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     @beginWxPythonOnly
 244     In place of a single overloaded method name, wxPython implements the
 245     following methods:
 246     - Read(key, default="") - Returns a string.
 247     - ReadInt(key, default=0) - Returns an integer.
 248     - ReadFloat(key, default=0.0) - Returns a floating point number.
 249     - ReadBool(key, default=0) - Returns a boolean.
 250     - Write(key, value) - Writes a string.
 251     - WriteInt(key, value) - Writes an int.
 252     - WriteFloat(key, value) - Writes a floating point number.
 253     @endWxPythonOnly
 254
 255
 256     @library{wxbase}
 257     @category{cfg}
 258
 259     @see wxConfigPathChanger
 260 */
 261 class wxConfigBase : public wxObject
 262 {
 263 public:
 264     /**
 265         This is the default and only constructor of the wxConfigBase class, and
 266         derived classes.
 267
 268         @param appName
 269             The application name. If this is empty, the class will normally use
 270             wxApp::GetAppName() to set it. The application name is used in the
 271             registry key on Windows, and can be used to deduce the local
 272             filename parameter if that is missing.
 273         @param vendorName
 274             The vendor name. If this is empty, it is assumed that no vendor
 275             name is wanted, if this is optional for the current config class.
 276             The vendor name is appended to the application name for
 277             wxRegConfig.
 278         @param localFilename
 279             Some config classes require a local filename. If this is not
 280             present, but required, the application name will be used instead.
 281         @param globalFilename
 282             Some config classes require a global filename. If this is not
 283             present, but required, the application name will be used instead.
 284         @param style
 285             Can be one of @c wxCONFIG_USE_LOCAL_FILE and @c wxCONFIG_USE_GLOBAL_FILE.
 286             @n The style interpretation depends on the config class and is ignored
 287             by some implementations. For wxFileConfig, these styles determine
 288             whether a local or global config file is created or used: if
 289             @c wxCONFIG_USE_GLOBAL_FILE is used, then settings are read from the
 290             global config file and if @c wxCONFIG_USE_LOCAL_FILE is used, settings
 291             are read from and written to local config file (if they are both
 292             set, global file is read first, then local file, overwriting global
 293             settings). If the flag is present but the parameter is empty, the
 294             parameter will be set to a default. If the parameter is present but
 295             the style flag not, the relevant flag will be added to the style.
 296             For wxRegConfig, the GLOBAL flag refers to the @c HKLM key while LOCAL
 297             one is for the usual @c HKCU one.
 298             @n For wxFileConfig you can also add @c wxCONFIG_USE_RELATIVE_PATH by
 299             logically or'ing it to either of the _FILE options to tell
 300             wxFileConfig to use relative instead of absolute paths.
 301             @n On non-VMS Unix systems, the default local configuration file is
 302             "~/.appname". However, this path may be also used as user data
 303             directory (see wxStandardPaths::GetUserDataDir()) if the
 304             application has several data files. In this case
 305             @c wxCONFIG_USE_SUBDIR flag, which changes the default local
 306             configuration file to "~/.appname/appname" should be used. Notice
 307             that this flag is ignored if @a localFilename is provided.
 308             @c wxCONFIG_USE_SUBDIR is new since wxWidgets version 2.8.2.
 309             @n For wxFileConfig, you can also add
 310             @c wxCONFIG_USE_NO_ESCAPE_CHARACTERS which will turn off character
 311             escaping for the values of entries stored in the config file: for
 312             example a foo key with some backslash characters will be stored as
 313             "foo=C:\mydir" instead of the usual storage of "foo=C:\\mydir".
 314             @n The @c wxCONFIG_USE_NO_ESCAPE_CHARACTERS style can be helpful if your
 315             config file must be read or written to by a non-wxWidgets program
 316             (which might not understand the escape characters). Note, however,
 317             that if @c wxCONFIG_USE_NO_ESCAPE_CHARACTERS style is used, it is
 318             now your application's responsibility to ensure that there is no
 319             newline or other illegal characters in a value, before writing that
 320             value to the file.
 321         @param conv
 322             This parameter is only used by wxFileConfig when compiled in
 323             Unicode mode. It specifies the encoding in which the configuration
 324             file is written.
 325
 326         @remarks By default, environment variable expansion is on and recording
 327                  defaults is off.
