29. 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:

• 29.1. sys — System-specific parameters and functions
  • abiflags
  • argv
  • base_exec_prefix
  • base_prefix
  • byteorder
  • builtin_module_names
  • call_tracing()
  • copyright
  • _clear_type_cache()
  • _current_frames()
  • _debugmallocstats()
  • dllhandle
  • displayhook()
  • dont_write_bytecode
  • excepthook()
  • __displayhook__
  • __excepthook__
  • exc_info()
  • exec_prefix
  • executable
  • exit()
  • flags
  • float_info
  • float_repr_style
  • getallocatedblocks()
  • getcheckinterval()
  • getdefaultencoding()
  • getdlopenflags()
  • getfilesystemencoding()
  • getfilesystemencodeerrors()
  • get_int_max_str_digits()
  • getrefcount()
  • getrecursionlimit()
  • getsizeof()
  • getswitchinterval()
  • _getframe()
  • getprofile()
  • gettrace()
  • getwindowsversion()
  • get_asyncgen_hooks()
  • get_coroutine_wrapper()
  • hash_info
  • hexversion
  • implementation
  • int_info
  • __interactivehook__
  • intern()
  • is_finalizing()
  • last_type
  • last_value
  • last_traceback
  • maxsize
  • maxunicode
  • meta_path
  • modules
  • path
  • path_hooks
  • path_importer_cache
  • platform
  • prefix
  • ps1
  • ps2
  • setcheckinterval()
  • setdlopenflags()
  • set_int_max_str_digits()
  • setprofile()
  • setrecursionlimit()
  • setswitchinterval()
  • settrace()
  • set_asyncgen_hooks()
  • set_coroutine_wrapper()
  • _enablelegacywindowsfsencoding()
  • stdin
  • stdout
  • stderr
  • __stdin__
  • __stdout__
  • __stderr__
  • thread_info
  • tracebacklimit
  • version
  • api_version
  • version_info
  • warnoptions
  • winver
  • _xoptions
• 29.2. sysconfig — Provide access to Python’s configuration information
  • 29.2.1. Configuration variables
    • get_config_vars()
    • get_config_var()
  • 29.2.2. Installation paths
    • get_scheme_names()
    • get_path_names()
    • get_path()
    • get_paths()
  • 29.2.3. Other functions
    • get_python_version()
    • get_platform()
    • is_python_build()
    • parse_config_h()
    • get_config_h_filename()
    • get_makefile_filename()
  • 29.2.4. Using sysconfig as a script
• 29.3. builtins — Built-in objects
• 29.4. __main__ — Top-level script environment
• 29.5. warnings — Warning control
  • 29.5.1. Warning Categories
  • 29.5.2. The Warnings Filter
    • 29.5.2.1. Default Warning Filters
  • 29.5.3. Temporarily Suppressing Warnings
  • 29.5.4. Testing Warnings
  • 29.5.5. Updating Code For New Versions of Python
  • 29.5.6. Available Functions
    • warn()
    • warn_explicit()
    • showwarning()
    • formatwarning()
    • filterwarnings()
    • simplefilter()
    • resetwarnings()
  • 29.5.7. Available Context Managers
    • catch_warnings
• 29.6. contextlib — Utilities for with-statement contexts
  • 29.6.1. Utilities
    • AbstractContextManager
    • contextmanager()
    • closing()
    • suppress()
    • redirect_stdout()
    • redirect_stderr()
    • ContextDecorator
    • ExitStack
      • ExitStack.enter_context()
      • ExitStack.push()
      • ExitStack.callback()
      • ExitStack.pop_all()
      • ExitStack.close()
  • 29.6.2. Examples and Recipes
    • 29.6.2.1. Supporting a variable number of context managers
    • 29.6.2.2. Simplifying support for single optional context managers
    • 29.6.2.3. Catching exceptions from __enter__ methods
    • 29.6.2.4. Cleaning up in an __enter__ implementation
    • 29.6.2.5. Replacing any use of try-finally and flag variables
    • 29.6.2.6. Using a context manager as a function decorator
  • 29.6.3. Single use, reusable and reentrant context managers
    • 29.6.3.1. Reentrant context managers
    • 29.6.3.2. Reusable context managers
• 29.7. abc — Abstract Base Classes
  • ABC
  • ABCMeta
    • ABCMeta.register()
    • ABCMeta.__subclasshook__()
  • abstractmethod()
  • abstractclassmethod()
  • abstractstaticmethod()
  • abstractproperty()
  • get_cache_token()
• 29.8. atexit — Exit handlers
  • register()
  • unregister()
  • 29.8.1. atexit Example
• 29.9. traceback — Print or retrieve a stack traceback
  • print_tb()
  • print_exception()
  • print_exc()
  • print_last()
  • print_stack()
  • extract_tb()
