Coding the markets

Debugging Twisted code is an exercise in lateral thinking. The error messages and exceptions can be opaque, especially when code wrapped inside a Deferred fails. When you get an unhandled error inside a Deferred, check your code for basic errors: parameter mismatches, references to undefined variables, or unimported types or modules etc. And where you’re deriving from a Twisted base class, check that you’re not accidently overriding a member variable. For instance, don’t have a member variable called ‘clients’ !