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 license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10     @class wxConfigBase
  11
  12     wxConfigBase defines the basic interface of all config classes. It can not
  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 Win32 or text-based config files under Unix (or
  20     even Windows 3.1 .INI files if you're really unlucky). To make writing the
  21     portable code even easier, wxWidgets provides a typedef wxConfig which is
  22     mapped onto the native wxConfigBase implementation on the given platform:
  23     i.e. wxRegConfig under Win32 and wxFileConfig otherwise.
  24
  25     See @ref overview_config for a description of all features of this class.
  26
  27     It is highly recommended to use static functions Get() and/or Set(), so
  28     please have a look at them.
  29
  30     Related Include Files:
  31
  32     @li @c <wx/config.h>   - Let wxWidgets choose a wxConfig class for your
  33                              platform.
  34     @li @c <wx/confbase.h> - Base config class.
  35     @li @c <wx/fileconf.h> - wxFileConfig class.
  36     @li @c <wx/msw/regconf.h> - wxRegConfig class, see also wxRegKey.
  37
  38
  39     @section configbase_example Example
  40
  41     Here is how you would typically use this class:
  42
  43     @code
  44     // using wxConfig instead of writing wxFileConfig or wxRegConfig enhances
  45     // portability of the code
  46     wxConfig *config = new wxConfig("MyAppName");
  47
  48     wxString str;
  49     if ( config->Read("LastPrompt", &str) ) {
  50         // last prompt was found in the config file/registry and its value is
  51         // now in str
  52         // ...
  53     }
  54     else {
  55         // no last prompt...
  56     }
  57
  58     // another example: using default values and the full path instead of just
  59     // key name: if the key is not found , the value 17 is returned
  60     long value = config->ReadLong("/LastRun/CalculatedValues/MaxValue", 17);
  61
  62     // at the end of the program we would save everything back
  63     config->Write("LastPrompt", str);
  64     config->Write("/LastRun/CalculatedValues/MaxValue", value);
  65
  66     // the changes will be written back automatically
  67     delete config;
  68     @endcode
  69
  70     This basic example, of course, doesn't show all wxConfig features, such as
  71     enumerating, testing for existence and deleting the entries and groups of
  72     entries in the config file, its abilities to automatically store the
  73     default values or expand the environment variables on the fly. However, the
  74     main idea is that using this class is easy and that it should normally do
  75     what you expect it to.
  76
  77     @note In the documentation of this class, the words "config file" also mean
  78           "registry hive" for wxRegConfig and, generally speaking, might mean
  79           any physical storage where a wxConfigBase-derived class stores its
  80           data.
  81
  82
  83     @section configbase_static Static Functions
  84
  85     The static functions provided deal with the "default" config object.
  86     Although its usage is not at all mandatory it may be convenient to use a
  87     global config object instead of creating and deleting the local config
  88     objects each time you need one (especially because creating a wxFileConfig
  89     object might be a time consuming operation). In this case, you may create
  90     this global config object in the very start of the program and Set() it as
  91     the default. Then, from anywhere in your program, you may access it using
  92     the Get() function. This global wxConfig object will be deleted by
  93     wxWidgets automatically if it exists. Note that this implies that if you do
  94     delete this object yourself (usually in wxApp::OnExit()) you must use
  95     Set(@NULL) to prevent wxWidgets from deleting it the second time.
  96
  97     As it happens, you may even further simplify the procedure described above:
  98     you may forget about calling Set(). When Get() is called and there is no
  99     current object, it will create one using Create() function. To disable this
 100     behaviour DontCreateOnDemand() is provided.
 101
 102     @note You should use either Set() or Get() because wxWidgets library itself
 103           would take advantage of it and could save various information in it.
 104           For example wxFontMapper or Unix version of wxFileDialog have the
 105           ability to use wxConfig class.
