Version: 3.1.5
wxConfigBase Class Referenceabstract

#include <wx/config.h>

+ Inheritance diagram for wxConfigBase:

Detailed Description

wxConfigBase defines the basic interface of all config classes.

It cannot be used by itself (it is an abstract base class) and you will always use one of its derivations: wxFileConfig, wxRegConfig or any other.

However, usually you don't even need to know the precise nature of the class you're working with but you would just use the wxConfigBase methods. This allows you to write the same code regardless of whether you're working with the registry under Windows or text-based config files under Unix. To make writing the portable code even easier, wxWidgets provides a typedef wxConfig which is mapped onto the native wxConfigBase implementation on the given platform: i.e. wxRegConfig under Windows and wxFileConfig otherwise.

See wxConfig Overview for a description of all features of this class.

It is highly recommended to use static functions Get() and/or Set(), so please have a look at them.

Related Include Files:

Example

Here is how you would typically use this class:

// using wxConfig instead of writing wxFileConfig or wxRegConfig enhances
// portability of the code
wxConfig *config = new wxConfig("MyAppName");
if ( config->Read("LastPrompt", &str) ) {
// last prompt was found in the config file/registry and its value is
// now in str
// ...
}
else {
// no last prompt...
}
// another example: using default values and the full path instead of just
// key name: if the key is not found , the value 17 is returned
long value = config->ReadLong("/LastRun/CalculatedValues/MaxValue", 17);
// at the end of the program we would save everything back
config->Write("LastPrompt", str);
config->Write("/LastRun/CalculatedValues/MaxValue", value);
// the changes will be written back automatically
delete config;

This basic example, of course, doesn't show all wxConfig features, such as enumerating, testing for existence and deleting the entries and groups of entries in the config file, its abilities to automatically store the default values or expand the environment variables on the fly. However, the main idea is that using this class is easy and that it should normally do what you expect it to.

Note
In the documentation of this class, the words "config file" also mean "registry hive" for wxRegConfig and, generally speaking, might mean any physical storage where a wxConfigBase-derived class stores its data.

Static Functions

The static functions provided deal with the "default" config object. Although its usage is not at all mandatory it may be convenient to use a global config object instead of creating and deleting the local config objects each time you need one (especially because creating a wxFileConfig object might be a time consuming operation). In this case, you may create this global config object in the very start of the program and Set() it as the default. Then, from anywhere in your program, you may access it using the Get() function. This global wxConfig object will be deleted by wxWidgets automatically if it exists. Note that this implies that if you do delete this object yourself (usually in wxApp::OnExit()) you must use Set(NULL) to prevent wxWidgets from deleting it the second time.

As it happens, you may even further simplify the procedure described above: you may forget about calling Set(). When Get() is called and there is no current object, it will create one using Create() function. To disable this behaviour DontCreateOnDemand() is provided.

Note
You should use either Set() or Get() because wxWidgets library itself would take advantage of it and could save various information in it. For example wxFontMapper or Unix version of wxFileDialog have the ability to use wxConfig class.

Path Management

As explained in the config overview, the config classes support a file system-like hierarchy of keys (files) and groups (directories). As in the file system case, to specify a key in the config class you must use a path to it. Config classes also support the notion of the current group, which makes it possible to use the relative paths. To clarify all this, here is an example (it is only for the sake of demonstration, it doesn't do anything sensible!):

wxConfig *config = new wxConfig("FooBarApp");
// right now the current path is '/'
conf->Write("RootEntry", 1);
// go to some other place: if the group(s) don't exist, they will be created
conf->SetPath("/Group/Subgroup");
// create an entry in subgroup
conf->Write("SubgroupEntry", 3);
// '..' is understood
conf->Write("../GroupEntry", 2);
conf->SetPath("..");
wxASSERT( conf->ReadLong("Subgroup/SubgroupEntry", 0) == 3 );
// use absolute path: it is allowed, too
wxASSERT( conf->ReadLong("/RootEntry", 0) == 1 );