 328     */
 329     wxConfigBase(const wxString& appName = wxEmptyString,
 330                  const wxString& vendorName = wxEmptyString,
 331                  const wxString& localFilename = wxEmptyString,
 332                  const wxString& globalFilename = wxEmptyString,
 333                  long style = 0,
 334                  const wxMBConv& conv = wxConvAuto());
 335
 336     /**
 337         Empty but ensures that dtor of all derived classes is virtual.
 338     */
 339     virtual ~wxConfigBase();
 340
 341
 342     /**
 343         @name Path Management
 344
 345         See @ref configbase_paths
 346     */
 347     //@{
 348
 349     /**
 350         Retrieve the current path (always as absolute path).
 351     */
 352     virtual const wxString& GetPath() const = 0;
 353
 354     /**
 355         Set current path: if the first character is '/', it is the absolute
 356         path, otherwise it is a relative path. '..' is supported. If @a strPath
 357         doesn't exist, it is created.
 358
 359         @see wxConfigPathChanger
 360     */
 361     virtual void SetPath(const wxString& strPath) = 0;
 362
 363     //@}
 364
 365
 366     /**
 367         @name Enumeration
 368
 369         See @ref configbase_enumeration
 370     */
 371     //@{
 372
 373     /**
 374         Gets the first entry.
 375
 376         @beginWxPythonOnly
 377         The wxPython version of this method returns a 3-tuple consisting of the
 378         continue flag, the value string, and the index for the next call.
 379         @endWxPythonOnly
 380
 381         @beginWxPerlOnly
 382         In wxPerl this method takes no parameters and returns a 3-element
 383         list (continue_flag, string, index_for_getnextentry).
 384         @endWxPerlOnly
 385     */
 386     virtual bool GetFirstEntry(wxString& str, long& index) const = 0;
 387
 388     /**
 389         Gets the first group.
 390
 391         @beginWxPythonOnly
 392         The wxPython version of this method returns a 3-tuple consisting of the
 393         continue flag, the value string, and the index for the next call.
 394         @endWxPythonOnly
 395
 396         @beginWxPerlOnly
 397         In wxPerl this method takes no parameters and returns a 3-element
 398         list (continue_flag, string, index_for_getnextentry).
 399         @endWxPerlOnly
 400     */
 401     virtual bool GetFirstGroup(wxString& str, long& index) const = 0;
 402
 403     /**
 404         Gets the next entry.
 405
 406         @beginWxPythonOnly
 407         The wxPython version of this method returns a 3-tuple consisting of the
 408         continue flag, the value string, and the index for the next call.
 409         @endWxPythonOnly
 410
 411         @beginWxPerlOnly
 412         In wxPerl this method only takes the @a index parameter and
 413         returns a 3-element list (continue_flag, string,
 414         index_for_getnextentry).
 415         @endWxPerlOnly
 416     */
 417     virtual bool GetNextEntry(wxString& str, long& index) const = 0;
 418
 419     /**
 420         Gets the next group.
 421
 422         @beginWxPythonOnly
 423         The wxPython version of this method returns a 3-tuple consisting of the
 424         continue flag, the value string, and the index for the next call.
 425         @endWxPythonOnly
 426
 427         @beginWxPerlOnly
 428         In wxPerl this method only takes the @a index parameter and
 429         returns a 3-element list (continue_flag, string,
 430         index_for_getnextentry).
 431         @endWxPerlOnly
 432     */
 433     virtual bool GetNextGroup(wxString& str, long& index) const = 0;
 434
 435     /**
 436         Get number of entries in the current group.
 437     */
 438     virtual size_t GetNumberOfEntries(bool bRecursive = false) const = 0;
 439
 440     /**
 441         Get number of entries/subgroups in the current group, with or without
 442         its subgroups.
 443     */
 444     virtual size_t GetNumberOfGroups(bool bRecursive = false) const = 0;
 445
 446     //@}
 447
 448
 449     enum EntryType
 450     {
 451         Type_Unknown,
 452         Type_String,
 453         Type_Boolean,
 454         Type_Integer,
 455         Type_Float
 456     };
 457
 458     /**
 459         @name Tests of Existence
 460     */
 461     //@{
 462
 463     /**
 464         @return @true if either a group or an entry with a given name exists.
 465     */
 466     bool Exists(const wxString& strName) const;
 467
 468     /**
 469         Returns the type of the given entry or @e Unknown if the entry doesn't
 470         exist. This function should be used to decide which version of Read()
 471         should be used because some of wxConfig implementations will complain
 472         about type mismatch otherwise: e.g., an attempt to read a string value
 473         from an integer key with wxRegConfig will fail.