 106
 107
 108     @section configbase_paths Path Management
 109
 110     As explained in the @ref overview_config "config overview", the config
 111     classes support a file system-like hierarchy of keys (files) and groups
 112     (directories). As in the file system case, to specify a key in the config
 113     class you must use a path to it. Config classes also support the notion of
 114     the current group, which makes it possible to use the relative paths. To
 115     clarify all this, here is an example (it is only for the sake of
 116     demonstration, it doesn't do anything sensible!):
 117
 118     @code
 119     wxConfig *config = new wxConfig("FooBarApp");
 120
 121     // right now the current path is '/'
 122     conf->Write("RootEntry", 1);
 123
 124     // go to some other place: if the group(s) don't exist, they will be created
 125     conf->SetPath("/Group/Subgroup");
 126
 127     // create an entry in subgroup
 128     conf->Write("SubgroupEntry", 3);
 129
 130     // '..' is understood
 131     conf->Write("../GroupEntry", 2);
 132     conf->SetPath("..");
 133
 134     wxASSERT( conf->ReadLong("Subgroup/SubgroupEntry", 0) == 3 );
 135
 136     // use absolute path: it is allowed, too
 137     wxASSERT( conf->ReadLong("/RootEntry", 0) == 1 );
 138     @endcode
 139
 140     It is highly recommended that you restore the path to its old value on
 141     function exit:
 142
 143     @code
 144     void foo(wxConfigBase *config)
 145     {
 146         wxString strOldPath = config->GetPath();
 147
 148         config->SetPath("/Foo/Data");
 149         // ...
 150
 151         config->SetPath(strOldPath);
 152     }
 153     @endcode
 154
 155     Otherwise the assert in the following example will surely fail (we suppose
 156     here that the foo() function is the same as above except that it doesn’t
 157     save and restore the path):
 158
 159     @code
 160     void bar(wxConfigBase *config)
 161     {
 162         config->Write("Test", 17);
 163
 164         foo(config);
 165
 166         // we're reading "/Foo/Data/Test" here! -1 will probably be returned...
 167         wxASSERT( config->ReadLong("Test", -1) == 17 );
 168     }
 169     @endcode
 170
 171     Finally, the path separator in wxConfigBase and derived classes is always
 172     "/", regardless of the platform (i.e. it is not "\\" under Windows).
 173
 174
 175     @section configbase_enumeration Enumeration
 176
 177     The enumeration functions allow you to enumerate all entries and groups in
 178     the config file. All functions here return @false when there are no more
 179     items.
 180
 181     You must pass the same index to GetNext() and GetFirst() (don't modify it).
 182     Please note that it is not the index of the current item (you will have
 183     some great surprises with wxRegConfig if you assume this) and you shouldn't
 184     even look at it: it is just a "cookie" which stores the state of the
 185     enumeration. It can't be stored inside the class because it would prevent
 186     you from running several enumerations simultaneously, that's why you must
 187     pass it explicitly.
 188
 189     Having said all this, enumerating the config entries/groups is very simple:
 190
 191     @code
 192     wxConfigBase *config = ...;
 193     wxArrayString aNames;
 194
 195     // enumeration variables
 196     wxString str;
 197     long dummy;
 198
 199     // first enum all entries
 200     bool bCont = config->GetFirstEntry(str, dummy);
 201     while ( bCont ) {
 202         aNames.Add(str);
 203
 204         bCont = GetConfig()->GetNextEntry(str, dummy);
 205     }
 206
 207     // ... we have all entry names in aNames...
 208
 209     // now all groups...
 210     bCont = GetConfig()->GetFirstGroup(str, dummy);
 211     while ( bCont ) {
 212         aNames.Add(str);
 213
 214         bCont = GetConfig()->GetNextGroup(str, dummy);
 215     }
 216
 217     // ... we have all group (and entry) names in aNames...
 218     @endcode
 219
 220     There are also functions to get the number of entries/subgroups without
 221     actually enumerating them, but you will probably never need them.
 222
 223
 224     @section configbase_keyaccess Key Access
 225
 226     The key access functions are the core of wxConfigBase class: they allow you
 227     to read and write config file data. All Read() functions take a default
 228     value which will be returned if the specified key is not found in the
 229     config file.