It is highly recommended that you restore the path to its old value on function exit:

void foo(wxConfigBase *config)
{
wxString strOldPath = config->GetPath();
config->SetPath("/Foo/Data");
// ...
config->SetPath(strOldPath);
}

Otherwise the assert in the following example will surely fail (we suppose here that the foo() function is the same as above except that it doesn’t save and restore the path):

void bar(wxConfigBase *config)
{
config->Write("Test", 17);
foo(config);
// we're reading "/Foo/Data/Test" here! -1 will probably be returned...
wxASSERT( config->ReadLong("Test", -1) == 17 );
}

Finally, the path separator in wxConfigBase and derived classes is always "/", regardless of the platform (i.e. it is not "\\" under Windows).

Enumeration

The enumeration functions allow you to enumerate all entries and groups in the config file. All functions here return false when there are no more items.

You must pass the same index to GetNext() and GetFirst() (don't modify it). Please note that it is not the index of the current item (you will have some great surprises with wxRegConfig if you assume this) and you shouldn't even look at it: it is just a "cookie" which stores the state of the enumeration. It can't be stored inside the class because it would prevent you from running several enumerations simultaneously, that's why you must pass it explicitly.

Having said all this, enumerating the config entries/groups is very simple:

wxConfigBase *config = ...;
// enumeration variables
long dummy;
// first enum all entries
bool bCont = config->GetFirstEntry(str, dummy);
while ( bCont ) {
aNames.Add(str);
bCont = config->GetNextEntry(str, dummy);
}
// ... we have all entry names in aNames...
// now all groups...
bCont = config->GetFirstGroup(str, dummy);
while ( bCont ) {
aNames.Add(str);
bCont = config->GetNextGroup(str, dummy);
}
// ... we have all group (and entry) names in aNames...

There are also functions to get the number of entries/subgroups without actually enumerating them, but you will probably never need them.

Key Access

The key access functions are the core of wxConfigBase class: they allow you to read and write config file data. All Read() functions take a default value which will be returned if the specified key is not found in the config file.

Currently, supported types of data are: wxString, long, double, bool, wxColour and any other types for which the functions wxToString() and wxFromString() are defined.

Try not to read long values into string variables and vice versa: although it just might work with wxFileConfig, you will get a system error with wxRegConfig because in the Windows registry the different types of entries are indeed used.

Final remark: the szKey parameter for all these functions can contain an arbitrary path (either relative or absolute), not just the key name.

Library:  wxBase
Category:  Application and System configuration
See also
wxConfigPathChanger

Public Types

enum  EntryType {
  Type_Unknown,
  Type_String,
  Type_Boolean,
  Type_Integer,
  Type_Float
}
 

Public Member Functions

 wxConfigBase (const wxString &appName=wxEmptyString, const wxString &vendorName=wxEmptyString, const wxString &localFilename=wxEmptyString, const wxString &globalFilename=wxEmptyString, long style=0, const wxMBConv &conv=wxConvAuto())
 This is the default and only constructor of the wxConfigBase class, and derived classes. More...
 
virtual ~wxConfigBase ()
 Empty but ensures that dtor of all derived classes is virtual. More...
 
Path Management
virtual const wxStringGetPath () const =0
 Retrieve the current path (always as absolute path). More...
 
virtual void SetPath (const wxString &strPath)=0
 Set current path: if the first character is '/', it is the absolute path, otherwise it is a relative path. More...
 
Enumeration
virtual bool GetFirstEntry (wxString &str, long &index) const =0
 Gets the first entry. More...
 
virtual bool GetFirstGroup (wxString &str, long &index) const =0
 Gets the first group. More...
 
virtual bool GetNextEntry (wxString &str, long &index) const =0
 Gets the next entry. More...
 
virtual bool GetNextGroup (wxString &str, long &index) const =0
 Gets the next group. More...
 
virtual size_t GetNumberOfEntries (bool bRecursive=false) const =0
 Get number of entries in the current group. More...
 
virtual size_t GetNumberOfGroups (bool bRecursive=false) const =0
 Get number of entries/subgroups in the current group, with or without its subgroups. More...
 
