29.1. `sys` — 特定系统参数和函数 ¶

此模块提供对由解释器使用或维护的一些变量的访问，及对与解释器强交互函数的访问。它始终可用。

sys. abiflags ¶

sys. argv ¶

sys. base_exec_prefix ¶

sys. base_prefix ¶

sys. byteorder ¶

sys. builtin_module_names ¶

sys. call_tracing ( func , args ) ¶

sys. copyright ¶

sys. _clear_type_cache ( ) ¶

sys. _current_frames ( ) ¶

sys. _debugmallocstats ( ) ¶

sys. dllhandle ¶

sys. displayhook ( value ) ¶

sys. dont_write_bytecode ¶

sys. excepthook ( type , value , traceback ) ¶

sys. __displayhook__ ¶
sys. __excepthook__ ¶

sys. exc_info ( ) ¶

sys. exec_prefix ¶

sys. executable ¶

sys. exit ( [ arg ] ) ¶

sys. flags ¶

属性	flag
`debug`	`-d`
`inspect`	`-i`
`interactive`	`-i`
`optimize`	`-O` or `-OO`
`dont_write_bytecode`	`-B`
`no_user_site`	`-s`
`no_site`	`-S`
`ignore_environment`	`-E`
`verbose`	`-v`
`bytes_warning`	`-b`
`quiet`	`-q`
`hash_randomization`	`-R`

sys. float_info ¶

属性	float.h 宏	解释
`epsilon`	DBL_EPSILON	difference between 1 and the least value greater than 1 that is representable as a float
`dig`	DBL_DIG	maximum number of decimal digits that can be faithfully represented in a float; see below
`mant_dig`	DBL_MANT_DIG	float precision: the number of base- `radix` digits in the significand of a float
`max`	DBL_MAX	maximum representable finite float
`max_exp`	DBL_MAX_EXP	maximum integer e such that `radix**(e-1)` is a representable finite float
`max_10_exp`	DBL_MAX_10_EXP	maximum integer e such that `10**e` is in the range of representable finite floats
`min`	DBL_MIN	最小正规范化浮点
`min_exp`	DBL_MIN_EXP	minimum integer e such that `radix**(e-1)` is a normalized float
`min_10_exp`	DBL_MIN_10_EXP	minimum integer e such that `10**e` 是 normalized float
`radix`	FLT_RADIX	表示指数的基数
`rounds`	FLT_ROUNDS	integer constant representing the rounding mode used for arithmetic operations. This reflects the value of the system FLT_ROUNDS macro at interpreter startup time. See section 5.2.4.2.2 of the C99 standard for an explanation of the possible values and their meanings.

sys. float_repr_style ¶

sys. getallocatedblocks ( ) ¶

sys. getcheckinterval ( ) ¶

sys. getdefaultencoding ( ) ¶: Return the name of the current default string encoding used by the Unicode implementation.

sys. getdlopenflags ( ) ¶: Return the current value of the flags that are used for dlopen() calls. Symbolic names for the flag values can be found in the os 模块 ( RTLD_xxx constants, e.g. os.RTLD_LAZY ). Availability: Unix.

sys. getfilesystemencoding ( ) ¶

Return the name of the encoding used to convert Unicode filenames into system file names. The result value depends on the operating system:

在 Mac OS X，编码是 'utf-8' .
On Unix, the encoding is the user’s preference according to the result of nl_langinfo(CODESET).
On Windows NT+, file names are Unicode natively, so no conversion is performed. getfilesystemencoding() still returns 'mbcs' , as this is the encoding that applications should use when they explicitly want to convert Unicode strings to byte strings that are equivalent when used as file names.
On Windows 9x, the encoding is 'mbcs' .

