Re: 'Import sys' succeeds in C++ embedded code, but module is not fully visible
Ben Sizer wrote: Yes, this seems to fix it, thanks. But why? Can some Python guru explain why these two dictionaries must be the same? (Or what steps we must take if we want them to be separate?) What's happening is that the import statement is binding the name 'sys' in the locals, not the globals. You don't notice this in the top-level code, since both are in scope there. But inside the function you can only see the top-level globals plus the function's own locals. I had hoped to be able to clear out the locals dictionary while leaving useful functions intact in the globals dictionary, but it would appear that is not practical. You can probably do that by using global statements in the top-level code for the things you want to preserve, e.g. global sys import sys my_local_var = 42 global f def f(): print This function is in globals and can see sys.path print sys.path def g(): print This function is in locals and can't see sys.path Now clearing the locals will remove g and my_local_var while leaving the rest in globals. The only restriction is that anything you want to refer to from a function will have to be in the globals. This includes other functions -- i.e. f() won't be able to call g() in the example above. -- Greg -- http://mail.python.org/mailman/listinfo/python-list
Re: 'Import sys' succeeds in C++ embedded code, but module is not fully visible
In article b11e6e8a-98a6-43d1-b311-652fedbe7...@h5g2000yqh.googlegroups.com, Ben Sizer kylo...@gmail.com wrote: I have the following C++ code and am attempting to embed Python 2.5, but although the import sys statement works, attempting to reference sys.path from inside a function after that point fails. It's as if it's not treating it as a normal module but as any other global variable which I'd have to explicitly qualify. After skimming the thread and seeing a lack of answer, I suggest you try capi-...@python.org -- Aahz (a...@pythoncraft.com) * http://www.pythoncraft.com/ Weinberg's Second Law: If builders built buildings the way programmers wrote programs, then the first woodpecker that came along would destroy civilization. -- http://mail.python.org/mailman/listinfo/python-list
Re: 'Import sys' succeeds in C++ embedded code, but module is not fully visible
On Jan 14, 4:37 pm, Ivan Illarionov ivan.illario...@gmail.com wrote: On Jan 14, 1:49 pm, Ben Sizer kylo...@gmail.com wrote: No, I don't want to do anything with sys.path apart from see it. I just wanted my original question answered, not a guess at my intent and a solution for something I'm not doing. ;) Thanks though! Again - why can I not reference sys from within the function? Ah, sorry for wrong guess. I would try to use ourNamespace_ dict for both globals and locals in PyRun_String call. Yes, this seems to fix it, thanks. But why? Can some Python guru explain why these two dictionaries must be the same? (Or what steps we must take if we want them to be separate?) The documentation is not very clear. I had hoped to be able to clear out the locals dictionary while leaving useful functions intact in the globals dictionary, but it would appear that is not practical. (On a separate note, while trying to debug this it seemed that Python will look for debug versions of a library when you embed it in debug mode, and will fail to find a module if you only have the release versions there. The error message you get isn't too helpful about this however, and I only worked it out by looking at the very long list of filesystem calls Python made to try and find it. Anybody wishing to speed up import times might want to ensure they don't have a long Python path and as few eggs in site-packages as possible.) -- Ben Sizer -- http://mail.python.org/mailman/listinfo/python-list
Re: 'Import sys' succeeds in C++ embedded code, but module is not fully visible
On Jan 14, 1:55 am, Ivan Illarionov ivan.illario...@gmail.com wrote: Ben Sizer kylo...@gmail.com wrote: What am I doing wrong? What are you trying to achieve? If you want to modify sys.path I suggest using Python/C API directly: No, I don't want to do anything with sys.path apart from see it. I just wanted my original question answered, not a guess at my intent and a solution for something I'm not doing. ;) Thanks though! Again - why can I not reference sys from within the function? -- Ben Sizer -- http://mail.python.org/mailman/listinfo/python-list
Re: 'Import sys' succeeds in C++ embedded code, but module is not fully visible
On Jan 14, 1:49 pm, Ben Sizer kylo...@gmail.com wrote: No, I don't want to do anything with sys.path apart from see it. I just wanted my original question answered, not a guess at my intent and a solution for something I'm not doing. ;) Thanks though! Again - why can I not reference sys from within the function? Ah, sorry for wrong guess. I would try to use ourNamespace_ dict for both globals and locals in PyRun_String call. -- Ivan -- http://mail.python.org/mailman/listinfo/python-list
Re: 'Import sys' succeeds in C++ embedded code, but module is not fully visible
On Jan 14, 4:37 pm, Ivan Illarionov ivan.illario...@gmail.com wrote: I would try to use ourNamespace_ dict for both globals and locals in PyRun_String call. I will try it when I get home. However I would like to be able to treat them as separate dictionaries, as I want to be able to import some symbols and modules at a global level, but be able to clear out objects introduced at the local level on a periodic basis, so that I can have some degree of isolation between distinct 'scripts'. The docs aren't terribly clear about what the globals and locals parameters to PyRun_String actually do, though. I also wonder if this is something specific to the sys module, since it's already been shown that there are some specific C API functions for it. I will try with other modules and see if they exhibit the same symptoms. And I'm still wondering about the sys.path[0] question. :) -- Ben Sizer -- http://mail.python.org/mailman/listinfo/python-list
