[Patches] [ python-Patches-1373762 ] Tweak pprint.PrettyPrinter.format for subclassing

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Patches item #1373762, was opened at 2005-12-05 14:21
Message generated for change (Comment added) made by fdrake
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Category: Library (Lib)
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Submitted By: Mark Hirota (markhirota)
Assigned to: Fred L. Drake, Jr. (fdrake)
Summary: Tweak pprint.PrettyPrinter.format for subclassing

Initial Comment:
The current format() method doesn't recursively apply 
an overridden format() method when the width of the 
object is too short.

This patch is designed to remove that limitation and 
allow a pprint.PrettyPrinter sublcass that could, for 
example, print all ints and longs in hex:

class MyPrettyPrinter(pprint.PrettyPrinter):
    def format(self, object, context, maxlevels, 
level):
        if isinstance(object, int):
            return hex(object), True, False
        else:
            return pprintmod.PrettyPrinter.format(
                self, object, context, maxlevels, 
level)


>>> mpp = MyPrettyPrinter()
>>> mpp.pprint(range(10))
[0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9]
>>> mpp.pprint(range(0x10000000,0x10000010))
[0x10000000,
 0x10000001,
 0x10000002,
 0x10000003,
 0x10000004,
 0x10000005,
 0x10000006,
 0x10000007,
 0x10000008,
 0x10000009,
 0x1000000a,
 0x1000000b,
 0x1000000c,
 0x1000000d,
 0x1000000e,
 0x1000000f]


The attached file contains "svn diff --diff-cmd diff -
x -b Lib/pprint.py".

----------------------------------------------------------------------

>Comment By: Fred L. Drake, Jr. (fdrake)
Date: 2005-12-05 15:48

Message:
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user_id=3066

Heh, reading the diff alone doesn't help me; there's no
helpful context.

While the example use case doesn't seem interesting, I
consider non-support of sub-class overriding the format()
method to be a bug.

I'll try and look at the patch more seriously soon, but I've
not managed to eek out many tuits lately, and this week is
as massively overbooked as any these days.

----------------------------------------------------------------------

Comment By: Raymond Hettinger (rhettinger)
Date: 2005-12-05 14:42

Message:
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user_id=80475

I don't find the use case to be even slightly motivating. 
Fred, what do you think of the patch?

----------------------------------------------------------------------

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