wxWidgets/interface/wx/config.h

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/////////////////////////////////////////////////////////////////////////////
// Name: config.h
// Purpose: interface of wxConfigBase
// Author: wxWidgets team
// RCS-ID: $Id$
// Licence: wxWindows license
/////////////////////////////////////////////////////////////////////////////
/**
@class wxConfigBase
wxConfigBase defines the basic interface of all config classes. It can not
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 Win32 or text-based config files under Unix (or
even Windows 3.1 .INI files if you're really unlucky). 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 Win32 and wxFileConfig otherwise.
See @ref overview_config 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:
@li @c <wx/config.h> - Let wxWidgets choose a wxConfig class for your
platform.
@li @c <wx/confbase.h> - Base config class.
@li @c <wx/fileconf.h> - wxFileConfig class.
@li @c <wx/msw/regconf.h> - wxRegConfig class, see also wxRegKey.
@section configbase_example Example
Here is how you would typically use this class:
@code
// using wxConfig instead of writing wxFileConfig or wxRegConfig enhances
// portability of the code
wxConfig *config = new wxConfig("MyAppName");
wxString str;
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;
@endcode
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.
@section configbase_static 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.
@section configbase_paths Path Management
As explained in the @ref overview_config "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!):
@code
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 );
@endcode
It is highly recommended that you restore the path to its old value on
function exit:
@code
void foo(wxConfigBase *config)
{
wxString strOldPath = config->GetPath();
config->SetPath("/Foo/Data");
// ...
config->SetPath(strOldPath);
}
@endcode
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 doesnt
save and restore the path):
@code
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 );
}
@endcode
Finally, the path separator in wxConfigBase and derived classes is always
"/", regardless of the platform (i.e. it is not "\\" under Windows).
@section configbase_enumeration 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:
@code
wxConfigBase *config = ...;
wxArrayString aNames;
// enumeration variables
wxString str;
long dummy;
// first enum all entries
bool bCont = config->GetFirstEntry(str, dummy);
while ( bCont ) {
aNames.Add(str);
bCont = GetConfig()->GetNextEntry(str, dummy);
}
// ... we have all entry names in aNames...
// now all groups...
bCont = GetConfig()->GetFirstGroup(str, dummy);
while ( bCont ) {
aNames.Add(str);
bCont = GetConfig()->GetNextGroup(str, dummy);
}
// ... we have all group (and entry) names in aNames...
@endcode
There are also functions to get the number of entries/subgroups without
actually enumerating them, but you will probably never need them.
@section configbase_keyaccess 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, @c long, @c double,
@c 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 @a szKey parameter for all these functions can
contain an arbitrary path (either relative or absolute), not just the
key name.
@beginWxPythonOnly
In place of a single overloaded method name, wxPython implements the
following methods:
- Read(key, default="") - Returns a string.
- ReadInt(key, default=0) - Returns an integer.
- ReadFloat(key, default=0.0) - Returns a floating point number.
- ReadBool(key, default=0) - Returns a boolean.
- Write(key, value) - Writes a string.
- WriteInt(key, value) - Writes an int.
- WriteFloat(key, value) - Writes a floating point number.
@endWxPythonOnly
@library{wxbase}
@category{cfg}
*/
class wxConfigBase : public wxObject
{
public:
/**
This is the default and only constructor of the wxConfigBase class, and
derived classes.
@param appName
The 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.
@param vendorName
The 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.
@param localFilename
Some config classes require a local filename. If this is not
present, but required, the application name will be used instead.
@param globalFilename
Some config classes require a global filename. If this is not
present, but required, the application name will be used instead.
@param style
Can 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, thie GLOBAL flag refers to HKLM key while LOCAL
one is for the usual HKCU one.
@n 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.
@n 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.
@n 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".
@n 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 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.
@param conv
This 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.
*/
wxConfigBase(const wxString& appName = wxEmptyString,
const wxString& vendorName = wxEmptyString,
const wxString& localFilename = wxEmptyString,
const wxString& globalFilename = wxEmptyString,
long style = 0,
const wxMBConv& conv = wxConvAuto());
/**
Empty but ensures that dtor of all derived classes is virtual.
*/
virtual ~wxConfigBase();
/**
@name Path Management
See @ref configbase_paths
*/
//@{
/**
Retrieve the current path (always as absolute path).
*/
virtual const wxString& GetPath() const = 0;
/**
Set current path: if the first character is '/', it is the absolute
path, otherwise it is a relative path. '..' is supported. If @a strPath
doesn't exist it is created.
*/
virtual void SetPath(const wxString& strPath) = 0;
//@}
/**
@name Enumeration
See @ref configbase_enumeration
*/
//@{
/**
Gets the first entry.
@beginWxPythonOnly
The wxPython version of this method returns a 3-tuple consisting of the
continue flag, the value string, and the index for the next call.
@endWxPythonOnly
*/
virtual bool GetFirstEntry(wxString& str, long& index) const = 0;
/**
Gets the first group.
