Python Runtime Services
_builtin_
builtin/builtins - Built-in functions, exceptions, and other objects.
python2叫__builtin__
python3叫builtins
_main_
main - Top-level script environment.
if __name__ == "__main__":
main()
当作为顶层脚本运行时(main), 当作为一个模块运行时候就是模块名称．
_future_
把下一个版本的新特性导入到当前版本。
from __future__ import <feature_name>
# feature name:
all_feature_names # 一次导入所有feature
absolute_import # 绝对导入
division
generators
nested_scopes
print_function
unicode_literals # python2中u'string'才表示unicode, 'string'表示str，python3中所有字符串都是unicode。
with_statement
data:
all_feature_names
...
sys
import sys
Dynamic objects:
# 动态对象
sys.argv # 命令行参数的列表，sys.argv[0]是程序名称, len(sys.argv)就是C语言中的argc
sys.path # 搜索的路径．import导入模块的搜索路径．
sys.modules # 字典格式的加载的模块.已经导入并加载的模块会加进来．
sys.stdin # 标准输入，用于input()
sys.stdout # 标准输出，用于print
sys.stderr # 标准出错
displayhook -- called to show results in an interactive session
excepthook --
last_type -- type of last uncaught exception
last_value -- value of last uncaught exception
last_traceback --
Static objects:
# 静态对象
float_info -- a dict with information about the float inplementation.
long_info -- a struct sequence with information about the long implementation.
maxint -- the largest supported integer (the smallest is -maxint-1).
maxsize -- the largest supported length of containers.
maxunicode -- the largest supported character
builtin_module_names -- tuple of module names built into this interpreter
version -- the version of this interpreter as a string
version_info -- version information as a named tuple
hexversion -- version information encoded as a single integer
copyright -- copyright notice pertaining to this interpreter
platform -- platform identifier # 可以判断操作系统类型
sys.platform # 'win32', 'linux2', 'darwin'
executable -- absolute path of the executable binary of the Python interpreter
prefix -- prefix used to find the Python library
exec_prefix -- prefix used to find the machine-specific Python library
float_repr_style -- string indicating the style of repr() output for floats
__stdin__ -- the original stdin; don't touch!
__stdout__ -- the original stdout; don't touch!
__stderr__ -- the original stderr; don't touch!
__displayhook__ -- the original displayhook; don't touch!
__excepthook__ -- the original excepthook; don't touch!
functions:
displayhook() -- print an object to the screen, and save it in __builtin__._
excepthook() -- print an exception and its traceback to sys.stderr
exc_info() -- 返回当前异常的线程安全的三个信息．type, value, traceback.
exc_clear() -- 清空当前线程的异常状态
exit() -- 抛出 SystemExit 异常退出解释器
getdlopenflags() -- returns flags to be used for dlopen() calls
getprofile() -- get the global profiling function
getrefcount() -- return the reference count for an object (plus one :-)
getrecursionlimit() -- return the max recursion depth for the interpreter
getsizeof() -- return the size of an object in bytes
gettrace() -- get the global debug tracing function
setcheckinterval() -- control how often the interpreter checks for events
setdlopenflags() -- set the flags to be used for dlopen() calls
setprofile() -- set the global profiling function
setrecursionlimit() -- set the max recursion depth for the interpreter
settrace() -- set the global debug tracing function
data:
flags # 命令行的状态，-d debug, -v verbose
sysconfig
future_builtins
warnings
python的警告模块，只警告，不中断程序运行．
import warnings
functions:
warn(message[, category[, stacklevel]])
contextlib
编写上下文管理器的模块．
import contextlib
abc
实现抽象方法．
import abc
classes:
# abc.ABCMeta
ABCMeta
# abc.abstractproperty
abstractproperty
functions:
abstractmethod(funcobj)
atexit
traceback
For python stack traces. 追踪python的堆栈信息．
import traceback
functions:
extract_stack(f=None, limit=None)
extract_tb(tb, limit=None)
format_stack(f=None, limit=None)
format_tb(tb, limit=None) # 格式化后返回字符串
print_stack(f=None, limit=None, file=None)
print_tb(tb, limit=None, file=None) # 直接打印stacktrace信息
...
gc
garbage collector：python的垃圾回收模块．
import gc
inspect
从运行的python对象获取有用的信息．
import inspect
classes:
functions:
classify_class_attrs(cls)
stack(context=1)
isgenerator()
isgeneratorfunction() # 检查一个函数是否是生成器
data: