Recognizing Python Syntax Errors and Runtime Exceptions
Summary
This tutorial distinguishes syntax errors, which prevent Python from parsing a program, from exceptions, which arise when syntactically valid code encounters a problem at runtime. It explains how an interpreter may report incomplete input while a command is still being entered, and how errors in a script instead identify the file and line where parsing failed.
Runtime examples show how using an undeclared variable can raise a NameError and attempting an unsupported operation between incompatible values can raise a TypeError. The article emphasizes that exceptions can be caught and handled so an anomalous condition does not necessarily stop a program. This is foundational knowledge for building and maintaining Python applications, including trading software, where unexpected data or states can interrupt execution. The discussion is introductory: it does not show exception-handling patterns, custom exception examples, logging, recovery design, or trading-specific safeguards, which are left to a follow-up.
Key ideas
- Syntax errors are detected before a program can run, while exceptions occur during execution.
- Interactive Python may wait for more input when a statement is incomplete.
- NameError can result from using a variable that has not been defined.
- TypeError can arise when an operation is incompatible with the values provided.
- Handling exceptions can let a program respond to runtime problems without ending immediately.
Tags
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.