What is exceptional control flow?
Exceptional control flow occurs at all levels of a computer system. For example, at the hardware level, events detected by the hardware trigger abrupt control transfers to exception handlers. At the operating systems level, the kernel transfers control from one user process to another via context switches.
What is called control flow in Python?
A program’s control flow is the order in which the program’s code executes. The control flow of a Python program is regulated by conditional statements, loops, and function calls. Raising and handling exceptions also affects control flow; exceptions are covered in Chapter 6.
Why is it called a trap instruction?
‘Trap’ because it intercepts an exception. When the CPU issues an “undefined operation” exception, it switches into supervisor mode and checks the low-order part of the instruction for an index into a jump table of routines which implement the desired behavior, for example, software floating point routines.
What is exceptional control?
When to use robust exception handling in Python?
Robust exception handling (in Python) – a “best practices for Python exceptions” blog post I wrote a while ago. You may find it useful. Exceptions exist for exceptional situations: events that are not a part of normal execution.
What’s the best way to catch exceptions in Python?
Use the most specific Exception constructor that semantically fits your issue. Be specific in your message, e.g.: ? raise ValueError (‘A very specific bad thing happened.’) Avoid raising a generic Exception. To catch it, you’ll have to catch all other more specific exceptions that subclass it.
Is it bad to end with sys.exit in Python?
Terminating with sys.exit might be considered bad form in python: exceptions are the proper way to generate/handle errors. To differentiate application-level exceptions from other python exceptions, we create a specialized class, which inherits from python’s Exception class.
How to avoid raising generic exceptions in Python?
Be specific in your message, e.g.: ? raise ValueError (‘A very specific bad thing happened.’) Avoid raising a generic Exception. To catch it, you’ll have to catch all other more specific exceptions that subclass it. ? raise Exception (‘I know Python!’) # Don’t! If you catch, likely to hide bugs. ?