@beginWxPythonOnly
The wxPython version of this method returns a 3-tuple consisting of the
continue flag, the value string, and the index for the next call.
@endWxPythonOnly
*/
virtual bool GetFirstGroup(wxString& str, long& index) const = 0;
/**
Gets the next entry.
@beginWxPythonOnly
The wxPython version of this method returns a 3-tuple consisting of the
continue flag, the value string, and the index for the next call.
@endWxPythonOnly
*/
virtual bool GetNextEntry(wxString& str, long& index) const = 0;
/**
Gets the next group.
@beginWxPythonOnly
The wxPython version of this method returns a 3-tuple consisting of the
continue flag, the value string, and the index for the next call.
@endWxPythonOnly
*/
virtual bool GetNextGroup(wxString& str, long& index) const = 0;
/**
Get number of entries in the current group.
*/
virtual size_t GetNumberOfEntries(bool bRecursive = false) const = 0;
/**
Get number of entries/subgroups in the current group, with or without
its subgroups.
*/
virtual size_t GetNumberOfGroups(bool bRecursive = false) const = 0;
//@}
enum EntryType
{
Type_Unknown,
Type_String,
Type_Boolean,
Type_Integer,
Type_Float
};
/**
@name Tests of Existence
*/
//@{
/**
@return @true if either a group or an entry with a given name exists.
*/
bool Exists(const wxString& strName) const;
/**
Returns the type of the given entry or @e 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 wxConfigBase::EntryType GetEntryType(const wxString& name) const;
/**
@return @true if the entry by this name exists.
*/
virtual bool HasEntry(const wxString& strName) const = 0;
/**
@return @true if the group by this name exists.
*/
virtual bool HasGroup(const wxString& strName) const = 0;
//@}
/**
@name Miscellaneous Functions
*/
//@{
/**
Returns the application name.
*/
wxString GetAppName() const;
/**
Returns the vendor name.
*/
wxString GetVendorName() const;
//@}
/**
@name Key Access
See @ref configbase_keyaccess
*/
//@{
/**
Permanently writes all changes (otherwise, they're only written from
object's destructor).
*/
virtual bool Flush(bool bCurrentOnly = false) = 0;
/**
Read a string from the key, returning @true if the value was read. If
the key was not found, @a str is not changed.
*/
bool Read(const wxString& key, wxString* str) const;
/**
Read a string from the key. The default value is returned if the key
was not found.
@return @true if value was really read, @false if the default was used.
*/
bool Read(const wxString& key, wxString* str,
const wxString& defaultVal) const;
/**
Another version of Read(), returning the string value directly.
*/
const wxString Read(const wxString& key,
const wxString& defaultVal) const;
/**
Reads a long value, returning @true if the value was found. If the
value was not found, @a l is not changed.
*/
bool Read(const wxString& key, long* l) const;
/**
Reads a long value, returning @true if the value was found. If the
value was not found, @a defaultVal is used instead.
*/
bool Read(const wxString& key, long* l,
long defaultVal) const;
/**
Reads a double value, returning @true if the value was found. If the
value was not found, @a d is not changed.
*/
bool Read(const wxString& key, double* d) const;
/**
Reads a double value, returning @true if the value was found. If the
value was not found, @a defaultVal is used instead.
*/
bool Read(const wxString& key, double* d,
double defaultVal) const;
/**
Reads a bool value, returning @true if the value was found. If the
value was not found, @a b is not changed.
*/
bool Read(const wxString& key, bool* b) const;
/**
Reads a bool value, returning @true if the value was found. If the
value was not found, @a defaultVal is used instead.
*/
bool Read(const wxString& key, bool* d,
bool defaultVal) const;
/**
Reads a binary block, returning @true if the value was found. If the
value was not found, @a buf is not changed.
*/
bool Read(const wxString& key, wxMemoryBuffer* buf) const;
/**
Reads a value of type T, for which function wxFromString() is defined,
returning @true if the value was found. If the value was not found,
@a value is not changed.
*/
bool Read(const wxString& key, T* value) const;
/**
Reads a value of type T, for which function wxFromString() is defined,
returning @true if the value was found. If the value was not found,
@a defaultVal is used instead.
*/
bool Read(const wxString& key, T* value,
const T& defaultVal) const;
/**
Reads a bool value from the key and returns it. @a defaultVal is
returned if the key is not found.
*/
bool ReadBool(const wxString& key, bool defaultVal) const;
/**
Reads a double value from the key and returns it. @a defaultVal is
returned if the key is not found.
*/
double ReadDouble(const wxString& key, double defaultVal) const;
/**
Reads a long value from the key and returns it. @a defaultVal is
returned if the key is not found.
*/
long ReadLong(const wxString& key, long defaultVal) const;
/**
Reads a value of type T (for which the function wxFromString() must be
defined) from the key and returns it. @a defaultVal is returned if the
key is not found.
*/
T ReadObject(const wxString& key, T const& defaultVal) const;
/**
Writes the wxString value to the config file and returns @true on
success.