  • extract_stack()
  • format_list()
  • format_exception_only()
  • format_exception()
  • format_exc()
  • format_tb()
  • format_stack()
  • clear_frames()
  • walk_stack()
  • walk_tb()
  • 29.9.1. TracebackException Objects
    • TracebackException
      • TracebackException.__cause__
      • TracebackException.__context__
      • TracebackException.__suppress_context__
      • TracebackException.stack
      • TracebackException.exc_type
      • TracebackException.filename
      • TracebackException.lineno
      • TracebackException.text
      • TracebackException.offset
      • TracebackException.msg
      • TracebackException.from_exception()
      • TracebackException.format()
      • TracebackException.format_exception_only()
  • 29.9.2. StackSummary Objects
    • StackSummary
      • StackSummary.extract()
      • StackSummary.from_list()
      • StackSummary.format()
  • 29.9.3. FrameSummary Objects
    • FrameSummary
  • 29.9.4. Traceback Examples
• 29.10. __future__ — Future statement definitions
• 29.11. gc — Garbage Collector interface
  • enable()
  • disable()
  • isenabled()
  • collect()
  • set_debug()
  • get_debug()
  • get_objects()
  • get_stats()
  • set_threshold()
  • get_count()
  • get_threshold()
  • get_referrers()
  • get_referents()
  • is_tracked()
  • garbage
  • callbacks
  • DEBUG_STATS
  • DEBUG_COLLECTABLE
  • DEBUG_UNCOLLECTABLE
  • DEBUG_SAVEALL
  • DEBUG_LEAK
• 29.12. inspect — Inspect live objects
  • 29.12.1. Types and members
    • getmembers()
    • getmodulename()
    • ismodule()
    • isclass()
    • ismethod()
    • isfunction()
    • isgeneratorfunction()
    • isgenerator()
    • iscoroutinefunction()
    • iscoroutine()
    • isawaitable()
    • isasyncgenfunction()
    • isasyncgen()
    • istraceback()
    • isframe()
    • iscode()
    • isbuiltin()
    • isroutine()
    • isabstract()
    • ismethoddescriptor()
    • isdatadescriptor()
    • isgetsetdescriptor()
    • ismemberdescriptor()
  • 29.12.2. Retrieving source code
    • getdoc()
    • getcomments()
    • getfile()
    • getmodule()
    • getsourcefile()
    • getsourcelines()
    • getsource()
    • cleandoc()
  • 29.12.3. Introspecting callables with the Signature object
    • signature()
    • Signature
      • Signature.empty
      • Signature.parameters
      • Signature.return_annotation
      • Signature.bind()
      • Signature.bind_partial()
      • Signature.replace()
      • Signature.from_callable()
    • Parameter
      • Parameter.empty
      • Parameter.name
      • Parameter.default
      • Parameter.annotation
      • Parameter.kind
      • Parameter.replace()
    • BoundArguments
      • BoundArguments.arguments
      • BoundArguments.args
      • BoundArguments.kwargs
      • BoundArguments.signature
      • BoundArguments.apply_defaults()
  • 29.12.4. Classes and functions
    • getclasstree()
    • getargspec()
    • getfullargspec()
    • getargvalues()
    • formatargspec()
    • formatargvalues()
    • getmro()
    • getcallargs()
    • getclosurevars()
    • unwrap()
  • 29.12.5. The interpreter stack
    • getframeinfo()
    • getouterframes()
    • getinnerframes()
    • currentframe()
    • stack()
    • trace()
  • 29.12.6. Fetching attributes statically
    • getattr_static()
  • 29.12.7. Current State of Generators and Coroutines
    • getgeneratorstate()
    • getcoroutinestate()
    • getgeneratorlocals()
    • getcoroutinelocals()
  • 29.12.8. Code Objects Bit Flags
    • CO_OPTIMIZED
    • CO_NEWLOCALS
    • CO_VARARGS
    • CO_VARKEYWORDS
    • CO_NESTED
    • CO_GENERATOR
    • CO_NOFREE
    • CO_COROUTINE
    • CO_ITERABLE_COROUTINE
    • CO_ASYNC_GENERATOR
  • 29.12.9. Command Line Interface
• 29.13. site — Site-specific configuration hook
  • 29.13.1. Readline configuration
  • 29.13.2. Module contents
    • PREFIXES
    • ENABLE_USER_SITE
    • USER_SITE
    • USER_BASE
    • main()
    • addsitedir()
    • getsitepackages()
    • getuserbase()
    • getusersitepackages()
• 29.14. fpectl — Floating point exception control
  • turnon_sigfpe()
  • turnoff_sigfpe()
  • FloatingPointError
  • 29.14.1. Example
  • 29.14.2. Limitations and other considerations