 230
 231     Currently, supported types of data are: wxString, @c long, @c double,
 232     @c bool, wxColour and any other types for which the functions
 233     wxToString() and wxFromString() are defined.
 234
 235     Try not to read long values into string variables and vice versa:
 236     although it just might work with wxFileConfig, you will get a system
 237     error with wxRegConfig because in the Windows registry the different
 238     types of entries are indeed used.
 239
 240     Final remark: the @a szKey parameter for all these functions can
 241     contain an arbitrary path (either relative or absolute), not just the
 242     key name.
 243
 244     @beginWxPythonOnly
 245     In place of a single overloaded method name, wxPython implements the
 246     following methods:
 247     - Read(key, default="") - Returns a string.
 248     - ReadInt(key, default=0) - Returns an integer.
 249     - ReadFloat(key, default=0.0) - Returns a floating point number.
 250     - ReadBool(key, default=0) - Returns a boolean.
 251     - Write(key, value) - Writes a string.
 252     - WriteInt(key, value) - Writes an int.
 253     - WriteFloat(key, value) - Writes a floating point number.
 254     @endWxPythonOnly
 255
 256
 257     @library{wxbase}
 258     @category{misc}
 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 wxCONFIG_USE_LOCAL_FILE and wxCONFIG_USE_GLOBAL_FILE.
 285             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             wxCONFIG_USE_GLOBAL_FILE is used, then settings are read from the
 289             global config file and if 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, thie GLOBAL flag refers to HKLM key while LOCAL
 296             one is for the usual HKCU one.
 297             @n For wxFileConfig you can also add 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             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 localFilename is provided.
 307             wxCONFIG_USE_SUBDIR is new since wxWidgets version 2.8.2.
 308             @n For wxFileConfig, you can also add
 309             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 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 wxCONFIG_USE_NO_ESCAPE_CHARACTERS style is used, it is 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
 334     /**
 335         Empty but ensures that dtor of all derived classes is virtual.
 336     */
 337     virtual ~wxConfigBase();
 338
 339
 340     /**
 341         @name Path Management
 342
 343         See @ref configbase_paths
 344     */
 345     //@{
 346
 347     /**
 348         Retrieve the current path (always as absolute path).
 349     */
 350     const wxString GetPath() const;
 351
 352     /**
 353         Set current path: if the first character is '/', it is the absolute
 354         path, otherwise it is a relative path. '..' is supported. If @a strPath
 355         doesn't exist it is created.
 356     */
 357     void SetPath(const wxString& strPath);
 358
 359     //@}
 360
 361
 362     /**
 363         @name Enumeration
 364
 365         See @ref configbase_enumeration
 366     */
 367     //@{
 368
 369     /**
 370         Gets the first entry.
 371
 372         @beginWxPythonOnly
 373         The wxPython version of this method returns a 3-tuple consisting of the
 374         continue flag, the value string, and the index for the next call.
 375         @endWxPythonOnly
 376     */
 377     bool GetFirstEntry(wxString& str, long& index) const;
 378
 379     /**
 380         Gets the first group.
 381
 382         @beginWxPythonOnly
 383         The wxPython version of this method returns a 3-tuple consisting of the
 384         continue flag, the value string, and the index for the next call.
 385         @endWxPythonOnly
 386     */
 387     bool GetFirstGroup(wxString& str, long& index) const;
 388
 389     /**
 390         Gets the next entry.
 391
 392         @beginWxPythonOnly
 393         The wxPython version of this method returns a 3-tuple consisting of the
 394         continue flag, the value string, and the index for the next call.
 395         @endWxPythonOnly
 396     */
 397     bool GetNextEntry(wxString& str, long& index) const;
 398
 399     /**
 400         Gets the next group.
 401
 402         @beginWxPythonOnly
 403         The wxPython version of this method returns a 3-tuple consisting of the
 404         continue flag, the value string, and the index for the next call.
