On the application class there is a ‘format’ property that can be used to format values, but there is no corresponding methods to parse values back into PHP formats.
I suggest that the CFormatter class also include parsing functions, the same as the format ones, like parseDate, parseRaw, etc, so it could be used with a common API for both functions.
Also, the CLocale class contains all information that CFormatter could use to format the values, so to not break compatibility, I suggest the creation of a CLocaleFormatter class that formats/parses values using the locale.
Attached is a patch of a implementation I made of this, on Yii trunk.
Comments are welcome.