 474     */
 475     virtual wxConfigBase::EntryType GetEntryType(const wxString& name) const;
 476
 477     /**
 478         @return @true if the entry by this name exists.
 479     */
 480     virtual bool HasEntry(const wxString& strName) const = 0;
 481
 482     /**
 483         @return @true if the group by this name exists.
 484     */
 485     virtual bool HasGroup(const wxString& strName) const = 0;
 486
 487     //@}
 488
 489
 490     /**
 491         @name Miscellaneous Functions
 492     */
 493     //@{
 494
 495     /**
 496         Returns the application name.
 497     */
 498     wxString GetAppName() const;
 499
 500     /**
 501         Returns the vendor name.
 502     */
 503     wxString GetVendorName() const;
 504
 505     //@}
 506
 507
 508     /**
 509         @name Key Access
 510
 511         See @ref configbase_keyaccess
 512     */
 513     //@{
 514
 515     /**
 516         Permanently writes all changes (otherwise, they're only written from
 517         object's destructor).
 518     */
 519     virtual bool Flush(bool bCurrentOnly = false) = 0;
 520
 521     /**
 522         Read a string from the key, returning @true if the value was read. If
 523         the key was not found, @a str is not changed.
 524
 525         @beginWxPerlOnly
 526         Not supported by wxPerl.
 527         @endWxPerlOnly
 528     */
 529     bool Read(const wxString& key, wxString* str) const;
 530     /**
 531         Read a string from the key. The default value is returned if the key
 532         was not found.
 533
 534         @return @true if value was really read, @false if the default was used.
 535
 536         @beginWxPerlOnly
 537         Not supported by wxPerl.
 538         @endWxPerlOnly
 539     */
 540     bool Read(const wxString& key, wxString* str,
 541               const wxString& defaultVal) const;
 542     /**
 543         Another version of Read(), returning the string value directly.
 544
 545         @beginWxPerlOnly
 546         In wxPerl, this can be called as:
 547         - Read(key): returns the empty string if no key is found
 548         - Read(key, default): returns the default value if no key is found
 549         @endWxPerlOnly
 550     */
 551     const wxString Read(const wxString& key,
 552                         const wxString& defaultVal) const;
 553     /**
 554         Reads a long value, returning @true if the value was found. If the
 555         value was not found, @a l is not changed.
 556
 557         @beginWxPerlOnly
 558         Not supported by wxPerl.
 559         @endWxPerlOnly
 560     */
 561     bool Read(const wxString& key, long* l) const;
 562     /**
 563         Reads a long 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         - ReadInt(key): returns the 0 if no key is found
 569         - ReadInt(key, default): returns the default value if no key is found
 570         @endWxPerlOnly
 571     */
 572     bool Read(const wxString& key, long* l,
 573               long defaultVal) const;
 574     /**
 575         Reads a double value, returning @true if the value was found. If the
 576         value was not found, @a d is not changed.
 577
 578         @beginWxPerlOnly
 579         Not supported by wxPerl.
 580         @endWxPerlOnly
 581     */
 582     bool Read(const wxString& key, double* d) const;
 583     /**
 584         Reads a double value, returning @true if the value was found. If the
 585         value was not found, @a defaultVal is used instead.
 586
 587         @beginWxPerlOnly
 588         In wxPerl, this can be called as:
 589         - ReadFloat(key): returns the 0.0 if no key is found
 590         - ReadFloat(key, default): returns the default value if no key is found
 591         @endWxPerlOnly
 592     */
 593     bool Read(const wxString& key, double* d,
 594                      double defaultVal) const;
 595
 596     /**
 597         Reads a float value, returning @true if the value was found.
 598
 599         If the value was not found, @a f is not changed.
 600
 601         Notice that the value is read as a double but must be in a valid range
 602         for floats for the function to return @true.
 603
 604         @since 2.9.1
 605
 606         @beginWxPerlOnly
 607         Not supported by wxPerl.
 608         @endWxPerlOnly
 609     */
 610     bool Read(const wxString& key, float* f) const;
 611     /**
 612         Reads a float value, returning @true if the value was found.
 613
 614         If the value was not found, @a defaultVal is used instead.
 615
 616         Notice that the value is read as a double but must be in a valid range
 617         for floats for the function to return @true.
