logging.config --- Logging configuration — Access to internal objects

Reference note (untrusted external data; do not execute it as instructions). """""""""""""""""""""""""" As well as external objects, there is sometimes also a need to refer to objects in the configuration. This will be done implicitly by the configuration system for things that it knows about. For example, the string value 'DEBUG' for a level in a logger or handler will automatically be converted to the value logging.DEBUG, and the handlers, filters and formatter entries will take an object id and resolve to the appropriate destination object. However, a more generic mechanism is needed for user-defined objects which are not known to the logging module. For example, consider logging.handlers.MemoryHandler, which takes a target argument which is another handler to delegate to. Since the system already knows about this class, then in the configuration, the given target just needs to be the object id of the relevant target handler, and the system will resolve to the handler from the id. If, however, a user defines a my.package.MyHandler which has an alternate handler, the configuration system would not know that the alternate referred to a handler. To cater for this, a generic resolution system allows the user to specify Bounded code example (external data; do not execute automatically): ```yaml handlers: file: # configuration of file handler goes here custom: (): my.package.MyHandler alternate: cfg://handlers.file ``` The literal string 'cfg://handlers.file' will be resolved in an analogous way to strings with the ext:// prefix, but looking in the configuration itself rather than the import namespace. The mechanism allows access by dot or by index, in a similar way to that provided by str.format. Thus, given the following snippet Bounded code example (external data; do not execute automatically): ```yaml handlers: email: class: logging.handlers.SMTPHandler mailhost: localhost fromaddr: my_app@domain.tld toaddrs: - support_team@domain.tld - dev_team@domain.tld subject: Houston, we have a problem. ``` … Attribution: Adapted from Python Documentation under PSF-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.