3.2 版改变： getfilesystemencoding() 结果不可以是 None 不再。

sys. getrefcount ( object ) ¶: 返回引用计数为 object 。一般来说，返回计数可能比期望大 1，因为它包含 (临时) 引用作为自变量在 getrefcount() .

sys. getrecursionlimit ( ) ¶: 返回递归限制的当前值 (Python 解释器堆栈的最大深度)。此限制阻止导致 C 堆栈溢出和 Python 崩溃的无限递归。可以设置它通过 setrecursionlimit() .

sys. getsizeof ( object [ , default ] ) ¶

返回对象的大小，以字节为单位。对象可以是任何类型的对象。所有内置对象会返回正确结果，但对于第 3 方扩展而言这不一定正确，因为它是特定实现。

Only the memory consumption directly attributed to the object is accounted for, not the memory consumption of objects it refers to.

若给定， default will be returned if the object does not provide means to retrieve the size. Otherwise a TypeError 会被引发。

getsizeof() 调用对象的 __sizeof__ method and adds an additional garbage collector overhead if the object is managed by the garbage collector.

见递归大小配方例如使用 getsizeof() 递归查找容器大小及其所有内容。

sys. getswitchinterval ( ) ¶

返回解释器的 "线程切换间隔"；见 setswitchinterval() .

3.2 版新增。

sys. _getframe ( [ depth ] ) ¶

从调用堆栈返回帧对象。若可选整数 depth 有给定，返回堆栈顶部下多个调用帧对象。若比调用堆栈更深， ValueError 被引发。默认 depth 为 0，返回调用堆栈顶部帧。

CPython 实现细节： 此函数只应用于内部和专用目的。它不保证在所有 Python 实现中均存在。

sys. getprofile ( ) ¶: 获取剖分析器函数如设置通过 setprofile() .

sys. gettrace ( ) ¶

获取跟踪函数如设置通过 settrace() .

CPython 实现细节： The gettrace() function is intended only for implementing debuggers, profilers, coverage tools and the like. Its behavior is part of the implementation platform, rather than part of the language definition, and thus may not be available in all Python implementations.

sys. getwindowsversion ( ) ¶

Return a named tuple describing the Windows version currently running. The named elements are major , minor , build , platform , service_pack , service_pack_minor , service_pack_major , suite_mask ，和 product_type . service_pack contains a string while all other values are integers. The components can also be accessed by name, so sys.getwindowsversion()[0] 相当于 sys.getwindowsversion().major . For compatibility with prior versions, only the first 5 elements are retrievable by indexing.

platform may be one of the following values:

常量	平台
`0 (VER_PLATFORM_WIN32s)`	Win32s on Windows 3.1
`1 (VER_PLATFORM_WIN32_WINDOWS)`	Windows 95/98/ME
`2 (VER_PLATFORM_WIN32_NT)`	Windows NT/2000/XP/x64
`3 (VER_PLATFORM_WIN32_CE)`	Windows CE

product_type may be one of the following values:

常量	含义
`1 (VER_NT_WORKSTATION)`	系统是工作站。
`2 (VER_NT_DOMAIN_CONTROLLER)`	The system is a domain controller.
`3 (VER_NT_SERVER)`	The system is a server, but not a domain controller.

此函数包裹 Win32 GetVersionEx() function; see the Microsoft documentation on OSVERSIONINFOEX() for more information about these fields.

可用性：Windows。

3.2 版改变： Changed to a named tuple and added service_pack_minor , service_pack_major , suite_mask ，和 product_type .

sys. get_coroutine_wrapper ( ) ¶

返回 None , or a wrapper set by set_coroutine_wrapper() .

3.5 版新增：见 PEP 492 了解更多细节。

注意

此函数已添加到暂行基础 (见 PEP 411 了解细节)。仅用于调试目的。

sys. hash_info ¶

A 结构序列 giving parameters of the numeric hash implementation. For more details about hashing of numeric types, see 数值类型的哈希 .

