Readonly dirtyThe preference service is 'dirty' if there are changes to user preferences that have not been written to disk
Optional aInstancePtr: objectA run time mechanism for interface discovery.
NS_OK if the interface is supported by the associated instance, NS_NOINTERFACE if it is not.
aInstancePtr must not be null.
[in] A requested interface IID
[out] A pointer to an interface pointer to receive the result.
Call to get a Preferences "Branch" which accesses user preference data. Using a Set method on this object will always create or set a user preference value. When using a Get method a user set value will be returned if one exists, otherwise a default value will be returned.
nsIPrefBranch The object representing the requested branch.
getDefaultBranch
The preference "root" on which to base this "branch". For example, if the root "browser.startup." is used, the branch will be able to easily access the preferences "browser.startup.page", "browser.startup.homepage", or "browser.startup.homepage_override" by simply requesting "page", "homepage", or "homepage_override". nullptr or "" may be used to access to the entire preference "tree".
Call to get a Preferences "Branch" which accesses only the default preference data. Using a Set method on this object will always create or set a default preference value. When using a Get method a default value will always be returned.
Few consumers will want to create default branch objects. Many of the branch methods do nothing on a default branch because the operations only make sense when applied to user set preferences.
nsIPrefBranch The object representing the requested default branch.
getBranch
The preference "root" on which to base this "branch". For example, if the root "browser.startup." is used, the branch will be able to easily access the preferences "browser.startup.page", "browser.startup.homepage", or "browser.startup.homepage_override" by simply requesting "page", "homepage", or "homepage_override". nullptr or "" may be used to access to the entire preference "tree".
Parse the given bytes, invoking callbacks on the given observer.
This method does not modify any preferences.
The data to parse. This data may be UTF-8 encoded, but is not required to be so: the prefs parser will determine the encoding automatically.
The observer to invoke callbacks on. Parsing errors will be reported via the onError callback.
An optional string with which to label errors.
Read in the preferences specified in a default preference file. This method does not clear preferences that were already set, but it may overwrite existing preferences.
Error File failed to read or contained invalid data.
This method is intended for internal unit testing only!
The file to be read.
Usage statistics for performance tests. This function takes a function that is passed (preferenceName, accessCount) as arguments for every recorded preference. You can use this function to build e.g. a JS object holding that data.
This is not implemented in non-debug builds and will throw an error.
Called to write current preferences state to a file.
If nullptr is passed in for the aFile parameter the preference data is written out to the current preferences file (usually prefs.js.)
Error File failed to write.
The file to be written.
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The nsIPrefService interface is the main entry point into the back end preferences management library. The preference service is directly responsible for the management of the preferences files and also facilitates access to the preference branch object which allows the direct manipulation of the preferences themselves.
See
nsIPrefBranch