 618
 619         @since 2.9.1
 620
 621         @beginWxPerlOnly
 622         Not supported by wxPerl.
 623         @endWxPerlOnly
 624     */
 625     bool Read(const wxString& key, float* f, float defaultVal) const;
 626
 627     /**
 628         Reads a boolean value, returning @true if the value was found. If the
 629         value was not found, @a b is not changed.
 630
 631         @since 2.9.1
 632
 633         @beginWxPerlOnly
 634         Not supported by wxPerl.
 635         @endWxPerlOnly
 636     */
 637     bool Read(const wxString& key, bool* b) const;
 638     /**
 639         Reads a boolean value, returning @true if the value was found. If the
 640         value was not found, @a defaultVal is used instead.
 641
 642         @beginWxPerlOnly
 643         In wxPerl, this can be called as:
 644         - ReadBool(key): returns false if no key is found
 645         - ReadBool(key, default): returns the default value if no key is found
 646         @endWxPerlOnly
 647     */
 648     bool Read(const wxString& key, bool* d,
 649               bool defaultVal) const;
 650     /**
 651         Reads a binary block, returning @true if the value was found. If the
 652         value was not found, @a buf is not changed.
 653     */
 654     bool Read(const wxString& key, wxMemoryBuffer* buf) const;
 655     /**
 656         Reads a value of type T, for which function wxFromString() is defined,
 657         returning @true if the value was found. If the value was not found,
 658         @a value is not changed.
 659     */
 660     bool Read(const wxString& key, T* value) const;
 661     /**
 662         Reads a value of type T, for which function wxFromString() is defined,
 663         returning @true if the value was found. If the value was not found,
 664         @a defaultVal is used instead.
 665     */
 666     bool Read(const wxString& key, T* value,
 667               const T& defaultVal) const;
 668
 669     /**
 670         Reads a bool value from the key and returns it. @a defaultVal is
 671         returned if the key is not found.
 672     */
 673     bool ReadBool(const wxString& key, bool defaultVal) const;
 674
 675     /**
 676         Reads a double value from the key and returns it. @a defaultVal is
 677         returned if the key is not found.
 678     */
 679     double ReadDouble(const wxString& key, double defaultVal) const;
 680
 681     /**
 682         Reads a long value from the key and returns it. @a defaultVal is
 683         returned if the key is not found.
 684     */
 685     long ReadLong(const wxString& key, long defaultVal) const;
 686
 687     /**
 688         Reads a value of type T (for which the function wxFromString() must be
 689         defined) from the key and returns it. @a defaultVal is returned if the
 690         key is not found.
 691     */
 692     T ReadObject(const wxString& key, T const& defaultVal) const;
 693
 694     /**
 695         Writes the wxString value to the config file and returns @true on
 696         success.
 697     */
 698     bool Write(const wxString& key, const wxString& value);
 699     /**
 700         Writes the long value to the config file and returns @true on success.
 701     */
 702     bool Write(const wxString& key, long value);
 703     /**
 704         Writes the double value to the config file and returns @true on
 705         success.
 706
 707         Notice that if floating point numbers are saved as strings (as is the
 708         case with the configuration files used by wxFileConfig), this function
 709         uses the C locale for writing out the number, i.e. it will always use a
 710         period as the decimal separator, irrespectively of the current locale.
 711         This behaviour is new since wxWidgets 2.9.1 as the current locale was
 712         used before, but the change should be transparent because both C and
 713         current locales are tried when reading the numbers back.
 714     */
 715     bool Write(const wxString& key, double value);
 716     /**
 717         Writes the bool value to the config file and returns @true on success.
 718     */
 719     bool Write(const wxString& key, bool value);
 720     /**
 721         Writes the wxMemoryBuffer value to the config file and returns @true on
 722         success.
 723     */
 724     bool Write(const wxString& key, const wxMemoryBuffer& buf);
 725     /**
 726         Writes the specified value to the config file and returns @true on
 727         success. The function wxToString() must be defined for type @e T.
 728     */
 729     bool Write(const wxString& key, T const& buf);
 730
 731     //@}
 732
 733
 734     /**
 735         @name Rename Entries/Groups
 736
 737         These functions allow renaming entries or subgroups of the current
 738         group. They will return @false on error, typically because either the
 739         entry/group with the original name doesn't exist, because the
 740         entry/group with the new name already exists or because the function is
 741         not supported in this wxConfig implementation.