Tests of Existence
bool Exists (const wxString &strName) const
 
virtual wxConfigBase::EntryType GetEntryType (const wxString &name) const
 Returns the type of the given entry or Unknown if the entry doesn't exist. More...
 
virtual bool HasEntry (const wxString &strName) const =0
 
virtual bool HasGroup (const wxString &strName) const =0
 
Miscellaneous Functions
wxString GetAppName () const
 Returns the application name. More...
 
wxString GetVendorName () const
 Returns the vendor name. More...
 
Key Access
virtual bool Flush (bool bCurrentOnly=false)=0
 Permanently writes all changes (otherwise, they're only written from object's destructor). More...
 
bool Read (const wxString &key, wxString *str) const
 Read a string from the key, returning true if the value was read. More...
 
bool Read (const wxString &key, wxString *str, const wxString &defaultVal) const
 Read a string from the key. More...
 
const wxString Read (const wxString &key, const wxString &defaultVal) const
 Another version of Read(), returning the string value directly. More...
 
bool Read (const wxString &key, long *l) const
 Reads a long value, returning true if the value was found. More...
 
bool Read (const wxString &key, long *l, long defaultVal) const
 Reads a long value, returning true if the value was found. More...
 
bool Read (const wxString &key, wxLongLong_t *ll) const
 Reads a 64-bit long long value, returning true if the value was found. More...
 
- Public Member Functions inherited from wxObject
 wxObject ()
 Default ctor; initializes to NULL the internal reference data. More...
 
 wxObject (const wxObject &other)
 Copy ctor. More...
 
virtual ~wxObject ()
 Destructor. More...
 
virtual wxClassInfoGetClassInfo () const
 This virtual function is redefined for every class that requires run-time type information, when using the wxDECLARE_CLASS macro (or similar). More...
 
wxObjectRefDataGetRefData () const
 Returns the wxObject::m_refData pointer, i.e. the data referenced by this object. More...
 
bool IsKindOf (const wxClassInfo *info) const
 Determines whether this class is a subclass of (or the same class as) the given class. More...
 
bool IsSameAs (const wxObject &obj) const
 Returns true if this object has the same data pointer as obj. More...
 
void Ref (const wxObject &clone)
 Makes this object refer to the data in clone. More...
 
void SetRefData (wxObjectRefData *data)
 Sets the wxObject::m_refData pointer. More...
 
void UnRef ()
 Decrements the reference count in the associated data, and if it is zero, deletes the data. More...
 
void UnShare ()
 This is the same of AllocExclusive() but this method is public. More...
 
void operator delete (void *buf)
 The delete operator is defined for debugging versions of the library only, when the identifier WXDEBUG is defined. More...
 
void * operator new (size_t size, const wxString &filename=NULL, int lineNum=0)
 The new operator is defined for debugging versions of the library only, when the identifier WXDEBUG is defined. More...
 

Additional Inherited Members

- Protected Member Functions inherited from wxObject
void AllocExclusive ()
 Ensure that this object's data is not shared with any other object. More...
 
virtual wxObjectRefDataCreateRefData () const
 Creates a new instance of the wxObjectRefData-derived class specific to this object and returns it. More...
 
virtual wxObjectRefDataCloneRefData (const wxObjectRefData *data) const
 Creates a new instance of the wxObjectRefData-derived class specific to this object and initializes it copying data. More...
 
- Protected Attributes inherited from wxObject
wxObjectRefDatam_refData
 Pointer to an object which is the object's reference-counted data. More...
 

Member Enumeration Documentation

Enumerator
Type_Unknown 
Type_String 
Type_Boolean 
Type_Integer 
Type_Float 

Constructor & Destructor Documentation

wxConfigBase::wxConfigBase ( const wxString appName = wxEmptyString,
const wxString vendorName = wxEmptyString,
const wxString localFilename = wxEmptyString,
const wxString globalFilename = wxEmptyString,
long  style = 0,
const wxMBConv conv = wxConvAuto() 
)

This is the default and only constructor of the wxConfigBase class, and derived classes.