 405         @endWxPythonOnly
 406     */
 407     bool GetNextGroup(wxString& str, long& index) const;
 408
 409     /**
 410         Get number of entries in the current group.
 411     */
 412     uint GetNumberOfEntries(bool bRecursive = false) const;
 413
 414     /**
 415         Get number of entries/subgroups in the current group, with or without
 416         its subgroups.
 417     */
 418     uint GetNumberOfGroups(bool bRecursive = false) const;
 419
 420     //@}
 421
 422
 423     enum EntryType
 424     {
 425         Type_Unknown,
 426         Type_String,
 427         Type_Boolean,
 428         Type_Integer,
 429         Type_Float
 430     };
 431
 432     /**
 433         @name Tests of Existence
 434     */
 435     //@{
 436
 437     /**
 438         @return @true if either a group or an entry with a given name exists.
 439     */
 440     bool Exists(wxString& strName) const;
 441
 442     /**
 443         Returns the type of the given entry or @e Unknown if the entry doesn't
 444         exist. This function should be used to decide which version of Read()
 445         should be used because some of wxConfig implementations will complain
 446         about type mismatch otherwise: e.g., an attempt to read a string value
 447         from an integer key with wxRegConfig will fail.
 448     */
 449     wxConfigBase::EntryType GetEntryType(const wxString& name) const;
 450
 451     /**
 452         @return @true if the entry by this name exists.
 453     */
 454     bool HasEntry(wxString& strName) const;
 455
 456     /**
 457         @return @true if the group by this name exists.
 458     */
 459     bool HasGroup(const wxString& strName) const;
 460
 461     //@}
 462
 463
 464     /**
 465         @name Miscellaneous Functions
 466     */
 467     //@{
 468
 469     /**
 470         Returns the application name.
 471     */
 472     wxString GetAppName() const;
 473
 474     /**
 475         Returns the vendor name.
 476     */
 477     wxString GetVendorName() const;
 478
 479     //@}
 480
 481
 482     /**
 483         @name Key Access
 484
 485         See @ref configbase_keyaccess
 486     */
 487     //@{
 488
 489     /**
 490         Permanently writes all changes (otherwise, they're only written from
 491         object's destructor).
 492     */
 493     bool Flush(bool bCurrentOnly = false);
 494
 495     /**
 496         Read a string from the key, returning @true if the value was read. If
 497         the key was not found, @a str is not changed.
 498     */
 499     bool Read(const wxString& key, wxString* str) const;
 500     /**
 501         Read a string from the key. The default value is returned if the key
 502         was not found.
 503
 504         @return @true if value was really read, @false if the default was used.
 505     */
 506     const bool Read(const wxString& key, wxString* str,
 507                       const wxString& defaultVal) const;
 508     /**
 509         Another version of Read(), returning the string value directly.
 510     */
 511     const wxString Read(const wxString& key,
 512                          const wxString& defaultVal) const;
 513     /**
 514         Reads a long value, returning @true if the value was found. If the
 515         value was not found, @a l is not changed.
 516     */
 517     const bool Read(const wxString& key, long* l) const;
 518     /**
 519         Reads a long value, returning @true if the value was found. If the
 520         value was not found, @a defaultVal is used instead.
 521     */
 522     const bool Read(const wxString& key, long* l,
 523                     long defaultVal) const;
 524     /**
 525         Reads a double value, returning @true if the value was found. If the
 526         value was not found, @a d is not changed.
 527     */
 528     const bool Read(const wxString& key, double* d) const;
 529     /**
 530         Reads a double value, returning @true if the value was found. If the
 531         value was not found, @a defaultVal is used instead.
 532     */
 533     const bool Read(const wxString& key, double* d,
 534                      double defaultVal) const;
 535     /**
 536         Reads a bool value, returning @true if the value was found. If the
 537         value was not found, @a b is not changed.
 538     */
 539     const bool Read(const wxString& key, bool* b) const;
 540     /**
 541         Reads a bool value, returning @true if the value was found. If the
 542         value was not found, @a defaultVal is used instead.
