[Python-Dev] please consider changing --enable-unicode default to ucs4

M.-A. Lemburg mal at egenix.com
Mon Sep 28 10:36:07 CEST 2009

M.-A. Lemburg wrote:
> Also note that Python will complain loudly when you try to load
> a UCS2 extension in a UCS4 build and vice-versa. We've made sure
> that any extension using the Python Unicode C API has to be built
> for the same UCS version of Python. This is done by using different
> names for the C APIs at the C level.
>> These are not isolated incidents.  The following google searches
>> suggest that a number of people spend time trying to figure out why
>> Python extension modules fail on their linux systems:
>> http://www.google.com/search?q=PyUnicodeUCS4_FromUnicode+undefined+symbol
>> http://www.google.com/search?q=+PyUnicodeUCS2_FromUnicode+undefined+symbol
>> http://www.google.com/search?q=_PyUnicodeUCS2_AsDefaultEncodedString+undefined+symbol
> Perhaps we should add a FAQ entry for these linker errors
> (which are caused by the mentioned C API changes to prevent
> mixing UCS version) ?!

There already is one:


I wonder why it doesn't show up in the Google searches.

> Here's a quick way to determine you Python Unicode build type:
> python -c "import sys;print((sys.maxunicode<66000)and'UCS2'or'UCS4')"
> Perhaps we should include this info as well as an 32/64-bit indicator
> and the processor type in the Python startup line:
> # python
> Python 2.6 (r26:66714, Feb  3 2009, 20:49:49, UCS4, 64-bit, x86_64)
> [GCC 4.3.2 [gcc-4_3-branch revision 141291]] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> This would help users find the right binaries to install as
> extension.

Marc-Andre Lemburg

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