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
  • abiflags
  • addaudithook()
  • argv
  • audit()
  • base_exec_prefix
  • base_prefix
  • byteorder
  • builtin_module_names
  • call_tracing()
  • copyright
  • _clear_type_cache()
  • _current_frames()
  • _current_exceptions()
  • breakpointhook()
  • _debugmallocstats()
  • dllhandle
  • displayhook()
  • dont_write_bytecode
  • _emscripten_info
  • pycache_prefix
  • excepthook()
  • __breakpointhook__
  • __displayhook__
  • __excepthook__
  • __unraisablehook__
  • exception()
  • exc_info()
  • exec_prefix
  • executable
  • exit()
  • flags
  • float_info
  • float_repr_style
  • getallocatedblocks()
  • getunicodeinternedsize()
  • getandroidapilevel()
  • getdefaultencoding()
  • getdlopenflags()
  • getfilesystemencoding()
  • getfilesystemencodeerrors()
  • get_int_max_str_digits()
  • getrefcount()
  • getrecursionlimit()
  • getsizeof()
  • getswitchinterval()
  • _getframe()
  • _getframemodulename()
  • getprofile()
  • gettrace()
  • getwindowsversion()
  • get_asyncgen_hooks()
  • get_coroutine_origin_tracking_depth()
  • hash_info
  • hexversion
  • implementation
  • int_info
  • __interactivehook__
  • intern()
  • is_finalizing()
  • last_exc
  • last_type
  • last_value
  • last_traceback
  • maxsize
  • maxunicode
  • meta_path
  • modules
  • orig_argv
  • path
  • path_hooks
  • path_importer_cache
  • platform
  • platlibdir
  • prefix
  • ps1
  • ps2
  • setdlopenflags()
  • set_int_max_str_digits()
  • setprofile()
  • setrecursionlimit()
  • setswitchinterval()
  • settrace()
  • set_asyncgen_hooks()
  • set_coroutine_origin_tracking_depth()
  • activate_stack_trampoline()
  • deactivate_stack_trampoline()
  • is_stack_trampoline_active()
  • _enablelegacywindowsfsencoding()
  • stdin
  • stdout
  • stderr
  • __stdin__
  • __stdout__
  • __stderr__
  • stdlib_module_names
  • thread_info
  • tracebacklimit
  • unraisablehook()
  • version
  • api_version
  • version_info
  • warnoptions
  • winver
  • _xoptions
• sysconfig — Provide access to Python’s configuration information
  • Configuration variables
    • get_config_vars()
    • get_config_var()
  • Installation paths
    • get_scheme_names()
    • get_default_scheme()
    • get_preferred_scheme()
    • _get_preferred_schemes()
    • get_path_names()
    • get_path()
    • get_paths()
  • Other functions
    • get_python_version()
    • get_platform()
    • is_python_build()
    • parse_config_h()
    • get_config_h_filename()
    • get_makefile_filename()
  • Using sysconfig as a script
• 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
    • Describing Warning Filters
    • Default Warning Filter
    • Overriding the default filter
  • Temporarily Suppressing Warnings
  • Testing Warnings
  • Updating Code For New Versions of Dependencies
  • Available Functions
    • warn()
    • warn_explicit()
    • showwarning()
    • formatwarning()
    • filterwarnings()
    • simplefilter()
    • resetwarnings()
  • Available Context Managers
    • catch_warnings
• dataclasses — Data Classes
  • Module contents
    • dataclass()
    • field()
    • Field
    • fields()
    • asdict()
    • astuple()
    • make_dataclass()
    • replace()
    • is_dataclass()
    • MISSING
    • KW_ONLY
    • FrozenInstanceError
  • Post-init processing
    • __post_init__()
  • 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
    • AbstractContextManager
    • AbstractAsyncContextManager
    • contextmanager()
    • asynccontextmanager()
    • closing()
    • aclosing()
    • nullcontext()
    • suppress()
    • redirect_stdout()
    • redirect_stderr()
    • chdir()
    • ContextDecorator
    • AsyncContextDecorator
    • ExitStack
      • ExitStack.enter_context()
      • ExitStack.push()
      • ExitStack.callback()
      • ExitStack.pop_all()
      • ExitStack.close()
    • AsyncExitStack
      • AsyncExitStack.enter_async_context()
      • AsyncExitStack.push_async_exit()
      • AsyncExitStack.push_async_callback()
      • AsyncExitStack.aclose()
  • 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
  • ABC
  • ABCMeta
    • ABCMeta.register()
    • ABCMeta.__subclasshook__()
  • abstractmethod()
  • abstractclassmethod()
  • abstractstaticmethod()
  • abstractproperty()
  • get_cache_token()
  • update_abstractmethods()
• atexit — Exit handlers
  • register()
  • unregister()
  • atexit Example
• 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()