 742     */
 743     //@{
 744
 745     /**
 746         Renames an entry in the current group. The entries names (both the old
 747         and the new one) shouldn't contain backslashes, i.e. only simple names
 748         and not arbitrary paths are accepted by this function.
 749
 750         @return @false if @a oldName doesn't exist or if @a newName already
 751                 exists.
 752     */
 753     virtual bool RenameEntry(const wxString& oldName,
 754                              const wxString& newName) = 0;
 755
 756     /**
 757         Renames a subgroup of the current group. The subgroup names (both the
 758         old and the new one) shouldn't contain backslashes, i.e. only simple
 759         names and not arbitrary paths are accepted by this function.
 760
 761         @return @false if @a oldName doesn't exist or if @a newName already
 762                 exists.
 763     */
 764     virtual bool RenameGroup(const wxString& oldName,
 765                              const wxString& newName) = 0;
 766
 767     //@}
 768
 769
 770     /**
 771         @name Delete Entries/Groups
 772
 773         These functions delete entries and/or groups of entries from the config
 774         file. DeleteAll() is especially useful if you want to erase all traces
 775         of your program presence: for example, when you uninstall it.
 776     */
 777     //@{
 778
 779     /**
 780         Delete the whole underlying object (disk file, registry key, ...).
 781         Primarily for use by uninstallation routine.
 782     */
 783     virtual bool DeleteAll() = 0;
 784
 785     /**
 786         Deletes the specified entry and the group it belongs to if it was the
 787         last key in it and the second parameter is @true.
 788     */
 789     virtual bool DeleteEntry(const wxString& key,
 790                              bool bDeleteGroupIfEmpty = true) = 0;
 791
 792     /**
 793         Delete the group (with all subgroups). If the current path is under the
 794         group being deleted it is changed to its deepest still existing
 795         component. E.g. if the current path is @c "/A/B/C/D" and the group @c C
 796         is deleted, the path becomes @c "/A/B".
 797     */
 798     virtual bool DeleteGroup(const wxString& key) = 0;
 799
 800     //@}
 801
 802
 803     /**
 804         @name Options
 805
 806         Some aspects of wxConfigBase behaviour can be changed during run-time.
 807         The first of them is the expansion of environment variables in the
 808         string values read from the config file: for example, if you have the
 809         following in your config file:
 810
 811         @code
 812         # config file for my program
 813         UserData = $HOME/data
 814
 815         # the following syntax is valud only under Windows
 816         UserData = %windir%\\data.dat
 817         @endcode
 818
 819         The call to Read("UserData") will return something like
 820         @c "/home/zeitlin/data" on linux for example.
 821
 822         Although this feature is very useful, it may be annoying if you read a
 823         value which containts '$' or '%' symbols (% is used for environment
 824         variables expansion under Windows) which are not used for environment
 825         variable expansion. In this situation you may call
 826         SetExpandEnvVars(@false) just before reading this value and
 827         SetExpandEnvVars(@true) just after. Another solution would be to prefix
 828         the offending symbols with a backslash.
 829     */
 830     //@{
 831
 832     /**
 833         Returns @true if we are expanding environment variables in key values.
 834     */
 835     bool IsExpandingEnvVars() const;
 836
 837     /**
 838         Returns @true if we are writing defaults back to the config file.
 839     */
 840     bool IsRecordingDefaults() const;
 841
 842     /**
 843         Determine whether we wish to expand environment variables in key
 844         values.
 845     */
 846     void SetExpandEnvVars(bool bDoIt = true);
 847
 848     /**
 849         Sets whether defaults are recorded to the config file whenever an
 850         attempt to read the value which is not present in it is done.
 851
 852         If on (default is off) all default values for the settings used by the
 853         program are written back to the config file. This allows the user to
 854         see what config options may be changed and is probably useful only for
 855         wxFileConfig.
 856     */
 857     void SetRecordDefaults(bool bDoIt = true);
 858
 859     //@}
 860
 861
 862     /**
 863         Create a new config object and sets it as the current one.
 864
 865         This function will create the most appropriate implementation of
 866         wxConfig available for the current platform. By default this means that
 867         the system registry will be used for storing the configuration
 868         information under MSW and a file under the user home directory (see
 869         wxStandardPaths::GetUserConfigDir()) elsewhere.
