Improve XML Dependency Handling and Documentation in subyt Submodule

[cedricdcc]

There are several improvements needed regarding the handling of xmlasdict dependency and XML processing within the subyt submodule. These improvements include documentation updates, warning messages, and potentially registering a fake source class. Below are the specific tasks and suggestions:

1. Update Documentation:

   • Clarify that xmlasdict is not a required dependency for the general use of subyt. It is only needed for XML inputs, primarily used inside tests.
   • Make it explicit in the documentation that any usage of XML inputs declares its own dependency on xmlasdict.

2. Improve Warning Messages:

   • Currently, there is a log.warn message indicating that XML support is not available if the xmlasdict dependency is not met.
   • Extend this policy to provide a more upfront message or failure when XML processing is actually attempted without the xmlasdict dependency. --> this will most likely require the next suggestion!

3. Register a Fake Source Class (New Feature):

   • Consider registering a fake source class that explicitly informs users when they try to input files requiring XMLSource.
   • This fake source class should make it clear that XML processing requires the xmlasdict dependency and guide users accordingly.

Tasks

1. Documentation Update:

   • Add a section in the documentation explaining the optional nature of xmlasdict.
   • Explicitly state that handling XML inputs requires the xmlasdict dependency.

2. Warning Message Enhancement:

   • Enhance the existing log.warn to provide a more detailed and upfront message when XML processing is attempted without the xmlasdict dependency.
   • Ensure that the system fails gracefully and informatively when XML processing is attempted without the necessary dependency.

3. Register Fake Source Class:

   • Design and implement a fake source class to handle cases where XML inputs are provided without xmlasdict.
   • Ensure that this class provides clear guidance and error messages to users.

Additional Notes

• The current log.warn implementation already provides a warning about XML support being unavailable when the xmlasdict dependency is missing. The proposed enhancements aim to make this more user-friendly and informative.
• These changes should improve user experience by providing clearer instructions and preventing confusion related to XML processing dependencies.