  • TracebackException Objects
    • TracebackException
      • TracebackException.__cause__
      • TracebackException.__context__
      • TracebackException.exceptions
      • TracebackException.__suppress_context__
      • TracebackException.__notes__
      • TracebackException.stack
      • TracebackException.exc_type
      • TracebackException.filename
      • TracebackException.lineno
      • TracebackException.end_lineno
      • TracebackException.text
      • TracebackException.offset
      • TracebackException.end_offset
      • TracebackException.msg
      • TracebackException.from_exception()
      • TracebackException.print()
      • TracebackException.format()
      • TracebackException.format_exception_only()
  • StackSummary Objects
    • StackSummary
      • StackSummary.extract()
      • StackSummary.from_list()
      • StackSummary.format()
      • StackSummary.format_frame_summary()
  • FrameSummary Objects
    • FrameSummary
  • Traceback Examples
• __future__ — Future statement definitions
• 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()
  • is_finalized()
  • freeze()
  • unfreeze()
  • get_freeze_count()
  • garbage
  • callbacks
  • DEBUG_STATS
  • DEBUG_COLLECTABLE
  • DEBUG_UNCOLLECTABLE
  • DEBUG_SAVEALL
  • DEBUG_LEAK
• inspect — Inspect live objects
  • Types and members
    • getmembers()
    • getmembers_static()
    • getmodulename()
    • ismodule()
    • isclass()
    • ismethod()
    • isfunction()
    • isgeneratorfunction()
    • isgenerator()
    • iscoroutinefunction()
    • markcoroutinefunction()
    • iscoroutine()
    • isawaitable()
    • isasyncgenfunction()
    • isasyncgen()
    • istraceback()
    • isframe()
    • iscode()
    • isbuiltin()
    • ismethodwrapper()
    • isroutine()
    • isabstract()
    • ismethoddescriptor()
    • isdatadescriptor()
    • isgetsetdescriptor()
    • ismemberdescriptor()
  • Retrieving source code
    • getdoc()
    • getcomments()
    • getfile()
    • getmodule()
    • getsourcefile()
    • getsourcelines()
    • getsource()
    • cleandoc()
  • 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.kind.description
      • Parameter.replace()
    • BoundArguments
      • BoundArguments.arguments
      • BoundArguments.args
      • BoundArguments.kwargs
      • BoundArguments.signature
      • BoundArguments.apply_defaults()
  • Classes and functions
    • getclasstree()
    • getfullargspec()
    • getargvalues()
    • formatargvalues()
    • getmro()
    • getcallargs()
    • getclosurevars()
    • unwrap()
    • get_annotations()
  • The interpreter stack
    • FrameInfo
      • FrameInfo.frame
      • FrameInfo.filename
      • FrameInfo.lineno
      • FrameInfo.function
      • FrameInfo.code_context
      • FrameInfo.index
      • FrameInfo.positions
    • Traceback
      • Traceback.filename
      • Traceback.lineno
      • Traceback.function
      • Traceback.code_context
      • Traceback.index
      • Traceback.positions
    • getframeinfo()
    • getouterframes()
    • getinnerframes()
    • currentframe()
    • stack()
    • trace()
  • Fetching attributes statically
    • getattr_static()
  • Current State of Generators, Coroutines, and Asynchronous Generators
    • getgeneratorstate()
    • getcoroutinestate()
    • getasyncgenstate()
    • getgeneratorlocals()
    • getcoroutinelocals()
    • getasyncgenlocals()
  • Code Objects Bit Flags
    • CO_OPTIMIZED
    • CO_NEWLOCALS
    • CO_VARARGS
    • CO_VARKEYWORDS
    • CO_NESTED
    • CO_GENERATOR
    • CO_COROUTINE
    • CO_ITERABLE_COROUTINE
    • CO_ASYNC_GENERATOR
  • Buffer flags
    • BufferFlags
      • BufferFlags.SIMPLE
      • BufferFlags.WRITABLE
      • BufferFlags.FORMAT
      • BufferFlags.ND
      • BufferFlags.STRIDES
      • BufferFlags.C_CONTIGUOUS
      • BufferFlags.F_CONTIGUOUS
      • BufferFlags.ANY_CONTIGUOUS
      • BufferFlags.INDIRECT
      • BufferFlags.CONTIG
      • BufferFlags.CONTIG_RO
      • BufferFlags.STRIDED
      • BufferFlags.STRIDED_RO
      • BufferFlags.RECORDS
      • BufferFlags.RECORDS_RO
      • BufferFlags.FULL
      • BufferFlags.FULL_RO
      • BufferFlags.READ
      • BufferFlags.WRITE
  • Command Line Interface
• site — Site-specific configuration hook
  • Readline configuration
  • Module contents
    • PREFIXES
    • ENABLE_USER_SITE
    • USER_SITE
    • USER_BASE
    • main()
    • addsitedir()
    • getsitepackages()
    • getuserbase()
    • getusersitepackages()
  • Command Line Interface