This patch removes the RegQueryInfoKey call and
replaces it with a call to EnumKeyEx. This greatly
speeds up this call. 

The script below times 

python 2.3              5531 89.7130000591
python 2.4 +patch   5531 0.0469999313354

start = time.time()
i = 0
try:
  while 1:
    _winreg.EnumKey(_winreg.HKEY_CLASSES_ROOT, i)
    i += 1
except WindowsError:
  pass
print i, time.time() - start

Logged In: YES 
user_id=74879

This looks good to me, but I think the buffer size is off by
one. I read the SDK to say tha they key can be 255
characters. That means you need to allocate 256 characters
to allow for the null terminator. Could you create a test
case for a max length registry key?

Logged In: YES 
user_id=11105

I'm curious: Why did you replace RegEnumKey with
RegEnumKeyEx? Are there any advantages of the latter?

Logged In: YES 
user_id=45280

mmangino: 

Yes you're correct it should be 256 in both cases. Doh! I'll
attach a new patch in a while. but It's easy to mmodify the
patch and up the linit to 256

theller:

The advantage of the latter is it returns the Length of the
string returned so we can pass it straight back to the
string creation funtion in python without a strlen.

also the SDK says this....

Note  This function is provided only for compatibility with
16-bit versions of Windows. Applications should use the
RegEnumKeyEx function.

Logged In: YES 
user_id=21627

Also, please follow the Python style guide for C code, PEP
7. In particular:
- use tabs for indentation, with a tab being worth 8 spaces
- omit spaces after opening and before closing parens
- put the opening brace of a code block on the same line as
the keyword

Logged In: YES 
user_id=1115903

I think it's a good idea to get 16-bit Windows functions out
of Python per Microsoft's recommendation, especially when
doing so can also help performance.  

It looks like this patch still needs some cleanup and a test
or two.  If nobody else wants to do it I can probably finish
it up.

Logged In: YES 
user_id=21627

garth42, can you please indicate whether you are willing to
work on the patch, and if so in what time frame?

Logged In: YES 
user_id=1188172

Attached a revised patch following coding style and adding
additional error handling.

winreg-enumkey.diff

Logged In: YES 
user_id=1188172

Cleaned up and committed in rev. 42475.