 543     */
 544     const bool Read(const wxString& key, bool* d,
 545                      bool defaultVal) const;
 546     /**
 547         Reads a binary block, returning @true if the value was found. If the
 548         value was not found, @a buf is not changed.
 549     */
 550     const bool Read(const wxString& key, wxMemoryBuffer* buf) const;
 551     /**
 552         Reads a value of type T, for which function wxFromString() is defined,
 553         returning @true if the value was found. If the value was not found,
 554         @a value is not changed.
 555     */
 556     const bool Read(const wxString& key, T* value) const;
 557     /**
 558         Reads a value of type T, for which function wxFromString() is defined,
 559         returning @true if the value was found. If the value was not found,
 560         @a defaultVal is used instead.
 561     */
 562     const bool Read(const wxString& key, T* value,
 563                      const T& defaultVal) const;
 564
 565     /**
 566         Reads a bool value from the key and returns it. @a defaultVal is
 567         returned if the key is not found.
 568     */
 569     long ReadBool(const wxString& key, bool defaultVal) const;
 570
 571     /**
 572         Reads a double value from the key and returns it. @a defaultVal is
 573         returned if the key is not found.
 574     */
 575     long ReadDouble(const wxString& key, double defaultVal) const;
 576
 577     /**
 578         Reads a long value from the key and returns it. @a defaultVal is
 579         returned if the key is not found.
 580     */
 581     long ReadLong(const wxString& key, long defaultVal) const;
 582
 583     /**
 584         Reads a value of type T (for which the function wxFromString() must be
 585         defined) from the key and returns it. @a defaultVal is returned if the
 586         key is not found.
 587     */
 588     T ReadObject(const wxString& key, T const& defaultVal) const;
 589
 590     /**
 591         Writes the wxString value to the config file and returns @true on
 592         success.
 593     */
 594     bool Write(const wxString& key, const wxString& value);
 595     /**
 596         Writes the long value to the config file and returns @true on success.
 597     */
 598     bool Write(const wxString& key, long value);
 599     /**
 600         Writes the double value to the config file and returns @true on
 601         success.
 602     */
 603     bool Write(const wxString& key, double value);
 604     /**
 605         Writes the bool value to the config file and returns @true on success.
 606     */
 607     bool Write(const wxString& key, bool value);
 608     /**
 609         Writes the wxMemoryBuffer value to the config file and returns @true on
 610         success.
 611     */
 612     bool Write(const wxString& key, const wxMemoryBuffer& buf);
 613     /**
 614         Writes the specified value to the config file and returns @true on
 615         success. The function wxToString() must be defined for type @e T.
 616     */
 617     bool Write(const wxString& key, T const& buf);
 618
 619     //@}
 620
 621
 622     /**
 623         @name Rename Entries/Groups
 624
 625         These functions allow renaming entries or subgroups of the current
 626         group. They will return @false on error, typically because either the
 627         entry/group with the original name doesn't exist, because the
 628         entry/group with the new name already exists or because the function is
 629         not supported in this wxConfig implementation.
 630     */
 631     //@{
 632
 633     /**
 634         Renames an entry in the current group. The entries names (both the old
 635         and the new one) shouldn't contain backslashes, i.e. only simple names
 636         and not arbitrary paths are accepted by this function.
 637
 638         @return @false if @a oldName doesn't exist or if @a newName already
 639                 exists.
 640     */
 641     bool RenameEntry(const wxString& oldName, const wxString& newName);
 642
 643     /**
 644         Renames a subgroup of the current group. The subgroup names (both the
 645         old and the new one) shouldn't contain backslashes, i.e. only simple
 646         names and not arbitrary paths are accepted by this function.
 647
 648         @return @false if @a oldName doesn't exist or if @a newName already
 649                 exists.
 650     */
 651     bool RenameGroup(const wxString& oldName, const wxString& newName);
 652
 653     //@}
 654
 655
 656     /**
 657         @name Delete Entries/Groups
 658
 659         These functions delete entries and/or groups of entries from the config
 660         file. DeleteAll() is especially useful if you want to erase all traces
 661         of your program presence: for example, when you uninstall it.
