repr
— 替代
repr()
实现
¶
注意
The
repr
module has been renamed to
reprlib
in Python 3. The
2to3
tool will automatically adapt imports when converting your sources to Python 3.
源代码： Lib/repr.py
The
repr
module provides a means for producing object representations with limits on the size of the resulting strings. This is used in the Python debugger and may be useful in other contexts as well.
This module provides a class, an instance, and a function:
repr.
Repr
¶
Class which provides formatting services useful in implementing functions similar to the built-in repr() ; size limits for different object types are added to avoid the generation of representations which are excessively long.
repr.
aRepr
¶
This is an instance of
Repr
which is used to provide the
repr()
function described below. Changing the attributes of this object will affect the size limits used by
repr()
and the Python debugger.
repr.
repr
(
obj
)
¶
这是
repr()
方法为
aRepr
. It returns a string similar to that returned by the built-in function of the same name, but with limits on most sizes.
Repr
instances provide several attributes which can be used to provide size limits for the representations of different object types, and methods which format specific object types.
Repr.
maxlevel
¶
Depth limit on the creation of recursive representations. The default is
6
.
Repr.
maxdict
¶
Repr.
maxlist
¶
Repr.
maxtuple
¶
Repr.
maxset
¶
Repr.
maxfrozenset
¶
Repr.
maxdeque
¶
Repr.
maxarray
¶
Limits on the number of entries represented for the named object type. The default is
4
for
maxdict
,
5
for
maxarray
，和
6
for the others.
New in version 2.4:
maxset
,
maxfrozenset
，和
set
.
Repr.
maxlong
¶
Maximum number of characters in the representation for a long integer. Digits are dropped from the middle. The default is
40
.
Repr.
maxstring
¶
Limit on the number of characters in the representation of the string. Note that the “normal” representation of the string is used as the character source: if escape sequences are needed in the representation, these may be mangled when the representation is shortened. The default is
30
.
Repr.
maxother
¶
This limit is used to control the size of object types for which no specific formatting method is available on the
Repr
object. It is applied in a similar manner as
maxstring
。默认为
20
.
Repr.
repr1
(
obj
,
level
)
¶
Recursive implementation used by
repr()
. This uses the type of
obj
to determine which formatting method to call, passing it
obj
and
level
. The type-specific methods should call
repr1()
to perform recursive formatting, with
level - 1
for the value of
level
in the recursive call.
Repr.
repr_TYPE
(
obj
,
level
)
Formatting methods for specific types are implemented as methods with a name based on the type name. In the method name,
TYPE
被替换通过
string.join(string.split(type(obj).__name__, '_'))
. Dispatch to these methods is handled by
repr1()
. Type-specific methods which need to recursively format a value should call
self.repr1(subobj, level - 1)
.
The use of dynamic dispatching by
Repr.repr1()
allows subclasses of
Repr
to add support for additional built-in object types or to modify the handling of types already supported. This example shows how special support for file objects could be added:
import repr as reprlib import sys class MyRepr(reprlib.Repr): def repr_file(self, obj, level): if obj.name in ['<stdin>', '<stdout>', '<stderr>']: return obj.name else: return repr(obj) aRepr = MyRepr() print aRepr.repr(sys.stdin) # prints '<stdin>'