属性	解释
`width`	width in bits used for hash values
`modulus`	prime modulus P used for numeric hash scheme
`inf`	hash value returned for a positive infinity
`nan`	hash value returned for a nan
`imag`	multiplier used for the imaginary part of a 复数
`algorithm`	name of the algorithm for hashing of str, bytes, and memoryview
`hash_bits`	internal output size of the hash algorithm
`seed_bits`	size of the seed key of the hash algorithm

3.2 版新增。

3.4 版改变：添加 algorithm , hash_bits and seed_bits

sys. hexversion ¶

The version number encoded as a single integer. This is guaranteed to increase with each version, including proper support for non-production releases. For example, to test that the Python interpreter is at least version 1.5.2, use:

if sys.hexversion >= 0x010502F0:
    # use some advanced feature
    ...
else:
    # use an alternative implementation or warn the user
    ...

This is called hexversion since it only really looks meaningful when viewed as the result of passing it to the built-in hex() 函数。结构序列 sys.version_info may be used for a more human-friendly encoding of the same information.

更多细节对于 hexversion 可以找到在 API 和 ABI 版本控制 .

sys. implementation ¶

包含目前运行 Python 解释器实现有关信息的对象。下列属性被要求存在于所有 Python 实现中。

name 是实现的标识符，如 'cpython' 。实际字符串由 Python 实现定义，但它保证是小写。

version is a named tuple, in the same format as sys.version_info . It represents the version of the Python 实现 . This has a distinct meaning from the specific version of the Python 语言 to which the currently running interpreter conforms, which sys.version_info represents. For example, for PyPy 1.8 sys.implementation.version 可以是 sys.version_info(1, 8, 0, 'final', 0) ，而 sys.version_info 将为 sys.version_info(2, 7, 2, 'final', 0) . For CPython they are the same value, since it is the reference implementation.

hexversion is the implementation version in hexadecimal format, like sys.hexversion .

cache_tag is the tag used by the import machinery in the filenames of cached modules. By convention, it would be a composite of the implementation’s name and version, like 'cpython-33' . However, a Python implementation may use some other value if appropriate. If cache_tag 被设为 None , it indicates that module caching should be disabled.

sys.implementation may contain additional attributes specific to the Python implementation. These non-standard attributes must start with an underscore, and are not described here. Regardless of its contents, sys.implementation will not change during a run of the interpreter, nor between implementation versions. (It may change between Python language versions, however.) See PEP 421 了解更多信息。

3.3 版新增。

sys. int_info ¶

A 结构序列 that holds information about Python’s internal representation of integers. The attributes are read only.

属性	解释
`bits_per_digit`	number of bits held in each digit. Python integers are stored internally in base `2**int_info.bits_per_digit`
`sizeof_digit`	size in bytes of the C type used to represent a digit

3.1 版新增。

sys. __interactivehook__ ¶

When this attribute exists, its value is automatically called (with no arguments) when the interpreter is launched in 交互模式 . This is done after the PYTHONSTARTUP file is read, so that you can set this hook there. The site 模块 sets this .

3.4 版新增。

sys. intern ( string ) ¶

Enter string in the table of “interned” strings and return the interned string – which is string itself or a copy. Interning strings is useful to gain a little performance on dictionary lookup – if the keys in a dictionary are interned, and the lookup key is interned, the key comparisons (after hashing) can be done by a pointer compare instead of a string compare. Normally, the names used in Python programs are automatically interned, and the dictionaries used to hold module, class or instance attributes have interned keys.

Interned strings are not immortal; you must keep a reference to the return value of intern() around to benefit from it.

sys. is_finalizing ( ) ¶

返回 True 若 Python 解释器是关闭 , False 否则。

3.5 版新增。

sys. last_type ¶

sys. last_value ¶

sys. last_traceback ¶

These three variables are not always defined; they are set when an exception is not handled and the interpreter prints an error message and a stack traceback. Their intended use is to allow an interactive user to import a debugger module and engage in post-mortem debugging without having to re-execute the command that caused the error. (Typical use is import pdb; pdb.pm() to enter the post-mortem debugger; see pdb module for more information.)

