[Python-Dev] Maintenance burden of str.swapcase

[Terry Reedy]

On 9/6/2011 12:58 PM, Tres Seaver wrote:
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> On 09/06/2011 12:59 PM, Stephen J. Turnbull wrote:
>> Joao S. O. Bueno writes:
>>
>>> Removing it would mean explicitly "batteries removal".
>>
>> That's what we usually do with a dead battery, no?<wink />
>
> Normally one "replaces" dead batteries. :)

Not if it is dead and leaking because the device has been unused for years.

https://www.google.com/codesearch#search/&q=lang:^python$%20swapcase%20case:yes&type=cs

returns a mere 300 hits. At least half are definitions of the function, 
or tests thereof, or inclusions in lists. Some actual uses:

1.http://pytof.googlecode.com/svn/trunk/pytof/utils.py
def ListCurrentDirFileFromExt(ext, path):
     """ list file matching extension from a list
     in the current directory
     emulate a `ls *.{(',').join(ext)` with ext in both upper and 
downcase}"""
     import glob
     extfiles = []
     for e in ext:
         extfiles.extend(glob.glob(join(path,'*' + e)))
         extfiles.extend(glob.glob(join(path,'*' + e.swapcase())))

If e is all upper or lower, using e.upper() and e.lower() will do same. 
If e is mixed, using .upper and .lower is required to fulfill the spec. 
On *nix, where matching of letters is case sensitive, both will fail 
with '.Jpg'. On Windows, where letter matching ignores case, the above 
code will list everything twice.

2.http://ydict.googlecode.com/svn/trunk/ydict
k is random word from database.

result.replace(k, "####").replace(k.upper(), 
"####").replace(k[0].swapcase()+k[1:].lower(),"####")

If k is lowercase, .lower() is redundant and 
k[0].swapcase()+k[1:].lower() == k.title(). If k is uppercase, previous 
.upper() is redundant. If k is mixed case, code may have problems.

3. http://migrid.googlecode.com/svn/trunk/mig/sftp-mount/migaccess.py

#    This is how we could add stub extended attribute handlers...
#    (We can't have ones which aptly delegate requests to the underlying fs
#    because Python lacks a standard xattr interface.)
#
#    def getxattr(self, path, name, size):
#        val = name.swapcase() + '@' + path
#        if size == 0:
#            # We are asked for size of the value.
#            return len(val)
#        return val

This is not actually used. Passing a name with all cases swapped from 
what they should be is a bit strange.

4.
                 elif char >= 'A' and  char <= 'Z':
                     element = element + char.swapcase()

uppercasechar.swapcase() == uppercasechar.lower()


My perusal of the first 70 of 300 hits suggests that .swapcase is more 
of an attractive nuisance or redundant rather than actually useful.

-- 
Terry Jan Reedy