How do you properly determine the current script directory in Python?

Question

I would like to see what is the best way to determine the current script directory in Python.

I discovered that, due to the many ways of calling Python code, it is ha

Answer 1

First.. a couple missing use-cases here if we're talking about ways to inject anonymous code..

code.compile_command()
code.interact()
imp.load_compiled()
imp.load_dynamic()
imp.load_module()
__builtin__.compile()
loading C compiled shared objects? example: _socket?)

But, the real question is, what is your goal - are you trying to enforce some sort of security? Or are you just interested in whats being loaded.

If you're interested in security, the filename that is being imported via exec/execfile is inconsequential - you should use rexec, which offers the following:

This module contains the RExec class, which supports r_eval(), r_execfile(), r_exec(), and r_import() methods, which are restricted versions of the standard Python functions eval(), execfile() and the exec and import statements. Code executed in this restricted environment will only have access to modules and functions that are deemed safe; you can subclass RExec add or remove capabilities as desired.

However, if this is more of an academic pursuit.. here are a couple goofy approaches that you might be able to dig a little deeper into..

Example scripts:

./deep.py

print ' >> level 1'
execfile('deeper.py')
print ' << level 1'

./deeper.py

print '\t >> level 2'
exec("import sys; sys.path.append('/tmp'); import deepest")
print '\t << level 2'

/tmp/deepest.py

print '\t\t >> level 3'
print '\t\t\t I can see the earths core.'
print '\t\t << level 3'

./codespy.py

import sys, os

def overseer(frame, event, arg):
    print "loaded(%s)" % os.path.abspath(frame.f_code.co_filename)

sys.settrace(overseer)
execfile("deep.py")
sys.exit(0)

Output

loaded(/Users/synthesizerpatel/deep.py)
>> level 1
loaded(/Users/synthesizerpatel/deeper.py)
    >> level 2
loaded(/Users/synthesizerpatel/)
loaded(/tmp/deepest.py)
        >> level 3
            I can see the earths core.
        << level 3
    << level 2
<< level 1

Of course, this is a resource-intensive way to do it, you'd be tracing all your code.. Not very efficient. But, I think it's a novel approach since it continues to work even as you get deeper into the nest. You can't override 'eval'. Although you can override execfile().

Note, this approach only coveres exec/execfile, not 'import'. For higher level 'module' load hooking you might be able to use use sys.path_hooks (Write-up courtesy of PyMOTW).

Thats all I have off the top of my head.