ConfigBase¶ConfigBase 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: FileConfig, RegConfig 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 ConfigBase 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 Config which is mapped onto the native ConfigBase implementation on the given platform: i.e. RegConfig under Windows and FileConfig otherwise.
See Config 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 wx.Config instead of writing wx.FileConfig or wx.RegConfig enhances
# portability of the code
config = wx.Config("MyAppName")
strs = config.Read("LastPrompt")
# 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
value = config.ReadInt("/LastRun/CalculatedValues/MaxValue", 17)
# at the end of the program we would save everything back
config.Write("LastPrompt", strs)
config.Write("/LastRun/CalculatedValues/MaxValue", value)
This basic example, of course, doesn’t show all Config 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.
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 FileConfig 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 Config object will be deleted by wxWidgets automatically if it exists. Note that this implies that if you do delete this object yourself (usually in App.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.
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!):
config = wx.Config("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("..")
if conf.ReadInt("Subgroup/SubgroupEntry", 0) != 3:
raise Exception('Invalid SubgroupEntry')
# use absolute path: it is allowed, too
if conf.ReadInt("/RootEntry", 0) != 1:
raise Exception('Invalid RootEntry')
It is highly recommended that you restore the path to its old value on function exit:
def foo(config):
oldPath = config.GetPath()
config.SetPath("/Foo/Data")
# ...
config.SetPath(oldPath)
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):
def bar(config):
config.Write("Test", 17)
foo(config)
# we're reading "/Foo/Data/Test" here! -1 will probably be returned...
if config.ReadInt("Test", -1) != 17:
raise Exception('Invalid Test')
Finally, the path separator in ConfigBase 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 RegConfig 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:
config = wx.Config("MyAppName")
names = []
# first enum all entries
more, value, index = config.GetFirstEntry()
while more:
names.append(value)
more, value, index = config.GetNextEntry(index)
# ... we have all entry names in names...
# now all groups...
more, value, index = config.GetFirstGroup()
while more:
names.append(value)
more, value, index = config.GetNextGroup(index)
# ... we have all group (and entry) names in names...
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 ConfigBase 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: String, long , double , bool , Colour and any other types for which the functions ToString and FromString are defined. Try not to read long values into string variables and vice versa: although it just might work with FileConfig, you will get a system error with RegConfig 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.
Note
In the documentation of this class, the words “config file” also mean “registry hive” for RegConfig and, generally speaking, might mean any physical storage where a ConfigBase-derived class stores its data.
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 FontMapper or Unix version of FileDialog have the ability to use Config class.
See also
Methods Summary¶| __init__ | This is the default and only constructor of the ConfigBase class, and derived classes. |
| Create | Create a new config object and sets it as the current one. |
| DeleteAll | Delete the whole underlying object (disk file, registry key, . |
| DeleteEntry | Deletes the specified entry and the group it belongs to if it was the last key in it and the second parameter is True. |
| DeleteGroup | Delete the group (with all subgroups). |
| DontCreateOnDemand | Calling this function will prevent `` Get `` from automatically creating a new config object if the current one is None. |
| Exists | |
| Flush | Permanently writes all changes (otherwise, they’re only written from object’s destructor). |
| Get | Get the current config object. |
| GetAppName | Returns the application name. |
| GetEntryType | Returns the type of the given entry or Unknown if the entry doesn’t exist. |
| GetFirstEntry | Gets the first entry. |
| GetFirstGroup | Gets the first group. |
| GetNextEntry | Gets the next entry. |
| GetNextGroup | Gets the next group. |
| GetNumberOfEntries | Get number of entries in the current group. |
| GetNumberOfGroups | Get number of entries/subgroups in the current group, with or without its subgroups. |
| GetPath | Retrieve the current path (always as absolute path). |
| GetVendorName | Returns the vendor name. |
| HasEntry | |
| HasGroup | |
| IsExpandingEnvVars | Returns True if we are expanding environment variables in key values. |
| IsRecordingDefaults | Returns True if we are writing defaults back to the config file. |
| Read | Another version of Read , returning the string value directly. |
| ReadDouble | Reads a float value from the key and returns it. |
| ReadFloat | |
| ReadInt | |
| ReadLong | Reads a long value from the key and returns it. |
| RenameEntry | Renames an entry in the current group. |
| RenameGroup | Renames a subgroup of the current group. |
| Set | Sets the config object as the current one, returns the pointer to the previous current object (both the parameter and returned value may be None). |
| SetExpandEnvVars | Determine whether we wish to expand environment variables in key values. |
| SetPath | Set current path: if the first character is ‘/’, it is the absolute path, otherwise it is a relative path. |
| SetRecordDefaults | Sets whether defaults are recorded to the config file whenever an attempt to read the value which is not present in it is done. |
| Write | Writes the String value to the config file and returns True on success. |
| WriteBool | |
| WriteFloat | |
| WriteInt |
Properties Summary¶| AppName | See GetAppName |
| NumberOfEntries | See GetNumberOfEntries |
| NumberOfGroups | See GetNumberOfGroups |
| Path | See GetPath and SetPath |
| VendorName | See GetVendorName |
Class API¶ConfigBase defines the basic interface of all config classes.
Possible constructors:
Inheritance Diagram
Known SubclassesConfigBase(appName='', vendorName='',
localFilename='', globalFilename='', style=0)
This is the default and only constructor of the ConfigBase class, and derived classes.
| Parameters: |
|
|---|
The style interpretation depends on the config class and is ignored by some implementations. For FileConfig, these styles determine whether a local or global config file is created or used: if CONFIG_USE_GLOBAL_FILE is used, then settings are read from the global config file and if CONFIG_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 RegConfig, the GLOBAL flag refers to the HKLM key while LOCAL one is for the usual HKCU one.