Parameters
appNameThe application name. If this is empty, the class will normally use wxApp::GetAppName() to set it. The application name is used in the registry key on Windows, and can be used to deduce the local filename parameter if that is missing.
vendorNameThe vendor name. If this is empty, it is assumed that no vendor name is wanted, if this is optional for the current config class. The vendor name is appended to the application name for wxRegConfig.
localFilenameSome config classes require a local filename. If this is not present, but required, the application name will be used instead.
globalFilenameSome config classes require a global filename. If this is not present, but required, the application name will be used instead.
styleCan be one of wxCONFIG_USE_LOCAL_FILE and wxCONFIG_USE_GLOBAL_FILE.
The style interpretation depends on the config class and is ignored by some implementations. For wxFileConfig, these styles determine whether a local or global config file is created or used: if wxCONFIG_USE_GLOBAL_FILE is used, then settings are read from the global config file and if wxCONFIG_USE_LOCAL_FILE is used, settings are read from and written to local config file (if they are both set, global file is read first, then local file, overwriting global settings). If the flag is present but the parameter is empty, the parameter will be set to a default. If the parameter is present but the style flag not, the relevant flag will be added to the style. For wxRegConfig, the GLOBAL flag refers to the HKLM key while LOCAL one is for the usual HKCU one.
For wxFileConfig you can also add wxCONFIG_USE_RELATIVE_PATH by logically or'ing it to either of the _FILE options to tell wxFileConfig to use relative instead of absolute paths.
On non-VMS Unix systems, the default local configuration file is "~/.appname". However, this path may be also used as user data directory (see wxStandardPaths::GetUserDataDir()) if the application has several data files. In this case wxCONFIG_USE_SUBDIR flag, which changes the default local configuration file to "~/.appname/appname" should be used. Notice that this flag is ignored if localFilename is provided. wxCONFIG_USE_SUBDIR is new since wxWidgets version 2.8.2.
For wxFileConfig, you can also add wxCONFIG_USE_NO_ESCAPE_CHARACTERS which will turn off character escaping for the values of entries stored in the config file: for example a foo key with some backslash characters will be stored as "foo=C:\mydir" instead of the usual storage of "foo=C:\\mydir".
The wxCONFIG_USE_NO_ESCAPE_CHARACTERS style can be helpful if your config file must be read or written to by a non-wxWidgets program (which might not understand the escape characters). Note, however, that if wxCONFIG_USE_NO_ESCAPE_CHARACTERS style is used, it is now your application's responsibility to ensure that there is no newline or other illegal characters in a value, before writing that value to the file.
convThis parameter is only used by wxFileConfig when compiled in Unicode mode. It specifies the encoding in which the configuration file is written.
Remarks
By default, environment variable expansion is on and recording defaults is off.
virtual wxConfigBase::~wxConfigBase ( )
virtual

Empty but ensures that dtor of all derived classes is virtual.

Member Function Documentation

bool wxConfigBase::Exists ( const wxString strName) const
Returns
true if either a group or an entry with a given name exists.
virtual bool wxConfigBase::Flush ( bool  bCurrentOnly = false)
pure virtual

Permanently writes all changes (otherwise, they're only written from object's destructor).

Implemented in wxFileConfig.

wxString wxConfigBase::GetAppName ( ) const

Returns the application name.

virtual wxConfigBase::EntryType wxConfigBase::GetEntryType ( const wxString name) const
virtual

Returns the type of the given entry or Unknown if the entry doesn't exist.

This function should be used to decide which version of Read() should be used because some of wxConfig implementations will complain about type mismatch otherwise: e.g., an attempt to read a string value from an integer key with wxRegConfig will fail.

virtual bool wxConfigBase::GetFirstEntry ( wxString str,
long &  index 
) const
pure virtual

Gets the first entry.

wxPerl Note: In wxPerl this method takes no parameters and returns a 3-element list (continue_flag, string, index_for_getnextentry).

