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author | Alexandre Vassalotti <alexandre@peadrop.com> | 2008-05-16 07:12:44 (GMT) |
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committer | Alexandre Vassalotti <alexandre@peadrop.com> | 2008-05-16 07:12:44 (GMT) |
commit | 1f2ba4b6dad80f97aeecb5be8f35f44ca792c983 (patch) | |
tree | dc2c356b160e3769dc758b55f72eba4bdf2ec652 /Doc/library/reprlib.rst | |
parent | cdc11337a221d45d40989bc256dd6cd0eb4b6371 (diff) | |
download | cpython-1f2ba4b6dad80f97aeecb5be8f35f44ca792c983.zip cpython-1f2ba4b6dad80f97aeecb5be8f35f44ca792c983.tar.gz cpython-1f2ba4b6dad80f97aeecb5be8f35f44ca792c983.tar.bz2 |
Rename the repr module to reprlib.
Merged revisions 63357 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
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r63357 | alexandre.vassalotti | 2008-05-16 02:58:49 -0400 (Fri, 16 May 2008) | 2 lines
Changed references to the reprlib module to use its new name.
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Diffstat (limited to 'Doc/library/reprlib.rst')
-rw-r--r-- | Doc/library/reprlib.rst | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/Doc/library/reprlib.rst b/Doc/library/reprlib.rst new file mode 100644 index 0000000..84fd6fb --- /dev/null +++ b/Doc/library/reprlib.rst @@ -0,0 +1,136 @@ + +:mod:`reprlib` --- Alternate :func:`repr` implementation +===================================================== + +.. module:: reprlib + :synopsis: Alternate repr() implementation with size limits. +.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org> + + +The :mod:`reprlib` 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: + + +.. class:: Repr() + + Class which provides formatting services useful in implementing functions + similar to the built-in :func:`repr`; size limits for different object types + are added to avoid the generation of representations which are excessively long. + + +.. data:: aRepr + + This is an instance of :class:`Repr` which is used to provide the :func:`repr` + function described below. Changing the attributes of this object will affect + the size limits used by :func:`repr` and the Python debugger. + + +.. function:: repr(obj) + + This is the :meth:`repr` method of ``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-objects: + +Repr Objects +------------ + +:class:`Repr` instances provide several members which can be used to provide +size limits for the representations of different object types, and methods +which format specific object types. + + +.. attribute:: Repr.maxlevel + + Depth limit on the creation of recursive representations. The default is ``6``. + + +.. attribute:: 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 :attr:`maxdict`, ``5`` for :attr:`maxarray`, and ``6`` for + the others. + + .. versionadded:: 2.4 + :attr:`maxset`, :attr:`maxfrozenset`, and :attr:`set`. + + +.. attribute:: Repr.maxlong + + Maximum number of characters in the representation for a long integer. Digits + are dropped from the middle. The default is ``40``. + + +.. attribute:: 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``. + + +.. attribute:: Repr.maxother + + This limit is used to control the size of object types for which no specific + formatting method is available on the :class:`Repr` object. It is applied in a + similar manner as :attr:`maxstring`. The default is ``20``. + + +.. method:: Repr.repr(obj) + + The equivalent to the built-in :func:`repr` that uses the formatting imposed by + the instance. + + +.. method:: Repr.repr1(obj, level) + + Recursive implementation used by :meth:`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 :meth:`repr1` to perform recursive formatting, + with ``level - 1`` for the value of *level* in the recursive call. + + +.. method:: Repr.repr_TYPE(obj, level) + :noindex: + + Formatting methods for specific types are implemented as methods with a name + based on the type name. In the method name, **TYPE** is replaced by + ``string.join(string.split(type(obj).__name__, '_'))``. Dispatch to these + methods is handled by :meth:`repr1`. Type-specific methods which need to + recursively format a value should call ``self.repr1(subobj, level - 1)``. + + +.. _subclassing-reprs: + +Subclassing Repr Objects +------------------------ + +The use of dynamic dispatching by :meth:`Repr.repr1` allows subclasses of +:class:`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 + import sys + + class MyRepr(repr.Repr): + def repr_file(self, obj, level): + if obj.name in ['<stdin>', '<stdout>', '<stderr>']: + return obj.name + else: + return `obj` + + aRepr = MyRepr() + print aRepr.repr(sys.stdin) # prints '<stdin>' + |