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