[ python-Bugs-802310 ] tkFont may reuse font names

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Bugs item #802310, was opened at 2003-09-08 00:52
Message generated for change (Comment added) made by lpd
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Category: Tkinter
Group: None
Status: Open
Resolution: None
Priority: 3
Private: No
Submitted By: Fredrik Lundh (effbot)
Assigned to: Nobody/Anonymous (nobody)
Summary: tkFont may reuse font names

Initial Comment:
(sent to me instead of to the bug manager; note that 
the tkFont naming approach is also used for widgets and 
callbacks /F)

The class tkFont has a problem name it chooses if no 
name is
given. The choosen method 'name = "font" + str(id
(self))' isn't safe
because the name may exists longer than the Font 
object and so another
Font object may be created with a different font but the 
same
id() and so the same name. id() says

    Return the identity of an object.  This is guaranteed 
to be unique
    among simultaneously existing objects.
          ^^^^^^^^^^^^^^^^^^^^^^^

Note that this bug doesn't strike if you hold a reference 
to the Font
object and so the GC can't reclaim the space.

To reproduce run the attached program. It produces 
something like:

previously: ('Times', 15, 'bold')
now: ('Times', 18, 'bold')
iterations: 8
mapping: {'font136494612': ('Times', 
14, 'bold'), 'font136499772': ('Times', 
15, 'bold'), 'font136545468': ('Times', 
17, 'bold'), 'font136483156': ('Times', 
11, 'bold'), 'font136502700': ('Times', 
12, 'bold'), 'font136510460': ('Times', 
13, 'bold'), 'font136515228': ('Times', 
16, 'bold'), 'font136365348': ('Times', 10, 'bold')}
Traceback (most recent call last):
  File "tkfont_bug.py", line 20, in ?
    assert 0
AssertionError

Raimar


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Comment By: L. Peter Deutsch (lpd)
Date: 2007-06-02 22:16

Message:
Logged In: YES 
user_id=8861
Originator: NO

This bug has bitten me too, in a real program.

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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=802310&group_id=5470