The meaning of the variables is the same as that of the return values from exc_info() above.

sys. maxsize ¶: An integer giving the maximum value a variable of type Py_ssize_t can take. It’s usually 2**31 - 1 在 32 位平台和 2**63 - 1 在 64 位平台。

sys. maxunicode ¶

An integer giving the value of the largest Unicode code point, i.e. 1114111 ( 0x10FFFF in hexadecimal).

3.3 版改变： Before PEP 393 , sys.maxunicode used to be either 0xFFFF or 0x10FFFF , depending on the configuration option that specified whether Unicode characters were stored as UCS-2 or UCS-4.

sys. meta_path ¶

列表化的元路径查找器对象拥有 find_spec() methods called to see if one of the objects can find the module to be imported. The find_spec() method is called with at least the absolute name of the module being imported. If the module to be imported is contained in a package, then the parent package’s __path__ attribute is passed in as a second argument. The method returns a 模块特定，或 None if the module cannot be found.

另请参阅

importlib.abc.MetaPathFinder: The abstract base class defining the interface of finder objects on meta_path .
importlib.machinery.ModuleSpec: 具体类 find_spec() should return instances of.

3.4 版改变：模块特定在 Python 3.4 引入，由 PEP 451 。早期版本的 Python 查找方法称为 find_module() 。这仍被称为回退若 meta_path 条目没有 find_spec() 方法。

sys. modules ¶: 这是将模块名称映射到已加载模块的字典。这可以被操纵以强制重新加载模块及其它技巧。不管怎样，替换字典必然不按预期工作，且从字典删除必需项可能导致 Python 失败。

sys. path ¶

指定模块搜索路径的字符串列表。初始化自环境变量 PYTHONPATH ，加从属安装默认。

在程序启动时被初始化，此列表的第一项， path[0] , is the directory containing the script that was used to invoke the Python interpreter. If the script directory is not available (e.g. if the interpreter is invoked interactively or if the script is read from standard input), path[0] is the empty string, which directs Python to search modules in the current directory first. Notice that the script directory is inserted before 插入条目作为结果对于 PYTHONPATH .

A program is free to modify this list for its own purposes. Only strings and bytes should be added to sys.path ; all other data types are ignored during import.

另请参阅

模块 site 这描述如何使用 .pth 文件扩展 sys.path .

sys. path_hooks ¶

A list of callables that take a path argument to try to create a finder for the path. If a finder can be created, it is to be returned by the callable, else raise ImportError .

最初的指定在 PEP 302 .

sys. path_importer_cache ¶

字典充当缓存对于 finder objects. The keys are paths that have been passed to sys.path_hooks and the values are the finders that are found. If a path is a valid file system path but no finder is found on sys.path_hooks then None 是存储。

最初的指定在 PEP 302 .

3.3 版改变： None 被存储而不是 imp.NullImporter 当找不到查找器时。

sys. platform ¶

This string contains a platform identifier that can be used to append platform-specific components to sys.path ，例如。

For Unix systems, except on Linux, this is the lowercased OS name as returned by uname -s with the first part of the version as returned by uname -r appended, e.g. 'sunos5' or 'freebsd8' , at the time when Python was built . Unless you want to test for a specific system version, it is therefore recommended to use the following idiom:

if sys.platform.startswith('freebsd'):
    # FreeBSD-specific code here...
elif sys.platform.startswith('linux'):
    # Linux-specific code here...

对于其它系统，值是：

系统	`platform` 值
Linux	`'linux'`
Windows	`'win32'`
Windows/Cygwin	`'cygwin'`
Mac OS X	`'darwin'`

3.3 版改变：在 Linux， sys.platform 不再包含主要版本。它始终是 'linux' ，而不是 'linux2' or 'linux3' . Since older Python versions include the version number, it is recommended to always use the startswith idiom presented above.

