bpo-40995: reprlib.Repr attributes can be overriden in __init__()

Doc/library/reprlib.rst

@@ -17,7 +17,9 @@ debugger and may be useful in other contexts as well.
 This module provides a class, an instance, and a function:
 
 
-.. class:: Repr()
+.. class:: Repr(self, *, maxlevel=6, maxtuple=6, maxlist=6, maxarray=5, \
+                 maxdict=4, maxset=6, maxfrozenset=6, maxdeque=6, maxstring=30, \
+                 maxlong=40, maxother=30)
 
    Class which provides formatting services useful in implementing functions
    similar to the built-in :func:`repr`; size limits for  different object types
@@ -71,72 +73,75 @@ string instead.
 Repr Objects
 ------------
 
-:class:`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.
+.. class:: Repr(self, *, maxlevel=6, maxtuple=6, maxlist=6, maxarray=5, \
+                 maxdict=4, maxset=6, maxfrozenset=6, maxdeque=6, maxstring=30, \
+                 maxlong=40, maxother=30)
 
+   :class:`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.
 
-.. attribute:: Repr.maxlevel
+   .. attribute:: maxlevel
 
-   Depth limit on the creation of recursive representations.  The default is ``6``.
+      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
+   .. attribute:: maxdict
+                  maxlist
+                  maxtuple
+                  maxset
+                  maxfrozenset
+                  maxdeque
+                  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.
+      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.
 
 
-.. attribute:: Repr.maxlong
+   .. attribute:: maxlong
 
-   Maximum number of characters in the representation for an integer.  Digits
-   are dropped from the middle.  The default is ``40``.
+      Maximum number of characters in the representation for an integer.  Digits
+      are dropped from the middle.  The default is ``40``.
 
 
-.. attribute:: Repr.maxstring
+   .. attribute:: 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``.
+      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
+   .. attribute:: 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``.
+      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)
+   .. method:: repr(obj)
 
-   The equivalent to the built-in :func:`repr` that uses the formatting imposed by
-   the instance.
+      The equivalent to the built-in :func:`repr` that uses the formatting imposed by
+      the instance.
 
 
-.. method:: Repr.repr1(obj, level)
+   .. method:: 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.
+      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:
+   .. method:: 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
-   ``'_'.join(type(obj).__name__.split())``. 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)``.
+      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
+      ``'_'.join(type(obj).__name__.split())``. 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:

Lib/reprlib.py

@@ -33,20 +33,23 @@ def wrapper(self):
 
     return decorating_function
 
+
 class Repr:
 
-    def __init__(self):
-        self.maxlevel = 6
-        self.maxtuple = 6
-        self.maxlist = 6
-        self.maxarray = 5
-        self.maxdict = 4
-        self.maxset = 6
-        self.maxfrozenset = 6
-        self.maxdeque = 6
-        self.maxstring = 30
-        self.maxlong = 40
-        self.maxother = 30
+    def __init__(self, *, maxlevel=6, maxtuple=6, maxlist=6, maxarray=5,
+                 maxdict=4, maxset=6, maxfrozenset=6, maxdeque=6, maxstring=30,
+                 maxlong=40, maxother=30):
+        self.maxlevel = maxlevel
+        self.maxtuple = maxtuple
+        self.maxlist = maxlist
+        self.maxarray = maxarray
+        self.maxdict = maxdict
+        self.maxset = maxset
+        self.maxfrozenset = maxfrozenset
+        self.maxdeque = maxdeque
+        self.maxstring = maxstring
+        self.maxlong = maxlong
+        self.maxother = maxother
 
     def repr(self, x):
         return self.repr1(x, self.maxlevel)

Lib/test/test_reprlib.py

@@ -216,6 +216,13 @@ def test_unsortable(self):
         r(y)
         r(z)
 
+    def test___init__(self):
+        a = "a"*40
+        r = Repr()
+        self.assertEqual(r.repr(a), "'aaaaaaaaaaaa...aaaaaaaaaaaaa'")
+        r = Repr(maxstring=10)
+        self.assertEqual(r.repr(a), "'aa...aaa'")
+
 def write_file(path, text):
     with open(path, 'w', encoding='ASCII') as fp:
         fp.write(text)

Misc/NEWS.d/next/Library/2020-06-17-01-07-36.bpo-40995.2IvRr2.rst

@@ -0,0 +1,2 @@
+:class:`reprlib.Repr` attributes can now be set when creating an instance.
+Patch contributed by Rémi Lapeyre.