Error Handling

I sometimes say "the most important part of programming is error handling".

This is not true. Shown by how many programs, how many library routines, how much code, does not handle errors at all.  Successful programs, libraries, code.

How about "one of the hardest parts of programming is error handling"?  That error handling is hard is one of reasons it is so often neglected.

And "one of the biggest barriers to reuse is error handling".

In at least two senses:

(1) You pick up a tool or library, try to use it on what you believe to be correct input - and it craps out with something like a Python stack dump.  Rather than debug, you try something else. Whereas, if an error message had explained what the problem was - if the code had checked format, rather than assuming - then you might have fixed the input.

(2) In a much narrower sense, the error handling conventions a code assumes may get in the way.  E.g. I assume that you throw an exception, you assume that it returns 0. Or -1.  If throwing an exception, what type of exception object do I throw?  (I have given up, and just throw strings.)


Can you tell I am debugging Python today?  I'm not 100% sure, but the Python code I have encountered has made more such assumptions...