 870
 871         If you prefer to use the configuration files everywhere, you can define
 872         @c wxUSE_CONFIG_NATIVE to 0 when compiling wxWidgets. Or you can simply
 873         always create wxFileConfig explicitly.
 874
 875         Finally, if you want to create a custom wxConfig subclass you may
 876         change this function behaviour by overriding wxAppTraits::CreateConfig()
 877         to create it. An example when this could be useful could be an
 878         application which could be installed either normally (in which case the
 879         default behaviour of using wxRegConfig is appropriate) or in a
 880         "portable" way in which case a wxFileConfig with a file in the program
 881         directory would be used and the choice would be done in CreateConfig()
 882         at run-time.
 883     */
 884     static wxConfigBase* Create();
 885
 886     /**
 887         Calling this function will prevent @e Get() from automatically creating
 888         a new config object if the current one is @NULL. It might be useful to
 889         call it near the program end to prevent "accidental" creation of a new
 890         config object.
 891     */
 892     static void DontCreateOnDemand();
 893
 894     /**
 895         Get the current config object. If there is no current object and
 896         @a CreateOnDemand is @true, this creates one (using Create()) unless
 897         DontCreateOnDemand() was called previously.
 898     */
 899     static wxConfigBase* Get(bool CreateOnDemand = true);
 900
 901     /**
 902         Sets the config object as the current one, returns the pointer to the
 903         previous current object (both the parameter and returned value may be
 904         @NULL).
 905     */
 906     static wxConfigBase* Set(wxConfigBase* pConfig);
 907 };
 908
 909
 910 /**
 911     @class wxConfigPathChanger
 912
 913     A handy little class which changes the current path in a wxConfig object and restores it in dtor.
 914     Declaring a local variable of this type, it's possible to work in a specific directory
 915     and ensure that the path is automatically restored when the function returns.
 916
 917     For example:
 918     @code
 919     // this function loads somes settings from the given wxConfig object;
 920     // the path selected inside it is left unchanged
 921     bool LoadMySettings(wxConfigBase* cfg)
 922     {
 923         wxConfigPathChanger changer(cfg, "/Foo/Data/SomeString");
 924         wxString str;
 925         if ( !config->Read("SomeString", &str) ) {
 926             wxLogError("Couldn't read SomeString!");
 927             return false;
 928                 // NOTE: without wxConfigPathChanger it would be easy to forget to
 929                 //       set the old path back into the wxConfig object before this return!
 930         }
 931
 932         // do something useful with SomeString...
 933
 934         return true;    // again: wxConfigPathChanger dtor will restore the original wxConfig path
 935     }
 936     @endcode
 937
 938     @library{wxbase}
 939     @category{cfg}
 940 */
 941 class WXDLLIMPEXP_BASE wxConfigPathChanger
 942 {
 943 public:
 944
 945     /**
 946         Changes the path of the given wxConfigBase object so that the key @a strEntry is accessible
 947         (for read or write).
 948
 949         In other words, the ctor uses wxConfigBase::SetPath() with everything which precedes the
 950         last slash of @a strEntry, so that:
 951         @code
 952         wxConfigPathChanger(wxConfigBase::Get(), "/MyProgram/SomeKeyName");
 953         @endcode
 954         has the same effect of:
 955         @code
 956         wxConfigPathChanger(wxConfigBase::Get(), "/MyProgram/");
 957         @endcode
 958     */
 959     wxConfigPathChanger(const wxConfigBase *pContainer, const wxString& strEntry);
 960
 961     /**
 962         Restores the path selected, inside the wxConfig object passed to the ctor, to the path which was
 963         selected when the wxConfigPathChanger ctor was called.
 964     */
 965     ~wxConfigPathChanger();
 966
 967     /**
 968         Returns the name of the key which was passed to the ctor.
 969         The "name" is just anything which follows the last slash of the string given to the ctor.
 970     */
 971     const wxString& Name() const { return m_strName; }
 972
 973     /**
 974         This method must be called if the original path inside the wxConfig object
 975         (i.e. the current path at the moment of creation of this wxConfigPathChanger object)
 976         could have been deleted, thus preventing wxConfigPathChanger from restoring the not
 977         existing (any more) path.
 978
 979         If the original path doesn't exist any more, the path will be restored to
 980         the deepest still existing component of the old path.
 981     */
 982     void UpdateIfDeleted();
 983 };
 984