另请参阅

os.name 拥有更粗的粒度。 os.uname() 给出系统从属版本信息。

The platform 模块提供系统身份的详细校验。

sys. prefix ¶

A string giving the site-specific directory prefix where the platform independent Python files are installed; by default, this is the string '/usr/local' . This can be set at build time with the --prefix 自变量到 configure script. The main collection of Python library modules is installed in the directory prefix/lib/pythonX.Y while the platform independent header files (all except pyconfig.h ) are stored in prefix/include/pythonX.Y ，其中 X.Y is the version number of Python, for example 3.2 .

注意

若虚拟环境 is in effect, this value will be changed in site.py to point to the virtual environment. The value for the Python installation will still be available, via base_prefix .

sys. ps1 ¶
sys. ps2 ¶: Strings specifying the primary and secondary prompt of the interpreter. These are only defined if the interpreter is in interactive mode. Their initial values in this case are '>>> ' and '... ' . If a non-string object is assigned to either variable, its str() is re-evaluated each time the interpreter prepares to read a new interactive command; this can be used to implement a dynamic prompt.

sys. setcheckinterval ( interval ) ¶

设置解释器的 "检查间隔"。此整数值确定解释器检查周期性事物 (譬如：线程切换和信号处理程序) 的频率。默认为 100 ，意味着每隔 100 条 Python 虚拟指令履行一次检查。将它设为较大值，可以提高使用线程的程序性能。将它设为值 <= 0 检查每条虚拟指令，最大化响应速度及开销。

从 3.2 版起弃用：此函数不再起作用，因为线程切换和异步任务的内部逻辑已被重写。使用 setswitchinterval() 代替。

sys. setdlopenflags ( n ) ¶

Set the flags used by the interpreter for dlopen() calls, such as when the interpreter loads extension modules. Among other things, this will enable a lazy resolving of symbols when importing a module, if called as sys.setdlopenflags(0) . To share symbols across extension modules, call as sys.setdlopenflags(os.RTLD_GLOBAL) . Symbolic names for the flag values can be found in the os 模块 ( RTLD_xxx constants, e.g. os.RTLD_LAZY ).

可用性：Unix。

sys. setprofile ( profilefunc ) ¶: Set the system’s profile function, which allows you to implement a Python source code profiler in Python. See chapter Python 剖分析器 for more information on the Python profiler. The system’s profile function is called similarly to the system’s trace function (see settrace() ), but it isn’t called for each executed line of code (only on call and return, but the return event is reported even when an exception has been set). The function is thread-specific, but there is no way for the profiler to know about context switches between threads, so it does not make sense to use this in the presence of multiple threads. Also, its return value is not used, so it can simply return None .

sys. setrecursionlimit ( limit ) ¶

将 Python 解释器堆栈的最大深度设为 limit 。此限制阻止导致 C 堆栈溢出和 Python 崩溃的无限递归。

可能的最高限制从属平台。用户可能需要将限制设置得更高，当程序要求深入递归且平台支持更高限制时。应该小心这样做，因为过高的限制可能导致崩溃。

若当前递归深度的新限制过低， RecursionError 异常被引发。

3.5.1 版改变： A RecursionError 异常现在引发，若新限制在当前递归深度处太低。

sys. setswitchinterval ( interval ) ¶

设置解释器的线程切换间隔 (以秒为单位)。此浮点值确定分配给并发运行 Python 线程的 "时间切片" 的理想持续时间。请注意，实际值可以更高，尤其是使用长时间运行内部函数或方法。另外，间隔结束时变为调度哪个线程，由操作系统决策。解释器没有自己的调度器。

3.2 版新增。

sys. settrace ( tracefunc ) ¶

Set the system’s trace function, which allows you to implement a Python source code debugger in Python. The function is thread-specific; for a debugger to support multiple threads, it must be registered using settrace() for each thread being debugged.

Trace functions should have three arguments: frame , event ，和 arg . frame is the current stack frame. event is a string: 'call' , 'line' , 'return' , 'exception' , 'c_call' , 'c_return' ，或 'c_exception' . arg depends on the event type.

