Python Runtime Services

The modules described in this chapter provide a wide range of services related to the Python interpreter and its interaction with its environment. Here’s an overview:

• sys — System-specific parameters and functions
• sys.monitoring — Execution event monitoring
  • Tool identifiers
    • Registering and using tools
  • Events
    • Local events
    • Deprecated event
    • Ancillary events
    • Other events
    • The STOP_ITERATION event
  • Turning events on and off
    • Setting events globally
    • Per code object events
    • Disabling events
  • Registering callback functions
    • Callback function arguments
• sysconfig — Provide access to Python’s configuration information
  • Configuration variables
  • Installation paths
  • User scheme
    • posix_user
    • nt_user
    • osx_framework_user
  • Home scheme
    • posix_home
  • Prefix scheme
    • posix_prefix
    • nt
  • Installation path functions
  • Other functions
  • Command-line usage
• builtins — Built-in objects
• __main__ — Top-level code environment
  • __name__ == '__main__'
    • What is the “top-level code environment”?
    • Idiomatic Usage
    • Packaging Considerations
  • __main__.py in Python Packages
    • Idiomatic Usage
  • import __main__
• warnings — Warning control
  • Warning Categories
  • The Warnings Filter
    • Repeated Warning Suppression Criteria
    • Describing Warning Filters
    • Default Warning Filter
    • Overriding the default filter
  • Temporarily Suppressing Warnings
  • Testing Warnings
  • Updating Code For New Versions of Dependencies
  • Available Functions
  • Available Context Managers
  • Concurrent safety of Context Managers
• dataclasses — Data Classes
  • Module contents
  • Post-init processing
  • Class variables
  • Init-only variables
  • Frozen instances
  • Inheritance
  • Re-ordering of keyword-only parameters in __init__()
  • Default factory functions
  • Mutable default values
  • Descriptor-typed fields
• contextlib — Utilities for with-statement contexts
  • Utilities
  • Examples and Recipes
    • Supporting a variable number of context managers
    • Catching exceptions from __enter__ methods
    • Cleaning up in an __enter__ implementation
    • Replacing any use of try-finally and flag variables
    • Using a context manager as a function decorator
  • Single use, reusable and reentrant context managers
    • Reentrant context managers
    • Reusable context managers
• abc — Abstract Base Classes
• atexit — Exit handlers
  • atexit Example
• traceback — Print or retrieve a stack traceback
  • Module-Level Functions
  • TracebackException Objects
  • StackSummary Objects
  • FrameSummary Objects
  • Examples of Using the Module-Level Functions
  • Examples of Using TracebackException
• __future__ — Future statement definitions
  • Module Contents
• gc — Garbage Collector interface
• inspect — Inspect live objects
  • Types and members
  • Retrieving source code
  • Introspecting callables with the Signature object
  • Classes and functions
  • The interpreter stack
  • Fetching attributes statically
  • Current State of Generators, Coroutines, and Asynchronous Generators
  • Code Objects Bit Flags
  • Buffer flags
  • Command-line interface
• annotationlib — Functionality for introspecting annotations
  • Annotation semantics
  • Classes
  • Functions
  • Recipes
    • Using annotations in a metaclass
    • Creating a custom callable annotate function
  • Limitations of the STRING format
  • Limitations of the FORWARDREF format
  • Security implications of introspecting annotations
• site — Site-specific configuration hook
  • sitecustomize
  • usercustomize
  • Readline configuration
  • Module contents
  • Command-line interface