CODEWITHSUNDEEP
pythonctypes
Prog1020
Prog1020

Reputation: 4781

Cannot import ctypes on Linux

I have Linux Ubuntu x64 14.04 with Python 3.4 installed (default installation by Ubuntu). If I open CudaText text editor, it cannot import ctypes in console:

>>>> import ctypes
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python3.4/ctypes/__init__.py", line 7, in <module>
    from _ctypes import Union, Structure, Array
ImportError: /usr/lib/python3.4/lib-dynload/_ctypes.cpython-34m-x86_64-linux-gnu.so: undefined symbol: PyFloat_Type

Seems like Py3.4 installation is not full? Why it cannot load ctypes?

Upvotes: 1

Views: 1993

Answers (1)

Eryk Sun
Eryk Sun

Reputation: 34300

In Debian Linux distros such as Ubuntu, Python extension modules are built assuming Python's symbols are loaded globally, so they don't explicitly list the Python lib as a requirement in the ELF header. An embedding application that links dynamically needs to load the Python shared library to the global symbol table, e.g. dlopen("libpython3.4m.so", RTLD_GLOBAL | RTLD_NOW).

The author of the CudaText editor is using Python for Lazarus. I presume this uses dynlibs. As you can see in the source, it does not call dlopen with RTLD_GLOBAL. The default is RTLD_LOCAL (0).

Upvotes: 1

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