RE : RE : RE : [matplotlib-devel] crash on matplotlib.matlab import on win32

[Gregory L. <gre...@ff...>]

Another hackish debugging technique is to insert a lot of print
statements in matplotlib.matlab to find out where the crash is
occurring, ie, on which import line.

Good idea, this helped me to isolate the problem:
 it is in font_manager, in the createFontDict function...
Here is my output:

Import matplotlib
Matplotlib.use("PS")
Import matplotlib.font_manager
....lot of add_fname...
Add_fname
Done add_fname
Done add_decorated_fname
Assertion failed:ob_refcnt == 0 in cxx_extension.cxx, line 1031


With my "printified" createFontDict

def createFontDict(fontfiles, fontext='ttf'):
    """A function to create a dictionary of font file paths.  The
default is to create a dictionary for TrueType fonts.  An AFM font
dictionary can optionally be created.
"""
    print "in createFontDict"
    fontdict = {}
    #  Add fonts from list of known font files.
    seen = {}
    for fname in fontfiles:
        if seen.has_key(fname):  continue
        else: seen[fname] = 1
        if fontext == 'ttf':
            try:
                font = ft2font.FT2Font(str(fname))
            except RuntimeError:
                print >> sys.stderr, "Could not open font file", fname
                continue
            prop = ttfFontProperty(font)
        elif fontext == 'afm':
            try:
                #print 'parsing', fname
                font = afm.AFM(file(fname))
            except RuntimeError:
                print >> sys.stderr, "Could not open font file", fname
                continue
            print "calling afmFontProperty"    
            prop = afmFontProperty(font)
            print " done"
        print "add_fname"    
        add_filename(fontdict, prop, fname)
        print "done add_fname"

        #  !!!!  Default font algorithm needs improvement
        if   prop.name.lower() in ['bitstream vera serif', 'times']:
            prop.name = 'serif'
            add_filename(fontdict, prop, fname)
        elif prop.name.lower() in ['bitstream vera sans', 'helvetica']:
            prop.name = 'sans-serif'
            add_filename(fontdict, prop, fname)
        elif prop.name.lower() in ['zapf chancery', 'itc zapf
chancery']:
            prop.name = 'cursive'
            add_filename(fontdict, prop, fname)
        elif prop.name.lower() in ['western', 'itc avant garde gothic']:
            prop.name = 'fantasy'
            add_filename(fontdict, prop, fname)
        elif prop.name.lower() in ['bitstream vera sans mono',
'courier']:
            prop.name = 'monospace' 
            add_filename(fontdict, prop, fname)
        print "done add_decorated_fname"    
    print "now return fontdict"
    return fontdict


So it seems to crash at the end of the for loop, probably on destruction
of a 
Temporary object...strange, isn't it? Well, I hope it can help indentify
the problem, at least it isolated it somewhat...If you have any idea of
a test I can do for going further in the bug hunting (well, if it really
is a bug), I will be happy to do it :-)


Best regards,

Greg.