         If on (default is off) all default values for the settings used by the
 832         program are written back to the config file. This allows the user to
 833         see what config options may be changed and is probably useful only for
 834         wxFileConfig.
 835     */
 836     void SetRecordDefaults(bool bDoIt = true);
 837
 838     //@}
 839
 840
 841     /**
 842         Create a new config object and sets it as the current one.
 843
 844         This function will create the most appropriate implementation of
 845         wxConfig available for the current platform. By default this means that
 846         the system registry will be used for storing the configuration
 847         information under MSW and a file under the user home directory (see
 848         wxStandardPaths::GetUserConfigDir()) elsewhere.
 849
 850         If you prefer to use the configuration files everywhere, you can define
 851         @c wxUSE_CONFIG_NATIVE to 0 when compiling wxWidgets. Or you can simply
 852         always create wxFileConfig explicitly.
 853
 854         Finally, if you want to create a custom wxConfig subclass you may
 855         change this function behaviour by overriding wxAppTraits::CreateConfig()
 856         to create it. An example when this could be useful could be an
 857         application which could be installed either normally (in which case the
 858         default behaviour of using wxRegConfig is appropriate) or in a
 859         "portable" way in which case a wxFileConfig with a file in the program
 860         directory would be used and the choice would be done in CreateConfig()
 861         at run-time.
 862     */
 863     static wxConfigBase* Create();
 864
 865     /**
 866         Calling this function will prevent @e Get() from automatically creating
 867         a new config object if the current one is @NULL. It might be useful to
 868         call it near the program end to prevent "accidental" creation of a new
 869         config object.
 870     */
 871     static void DontCreateOnDemand();
 872
 873     /**
 874         Get the current config object. If there is no current object and
 875         @a CreateOnDemand is @true, this creates one (using Create()) unless
 876         DontCreateOnDemand() was called previously.
 877     */
 878     static wxConfigBase* Get(bool CreateOnDemand = true);
 879
 880     /**
 881         Sets the config object as the current one, returns the pointer to the
 882         previous current object (both the parameter and returned value may be
 883         @NULL).
 884     */
 885     static wxConfigBase* Set(wxConfigBase* pConfig);
 886 };
 887
 888
 889 /**
 890     @class wxConfigPathChanger
 891
 892     A handy little class which changes the current path in a wxConfig object and restores it in dtor.
 893     Declaring a local variable of this type, it's possible to work in a specific directory
 894     and ensure that the path is automatically restored when the function returns.
 895
 896     For example:
 897     @code
 898     // this function loads somes settings from the given wxConfig object;
 899     // the path selected inside it is left unchanged
 900     bool LoadMySettings(wxConfigBase* cfg)
 901     {
 902         wxConfigPathChanger changer(cfg, "/Foo/Data/SomeString");
 903         wxString str;
 904         if ( !config->Read("SomeString", &str) ) {
 905             wxLogError("Couldn't read SomeString!");
 906             return false;
 907                 // NOTE: without wxConfigPathChanger it would be easy to forget to
 908                 //       set the old path back into the wxConfig object before this return!
 909         }
 910
 911         // do something useful with SomeString...
 912
 913         return true;    // again: wxConfigPathChanger dtor will restore the original wxConfig path
 914     }
 915     @endcode
 916
 917     @library{wxbase}
 918     @category{cfg}
 919 */
 920 class wxConfigPathChanger
 921 {
 922 public:
 923
 924     /**
 925         Changes the path of the given wxConfigBase object so that the key @a strEntry is accessible
 926         (for read or write).
 927
 928         In other words, the ctor uses wxConfigBase::SetPath() with everything which precedes the
 929         last slash of @a strEntry, so that:
 930         @code
 931         wxConfigPathChanger(wxConfigBase::Get(), "/MyProgram/SomeKeyName");
 932         @endcode
 933         has the same effect of:
 934         @code
 935         wxConfigPathChanger(wxConfigBase::Get(), "/MyProgram/");
 936         @endcode
 937     */
 938     wxConfigPathChanger(const wxConfigBase *pContainer, const wxString& strEntry);
 939
 940     /**
 941         Restores the path selected, inside the wxConfig object passed to the ctor, to the path which was
 942         selected when the wxConfigPathChanger ctor was called.
 943     */
 944     ~wxConfigPathChanger();
 945
 946     /**
 947         Returns the name of the key which was passed to the ctor.
 948         The "name" is just anything which follows the last slash of the string given to the ctor.
 949     */
 950     const wxString& Name() const;
 951
 952     /**
 953         This method must be called if the original path inside the wxConfig object
 954         (i.e. the current path at the moment of creation of this wxConfigPathChanger object)
 955         could have been deleted, thus preventing wxConfigPathChanger from restoring the not
 956         existing (any more) path.
 957
 958         If the original path doesn't exist any more, the path will be restored to
 959         the deepest still existing component of the old path.
 960     */
 961     void UpdateIfDeleted();
 962 };
 963