tornado.util — General-purpose utilities¶

Miscellaneous utility functions and classes.

This module is used internally by Tornado. It is not necessarily expectedthat the functions and classes defined here will be useful to otherapplications, but they are documented here in case they are.

The one public-facing part of this module is the Configurable classand its configure method, which becomes a part of theinterface of its subclasses, including AsyncHTTPClient, IOLoop,and Resolver.

class tornado.util.ObjectDict[源代码]

Makes a dictionary behave like an object, with attribute-style access.
class tornado.util.GzipDecompressor[源代码]

Streaming gzip decompressor.

The interface is like that of zlib.decompressobj (without some of theoptional arguments, but it understands gzip headers and checksums.
decompress(value, max_length=None)[源代码]

Decompress a chunk, returning newly-available data.

Some data may be buffered for later processing; flush mustbe called when there is no more input data to ensure thatall data was processed.

If maxlength is given, some input data may be left overin unconsumed_tail; you must retrieve this value and passit back to a future call to decompress if it is not empty.
unconsumed_tail

Returns the unconsumed portion left over
flush()[源代码]

Return any remaining buffered data not yet returned by decompress.

Also checks for errors such as truncated input.No other methods may be called on this object after flush.
tornado.util.import_object(_name)[源代码]

Imports an object by name.

importobject(‘x’) is equivalent to ‘import x’.import_object(‘x.y.z’) is equivalent to ‘from x.y import z’.



  1. >>> import tornado.escape
    >>> import_object('tornado.escape') is tornado.escape
    True
    >>> import_object('tornado.escape.utf8') is tornado.escape.utf8
    True
    >>> import_object('tornado') is tornado
    True
    >>> import_object('tornado.missing_module')
    Traceback (most recent call last):
        …
    ImportError: No module named missing_module



tornado.util.errno_from_exception(_e)[源代码]

Provides the errno from an Exception object.

There are cases that the errno attribute was not set so we pullthe errno out of the args but if someone instantiates an Exceptionwithout any args you will get a tuple error. So this functionabstracts all that behavior to give you a safe way to get theerrno.
tornado.util.reunescape(_s)[源代码]

Unescape a string escaped by re.escape.

May raise ValueError for regular expressions which could nothave been produced by re.escape (for example, strings containing\d cannot be unescaped).


4.4 新版功能.

class tornado.util.Configurable[源代码]

Base class for configurable interfaces.

A configurable interface is an (abstract) class whose constructoracts as a factory function for one of its implementation subclasses.The implementation subclass as well as optional keyword arguments toits initializer can be set globally at runtime with configure.

By using the constructor as the factory method, the interfacelooks like a normal class, isinstance works as usual, etc. Thispattern is most useful when the choice of implementation is likelyto be a global decision (e.g. when epoll is available,always use it instead of select), or when apreviously-monolithic class has been split into specializedsubclasses.

Configurable subclasses must define the class methodsconfigurable_base and configurable_default, and use the instancemethod initialize instead of init.
classmethod configurablebase()[源代码]

Returns the base class of a configurable hierarchy.

This will normally return the class in which it is defined.(which is _not necessarily the same as the cls classmethod parameter).
classmethod configurabledefault()[源代码]

Returns the implementation class to be used if none is configured.
initialize()[源代码]

Initialize a Configurable subclass instance.

Configurable classes should use initialize instead of init.


在 4.2 版更改: Now accepts positional arguments in addition to keyword arguments.

_classmethod configure(impl, **kwargs)[源代码]

Sets the class to use when the base class is instantiated.

Keyword arguments will be saved and added to the arguments passedto the constructor. This can be used to set global defaults forsome parameters.
classmethod configuredclass()[源代码]

Returns the currently configured class.
_class tornado.util.ArgReplacer(func, name)[源代码]

Replaces one value in an args, kwargs pair.

Inspects the function signature to find an argument by namewhether it is passed by position or keyword. For use in decoratorsand similar wrappers.
getold_value(_args, kwargs, default=None)[源代码]

Returns the old value of the named argument without replacing it.

Returns default if the argument is not present.
replace(new_value, args, kwargs)[源代码]

Replace the named argument in args, kwargs with newvalue.

Returns (old_value, args, kwargs). The returned args andkwargs objects may not be the same as the input objects, orthe input objects may be mutated.

If the named argument was not found, new_value will be addedto kwargs and None will be returned as old_value.
tornado.util.timedelta_to_seconds(_td)[源代码]

Equivalent to td.total_seconds() (introduced in python 2.7).

原文:

https://tornado-zh-cn.readthedocs.io/zh_CN/latest/util.html