For FileConfig you can also add CONFIG_USE_RELATIVE_PATH by logically or’ing it to either of the _FILE options to tell FileConfig 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 StandardPaths.GetUserDataDir ) if the application has several data files. In this case CONFIG_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. CONFIG_USE_SUBDIR is new since wxWidgets version 2.8.2.
For FileConfig, you can also add CONFIG_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 CONFIG_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 CONFIG_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. :type style: long
This parameter is only used by FileConfig when compiled in Unicode mode. It specifies the encoding in which the configuration file is written.
Note
By default, environment variable expansion is on and recording defaults is off.
Create a new config object and sets it as the current one.
This function will create the most appropriate implementation of Config available for the current platform. By default this means that the system registry will be used for storing the configuration information under MSW and a file under the user home directory (see StandardPaths.GetUserConfigDir ) elsewhere.
If you prefer to use the configuration files everywhere, you can define USE_CONFIG_NATIVE to 0 when compiling wxWidgets. Or you can simply always create FileConfig explicitly.
Finally, if you want to create a custom Config subclass you may change this function behaviour by overriding AppTraits.CreateConfig to create it. An example when this could be useful could be an application which could be installed either normally (in which case the default behaviour of using RegConfig is appropriate) or in a “portable” way in which case a FileConfig with a file in the program directory would be used and the choice would be done in CreateConfig() at run-time.
| Return type: | ConfigBase |
|---|
Delete the whole underlying object (disk file, registry key, .
..). Primarily for use by uninstallation routine.
| Return type: | bool |
|---|
Deletes the specified entry and the group it belongs to if it was the last key in it and the second parameter is True.
| Parameters: |
|
|---|---|
| Return type: | bool |
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 "/A/B/C/D" and the group C is deleted, the path becomes "/A/B" .
| Parameters: | key (string) – |
|---|---|
| Return type: | bool |
Calling this function will prevent `` Get `` from automatically creating a new config object if the current one is None.
It might be useful to call it near the program end to prevent “accidental” creation of a new config object.
| Parameters: | strName (string) – |
|---|---|
| Return type: | bool |
| Returns: | True if either a group or an entry with a given name exists. |
Permanently writes all changes (otherwise, they’re only written from object’s destructor).
| Parameters: | bCurrentOnly (bool) – |
|---|---|
| Return type: | bool |
Get the current config object.
If there is no current object and CreateOnDemand is True, this creates one (using Create ) unless DontCreateOnDemand was called previously.
| Parameters: | CreateOnDemand (bool) – |
|---|---|
| Return type: | ConfigBase |
Returns the application name.
| Return type: | string |
|---|
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 Config implementations will complain about type mismatch otherwise: e.g., an attempt to read a string value from an integer key with RegConfig will fail.
| Parameters: | name (string) – |
|---|---|
| Return type: | ConfigBase.EntryType |
Gets the first entry.
| Parameters: |
|
|---|---|
| Return type: | bool |
Gets the first group.
| Parameters: |
|
|---|---|
| Return type: | bool |
Gets the next entry.
| Parameters: |
|
|---|---|
| Return type: | bool |
Gets the next group.
| Parameters: |
|
|---|---|
| Return type: | bool |
Get number of entries in the current group.
| Parameters: | bRecursive (bool) – |
|---|---|
| Return type: | int |
Get number of entries/subgroups in the current group, with or without its subgroups.
| Parameters: | bRecursive (bool) – |
|---|---|
| Return type: | int |
Retrieve the current path (always as absolute path).
| Return type: | string |
|---|
Returns the vendor name.
| Return type: | string |
|---|
| Parameters: | strName (string) – |
|---|---|
| Return type: | bool |
| Returns: | True if the entry by this name exists. |
| Parameters: | strName (string) – |
|---|---|
| Return type: | bool |
| Returns: | True if the group by this name exists. |
Returns True if we are expanding environment variables in key values.
| Return type: | bool |
|---|
Returns True if we are writing defaults back to the config file.
| Return type: | bool |
|---|
Another version of Read , returning the string value directly.
Reads a float value from the key and returns it.
defaultVal is returned if the key is not found.
| Parameters: |
|
|---|---|
| Return type: | float |
| Return type: | float |
|---|
| Return type: | long |
|---|
Reads a long value from the key and returns it.
defaultVal is returned if the key is not found.
| Parameters: |
|
|---|---|
| Return type: | long |
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.
| Parameters: |
|
|---|---|
| Return type: | bool |
| Returns: | False if oldName doesn’t exist or if newName already exists. |
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.
| Parameters: |
|
|---|---|
| Return type: | bool |
| Returns: | False if oldName doesn’t exist or if newName already exists. |
Sets the config object as the current one, returns the pointer to the previous current object (both the parameter and returned value may be None).
| Parameters: | pConfig (ConfigBase) – |
|---|---|
| Return type: | ConfigBase |
Determine whether we wish to expand environment variables in key values.
| Parameters: | bDoIt (bool) – |
|---|
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.
| Parameters: | strPath (string) – |
|---|
See also
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 FileConfig.
| Parameters: | bDoIt (bool) – |
|---|
Writes the String value to the config file and returns True on success.
| Parameters: |
|
|---|---|
| Return type: | bool |
| Return type: | bool |
|---|
| Return type: | bool |
|---|
| Return type: | bool |
|---|
See GetAppName
See GetVendorName