跟踪函数是援引 (采用 event 设为 'call' ) whenever a new local scope is entered; it should return a reference to a local trace function to be used that scope, or None if the scope shouldn’t be traced.

The local trace function should return a reference to itself (or to another function for further tracing in that scope), or None to turn off tracing in that scope.

事件拥有下列含义：

'call': A function is called (or some other code block entered). The global trace function is called; arg is None ; the return value specifies the local trace function.
'line': The interpreter is about to execute a new line of code or re-execute the condition of a loop. The local trace function is called; arg is None ; the return value specifies the new local trace function. See Objects/lnotab_notes.txt for a detailed explanation of how this works.
'return': A function (or other code block) is about to return. The local trace function is called; arg is the value that will be returned, or None if the event is caused by an exception being raised. The trace function’s return value is ignored.
'exception': 出现异常。调用局部跟踪函数； arg 是 tuple (exception, value, traceback) ; the return value specifies the new local trace function.
'c_call': A C function is about to be called. This may be an extension function or a built-in. arg 是 C 函数对象。
'c_return': A C function has returned. arg 是 C 函数对象。
'c_exception': C 函数引发异常。 arg 是 C 函数对象。

注意，由于异常沿调用者链向下传播， 'exception' 事件会在每级生成。

For more information on code and frame objects, refer to 标准类型层次结构 .

CPython 实现细节： The settrace() function is intended only for implementing debuggers, profilers, coverage tools and the like. Its behavior is part of the implementation platform, rather than part of the language definition, and thus may not be available in all Python implementations.

sys. settscdump ( on_flag ) ¶

Activate dumping of VM measurements using the Pentium timestamp counter, if on_flag is true. Deactivate these dumps if on_flag is off. The function is available only if Python was compiled with --with-tsc . To understand the output of this dump, read Python/ceval.c in the Python sources.

CPython 实现细节： This function is intimately bound to CPython implementation details and thus not likely to be implemented elsewhere.

sys. set_coroutine_wrapper ( wrapper ) ¶

允许拦截创建的协程 objects (only ones that are created by an async def function; generators decorated with types.coroutine() or asyncio.coroutine() will not be intercepted).

The wrapper 自变量必须是：

a callable that accepts one argument (a coroutine object);
None , to reset the wrapper.

If called twice, the new wrapper replaces the previous one. The function is thread-specific.

The wrapper callable cannot define new coroutines directly or indirectly:

def wrapper(coro):
    async def wrap(coro):
        return await coro
    return wrap(coro)
sys.set_coroutine_wrapper(wrapper)
async def foo():
    pass
# The following line will fail with a RuntimeError, because
# ``wrapper`` creates a ``wrap(coro)`` coroutine:
foo()

另请参阅 get_coroutine_wrapper() .

3.5 版新增：见 PEP 492 了解更多细节。

注意

此函数已添加到暂行基础 (见 PEP 411 了解细节)。仅用于调试目的。

sys. stdin ¶

sys. stdout ¶

sys. stderr ¶

文件对象用于解释器为标准输入、标准输出及标准错误：

stdin 用于所有交互输入 (包括调用 input() );
stdout 用于输出源自 print() and 表达式语句及提示对于 input() ;
解释器自己的提示及其错误消息转到 stderr .

这些流是常规文本文件像那些返回通过 open() 函数。它们参数的选取如下：

The character encoding is platform-dependent. Under Windows, if the stream is interactive (that is, if its isatty() 方法返回 True ), the console codepage is used, otherwise the ANSI code page. Under other platforms, the locale encoding is used (see locale.getpreferredencoding() ).

Under all platforms though, you can override this value by setting the PYTHONIOENCODING environment variable before starting Python.
When interactive, standard streams are line-buffered. Otherwise, they are block-buffered like regular text files. You can override this value with the -u command-line option.

注意

要写入 (或读取) 二进制数据从/到标准流，使用底层二进制 buffer 对象。例如：要写入 bytes 到 stdout ，使用 sys.stdout.buffer.write(b'abc') .