 662     */
 663     //@{
 664
 665     /**
 666         Delete the whole underlying object (disk file, registry key, ...).
 667         Primarly for use by uninstallation routine.
 668     */
 669     bool DeleteAll();
 670
 671     /**
 672         Deletes the specified entry and the group it belongs to if it was the
 673         last key in it and the second parameter is @true.
 674     */
 675     bool DeleteEntry(const wxString& key,
 676                      bool bDeleteGroupIfEmpty = true);
 677
 678     /**
 679         Delete the group (with all subgroups). If the current path is under the
 680         group being deleted it is changed to its deepest still existing
 681         component. E.g. if the current path is @c "/A/B/C/D" and the group @c C
 682         is deleted, the path becomes @c "/A/B".
 683     */
 684     bool DeleteGroup(const wxString& key);
 685
 686     //@}
 687
 688
 689     /**
 690         @name Options
 691
 692         Some aspects of wxConfigBase behaviour can be changed during run-time.
 693         The first of them is the expansion of environment variables in the
 694         string values read from the config file: for example, if you have the
 695         following in your config file:
 696
 697         @code
 698         # config file for my program
 699         UserData = $HOME/data
 700
 701         # the following syntax is valud only under Windows
 702         UserData = %windir%\\data.dat
 703         @endcode
 704
 705         The call to Read("UserData") will return something like
 706         @c "/home/zeitlin/data" on linux for example.
 707
 708         Although this feature is very useful, it may be annoying if you read a
 709         value which containts '$' or '%' symbols (% is used for environment
 710         variables expansion under Windows) which are not used for environment
 711         variable expansion. In this situation you may call
 712         SetExpandEnvVars(@false) just before reading this value and
 713         SetExpandEnvVars(@true) just after. Another solution would be to prefix
 714         the offending symbols with a backslash.
 715     */
 716     //@{
 717
 718     /**
 719         Returns @true if we are expanding environment variables in key values.
 720     */
 721     bool IsExpandingEnvVars() const;
 722
 723     /**
 724         Returns @true if we are writing defaults back to the config file.
 725     */
 726     bool IsRecordingDefaults() const;
 727
 728     /**
 729         Determine whether we wish to expand environment variables in key
 730         values.
 731     */
 732     void SetExpandEnvVars(bool bDoIt = true);
 733
 734     /**
 735         Sets whether defaults are recorded to the config file whenever an
 736         attempt to read the value which is not present in it is done.
 737
 738         If on (default is off) all default values for the settings used by the
 739         program are written back to the config file. This allows the user to
 740         see what config options may be changed and is probably useful only for
 741         wxFileConfig.
 742     */
 743     void SetRecordDefaults(bool bDoIt = true);
 744
 745     //@}
 746
 747
 748     /**
 749         Create a new config object: this function will create the "best"
 750         implementation of wxConfig available for the current platform, see
 751         comments near the definition of wxCONFIG_WIN32_NATIVE for details. It
 752         returns the created object and also sets it as the current one.
 753     */
 754     static wxConfigBase* Create();
 755
 756     /**
 757         Calling this function will prevent @e Get() from automatically creating
 758         a new config object if the current one is @NULL. It might be useful to
 759         call it near the program end to prevent "accidental" creation of a new
 760         config object.
 761     */
 762     static void DontCreateOnDemand();
 763
 764     /**
 765         Get the current config object. If there is no current object and
 766         @a CreateOnDemand is @true, this creates one (using Create()) unless
 767         DontCreateOnDemand() was called previously.
 768     */
 769     static wxConfigBase* Get(bool CreateOnDemand = true);
 770
 771     /**
 772         Sets the config object as the current one, returns the pointer to the
 773         previous current object (both the parameter and returned value may be
 774         @NULL).
 775     */
 776     static wxConfigBase* Set(wxConfigBase* pConfig);
 777 };
 778