*/
bool Write(const wxString& key, const wxString& value);
/**
Writes the long value to the config file and returns @true on success.
*/
bool Write(const wxString& key, long value);
/**
Writes the double value to the config file and returns @true on
success.
*/
bool Write(const wxString& key, double value);
/**
Writes the bool value to the config file and returns @true on success.
*/
bool Write(const wxString& key, bool value);
/**
Writes the wxMemoryBuffer value to the config file and returns @true on
success.
*/
bool Write(const wxString& key, const wxMemoryBuffer& buf);
/**
Writes the specified value to the config file and returns @true on
success. The function wxToString() must be defined for type @e T.
*/
bool Write(const wxString& key, T const& buf);
//@}
/**
@name Rename Entries/Groups
These functions allow renaming entries or subgroups of the current
group. They will return @false on error, typically because either the
entry/group with the original name doesn't exist, because the
entry/group with the new name already exists or because the function is
not supported in this wxConfig implementation.
*/
//@{
/**
Renames an entry in the current group. The entries names (both the old
and the new one) shouldn't contain backslashes, i.e. only simple names
and not arbitrary paths are accepted by this function.
@return @false if @a oldName doesn't exist or if @a newName already
exists.
*/
virtual bool RenameEntry(const wxString& oldName,
const wxString& newName) = 0;
/**
Renames a subgroup of the current group. The subgroup names (both the
old and the new one) shouldn't contain backslashes, i.e. only simple
names and not arbitrary paths are accepted by this function.
@return @false if @a oldName doesn't exist or if @a newName already
exists.
*/
virtual bool RenameGroup(const wxString& oldName,
const wxString& newName) = 0;
//@}
/**
@name Delete Entries/Groups
These functions delete entries and/or groups of entries from the config
file. DeleteAll() is especially useful if you want to erase all traces
of your program presence: for example, when you uninstall it.
*/
//@{
/**
Delete the whole underlying object (disk file, registry key, ...).
Primarly for use by uninstallation routine.
*/
virtual bool DeleteAll() = 0;
/**
Deletes the specified entry and the group it belongs to if it was the
last key in it and the second parameter is @true.
*/
virtual bool DeleteEntry(const wxString& key,
bool bDeleteGroupIfEmpty = true) = 0;
/**
Delete the group (with all subgroups). If the current path is under the
group being deleted it is changed to its deepest still existing
component. E.g. if the current path is @c "/A/B/C/D" and the group @c C
is deleted, the path becomes @c "/A/B".
*/
virtual bool DeleteGroup(const wxString& key) = 0;
//@}
/**
@name Options
Some aspects of wxConfigBase behaviour can be changed during run-time.
The first of them is the expansion of environment variables in the
string values read from the config file: for example, if you have the
following in your config file:
@code
# config file for my program
UserData = $HOME/data
# the following syntax is valud only under Windows
UserData = %windir%\\data.dat
@endcode
The call to Read("UserData") will return something like
@c "/home/zeitlin/data" on linux for example.
Although this feature is very useful, it may be annoying if you read a
value which containts '$' or '%' symbols (% is used for environment
variables expansion under Windows) which are not used for environment
variable expansion. In this situation you may call
SetExpandEnvVars(@false) just before reading this value and
SetExpandEnvVars(@true) just after. Another solution would be to prefix
the offending symbols with a backslash.
*/
//@{
/**
Returns @true if we are expanding environment variables in key values.
*/
bool IsExpandingEnvVars() const;
/**
Returns @true if we are writing defaults back to the config file.
*/
bool IsRecordingDefaults() const;
/**
Determine whether we wish to expand environment variables in key
values.
*/
void SetExpandEnvVars(bool bDoIt = true);
/**
Sets whether defaults are recorded to the config file whenever an
attempt to read the value which is not present in it is done.
If on (default is off) all default values for the settings used by the
program are written back to the config file. This allows the user to
see what config options may be changed and is probably useful only for
wxFileConfig.
*/
void SetRecordDefaults(bool bDoIt = true);
//@}
/**
Create a new config object: this function will create the "best"
implementation of wxConfig available for the current platform, see
comments near the definition of wxCONFIG_WIN32_NATIVE for details. It
returns the created object and also sets it as the current one.
*/
static wxConfigBase* Create();
/**
Calling this function will prevent @e Get() from automatically creating
a new config object if the current one is @NULL. It might be useful to
call it near the program end to prevent "accidental" creation of a new
config object.
*/
static void DontCreateOnDemand();
/**
Get the current config object. If there is no current object and
@a CreateOnDemand is @true, this creates one (using Create()) unless
DontCreateOnDemand() was called previously.
*/
static wxConfigBase* Get(bool CreateOnDemand = true);
/**
Sets the config object as the current one, returns the pointer to the
previous current object (both the parameter and returned value may be
@NULL).
*/
static wxConfigBase* Set(wxConfigBase* pConfig);
};