不管怎样，若正编写库 (且不控制其代码在上下文中的执行)，注意，标准流可能被替换为像文件对象，如 io.StringIO 不支持 buffer 属性。

sys. __stdin__ ¶

sys. __stdout__ ¶

sys. __stderr__ ¶

这些对象包含原始值的 stdin , stderr and stdout 当程序启动时。在定稿期间使用它们，可以打印到实际标准流不管是否 sys.std* 对象已被重定向。

还可以用于将实际文件还原到已知工作文件对象，若它们被破坏对象所覆写。不管怎样，首选方式是在替换它之前明确保存先前流，再还原保存对象。

注意

在某些条件下 stdin , stdout and stderr 及原始值 __stdin__ , __stdout__ and __stderr__ 可以是 None 。通常是这种情况，对于未连接到控制台的 Windows GUI APP 和 Python APP 启动采用 pythonw .

sys. thread_info ¶

A 结构序列保持线程实现的有关信息。

属性解释

属性	解释
`name`	线程实现的名称： `'nt'` ：Windows 线程 `'pthread'` ：POSIX 线程 `'solaris'` ：Solaris 线程
`lock`	锁实现的名称： `'semaphore'` ：锁使用信号量 `'mutex+cond'` : a lock uses a mutex and a condition variable `None` 如果此信息未知
`version`	Name and version of the thread library. It is a string, or `None` 若此信息未知。


name

线程实现的名称：

'nt' ：Windows 线程

'pthread' ：POSIX 线程

'solaris' ：Solaris 线程


lock

锁实现的名称：

'semaphore' ：锁使用信号量

'mutex+cond' : a lock uses a mutex and a condition variable

None 如果此信息未知

version Name and version of the thread library. It is a string, or None 若此信息未知。

3.3 版新增。

sys. tracebacklimit ¶

sys. version ¶: A string containing the version number of the Python interpreter plus additional information on the build number and compiler used. This string is displayed when the interactive interpreter is started. Do not extract version information out of it, rather, use version_info and the functions provided by the platform 模块。

sys. api_version ¶: The C API version for this interpreter. Programmers may find this useful when debugging version conflicts between Python and extension modules.

sys. version_info ¶

包含版本编号 5 分量的元组： major , minor , micro , releaselevel ，和 serial 。所有值除了 releaselevel 都是整数；releaselevel 为 'alpha' , 'beta' , 'candidate' ，或 'final' 。 version_info value corresponding to the Python version 2.0 is (2, 0, 0, 'final', 0) . The components can also be accessed by name, so sys.version_info[0] 相当于 sys.version_info.major 依此类推。

3.1 版改变：添加命名组件属性。

sys. warnoptions ¶: This is an implementation detail of the warnings framework; do not modify this value. Refer to the warnings module for more information on the warnings framework.

sys. winver ¶: The version number used to form registry keys on Windows platforms. This is stored as string resource 1000 in the Python DLL. The value is normally the first three characters of version . It is provided in the sys module for informational purposes; modifying this value has no effect on the registry keys used by Python. Availability: Windows.

sys. _xoptions ¶

各种特定实现标志的字典传递透过 -X 命令行选项。选项名要么映射到它们的值 (若明确给定)，要么映射到 True 。范例：

$ ./python -Xa=b -Xc
Python 3.2a3+ (py3k, Oct 16 2010, 20:14:50)
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys._xoptions
{'a': 'b', 'c': True}

CPython 实现细节： This is a CPython-specific way of accessing options passed through -X . Other implementations may export them through other means, or not at all.

3.2 版新增。

引文

[C99]

ISO/IEC 9899:1999. “Programming languages – C.” A public draft of this standard is available at http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf .

上一话题

29. Python 运行时服务

下一话题

29.2. sysconfig — 提供对 Python 配置信息的访问

29.1. sys — 特定系统参数和函数 ¶

上一话题

下一话题

本页

29.1. `sys` — 特定系统参数和函数 ¶