Implemented in wxFileConfig.

virtual bool wxConfigBase::GetFirstGroup ( wxString str,
long &  index 
) const
pure virtual

Gets the first group.

wxPerl Note: In wxPerl this method takes no parameters and returns a 3-element list (continue_flag, string, index_for_getnextentry).

Implemented in wxFileConfig.

virtual bool wxConfigBase::GetNextEntry ( wxString str,
long &  index 
) const
pure virtual

Gets the next entry.

wxPerl Note: In wxPerl this method only takes the index parameter and returns a 3-element list (continue_flag, string, index_for_getnextentry).

Implemented in wxFileConfig.

virtual bool wxConfigBase::GetNextGroup ( wxString str,
long &  index 
) const
pure virtual

Gets the next group.

wxPerl Note: In wxPerl this method only takes the index parameter and returns a 3-element list (continue_flag, string, index_for_getnextentry).

Implemented in wxFileConfig.

virtual size_t wxConfigBase::GetNumberOfEntries ( bool  bRecursive = false) const
pure virtual

Get number of entries in the current group.

Implemented in wxFileConfig.

virtual size_t wxConfigBase::GetNumberOfGroups ( bool  bRecursive = false) const
pure virtual

Get number of entries/subgroups in the current group, with or without its subgroups.

Implemented in wxFileConfig.

virtual const wxString& wxConfigBase::GetPath ( ) const
pure virtual

Retrieve the current path (always as absolute path).

Implemented in wxFileConfig.

wxString wxConfigBase::GetVendorName ( ) const

Returns the vendor name.

virtual bool wxConfigBase::HasEntry ( const wxString strName) const
pure virtual
Returns
true if the entry by this name exists.

Implemented in wxFileConfig.

virtual bool wxConfigBase::HasGroup ( const wxString strName) const
pure virtual
Returns
true if the group by this name exists.

Implemented in wxFileConfig.

bool wxConfigBase::Read ( const wxString key,
wxString str 
) const

Read a string from the key, returning true if the value was read.

If the key was not found, str is not changed.

wxPerl Note: Not supported by wxPerl.

bool wxConfigBase::Read ( const wxString key,
wxString str,
const wxString defaultVal 
) const

Read a string from the key.

The default value is returned if the key was not found.

Returns
true if value was really read, false if the default was used.

wxPerl Note: Not supported by wxPerl.

const wxString wxConfigBase::Read ( const wxString key,
const wxString defaultVal 
) const

Another version of Read(), returning the string value directly.

wxPerl Note: In wxPerl, this can be called as:

  • Read(key): returns the empty string if no key is found
  • Read(key, default): returns the default value if no key is found
bool wxConfigBase::Read ( const wxString key,
long *  l 
) const

Reads a long value, returning true if the value was found.

If the value was not found, l is not changed.

wxPerl Note: Not supported by wxPerl.

bool wxConfigBase::Read ( const wxString key,
long *  l,
long  defaultVal 
) const

Reads a long value, returning true if the value was found.

If the value was not found, defaultVal is used instead.

wxPerl Note: In wxPerl, this can be called as:

  • ReadInt(key): returns the 0 if no key is found
  • ReadInt(key, default): returns the default value if no key is found
bool wxConfigBase::Read ( const wxString key,
wxLongLong_t *  ll 
) const

Reads a 64-bit long long value, returning true if the value was found.

If the value was not found, ll is not changed.

Since
3.1.5

wxPerl Note: Not supported by wxPerl.

virtual void wxConfigBase::SetPath ( const wxString strPath)
pure virtual

Set current path: if the first character is '/', it is the absolute path, otherwise it is a relative path.

'..' is supported. If strPath doesn't exist, it is created.

See also
wxConfigPathChanger

Implemented in wxFileConfig.