Re: 'Import sys' succeeds in C++ embedded code, but module is not fully visible
On Jan 14, 8:00 pm, Ben Sizer kylo...@gmail.com wrote: I will try it when I get home. However I would like to be able to treat them as separate dictionaries, as I want to be able to import some symbols and modules at a global level, but be able to clear out objects introduced at the local level on a periodic basis, so that I can have some degree of isolation between distinct 'scripts'. The docs aren't terribly clear about what the globals and locals parameters to PyRun_String actually do, though. I also wonder if this is something specific to the sys module, since it's already been shown that there are some specific C API functions for it. I will try with other modules and see if they exhibit the same symptoms. After quick testing it looks like '__builtins__' must be in locals dictionary for your embed Python code to work, it may be a separate dictionary from globals though. From what I know 'sys' module is related to builtins. My knowledge of Python internals is not so deep to explain the details of this relationship and answer your question about sys.path[0] though. -- Ivan -- http://mail.python.org/mailman/listinfo/python-list
Re: 'Import sys' succeeds in C++ embedded code, but module is not fully visible
On Jan 14, 8:17 pm, Ivan Illarionov ivan.illario...@gmail.com wrote: On Jan 14, 8:00 pm, Ben Sizer kylo...@gmail.com wrote: I will try it when I get home. However I would like to be able to treat them as separate dictionaries, as I want to be able to import some symbols and modules at a global level, but be able to clear out objects introduced at the local level on a periodic basis, so that I can have some degree of isolation between distinct 'scripts'. The docs aren't terribly clear about what the globals and locals parameters to PyRun_String actually do, though. I also wonder if this is something specific to the sys module, since it's already been shown that there are some specific C API functions for it. I will try with other modules and see if they exhibit the same symptoms. After quick testing it looks like '__builtins__' must be in locals dictionary for your embed Python code to work, it may be a separate dictionary from globals though. From what I know 'sys' module is related to builtins. My knowledge of Python internals is not so deep to explain the details of this relationship and answer your question about sys.path[0] though. Sorry, I probably was terribly wrong in my last post, it doesn't work this way with separate dictionaries. I never had to use separate dictionaries. Maybe someone with better knowledge of Python internals may help? -- Ivan -- http://mail.python.org/mailman/listinfo/python-list
'Import sys' succeeds in C++ embedded code, but module is not fully visible
I have the following C++ code and am attempting to embed Python 2.5,
but although the import sys statement works, attempting to reference
sys.path from inside a function after that point fails. It's as if
it's not treating it as a normal module but as any other global
variable which I'd have to explicitly qualify.
Py_InitializeEx(0); // the zero skips registration of signal
handlers.
PyObject* ourNamespace_ = PyDict_New();
PyDict_SetItemString(ourNamespace_, __builtins__,
PyEval_GetBuiltins());
PyObject* locals = PyDict_New();
const char* scriptStr =
print '1'\n
import sys\n
print sys.path\n
def debug_path_info():\n
print 'These are the directories Python looks into for
modules and source files:'\n
print '2'\n
for folder in sys.path:\n
print folder\n
print '--'\n
print 'This would be your present working folder/
directory:'\n
print '3'\n
print sys.path[0]\n
debug_path_info()\n;
PyObject* scriptResult = PyRun_String(
scriptStr, // Python code to execute
Py_file_input,
ourNamespace_, // globals dictionary
locals);// locals dictionary
if (!scriptResult)
{
std::cerr Python error: Unhandled Python exception
from
script. std::endl;
PyErr_Print();
}
else
{
Py_DECREF(scriptResult); // don't need result any more
}
Py_DECREF(locals);
Py_DECREF(ourNamespace_);
Py_Finalize();
And the output is like this:
1
['E:\\code\\Python25\\lib\\site-packages\\turbokid-1.0.4-py2.5.egg',
'E:\\code\\
Python25\\lib\\site-packages\\turbocheetah-1.0-py2.5.egg', 'E:\\code\
\Python25\\
lib\\site-packages\\simplejson-1.8.1-py2.5-win32.egg', 'E:\\code\
\Python25\\lib\
\site-packages\\ruledispatch-0.5a0.dev_r2306-py2.5-win32.egg', 'E:\
\code\\Python
25\\lib\\site-packages\\pastescript-1.6.2-py2.5.egg', 'E:\\code\
\Python25\\lib\\
site-packages\\formencode-1.0.1-py2.5.egg', 'E:\\code\\Python25\\lib\
\site-packa
ges\\decoratortools-1.7-py2.5.egg', 'E:\\code\\Python25\\lib\\site-
packages\\con
figobj-4.5.2-py2.5.egg', 'E:\\code\\Python25\\lib\\site-packages\
\cherrypy-2.3.0
-py2.5.egg', 'E:\\code\\Python25\\lib\\site-packages\\kid-0.9.6-
py2.5.egg', 'E:\
\code\\Python25\\lib\\site-packages\\cheetah-2.0.1-py2.5-win32.egg',
'E:\\code\\
Python25\\lib\\site-packages\\pyprotocols-1.0a0-py2.5-win32.egg', 'E:\
\code\\Pyt
hon25\\lib\\site-packages\\pastedeploy-1.3.1-py2.5.egg', 'E:\\code\
\Python25\\li
b\\site-packages\\paste-1.6-py2.5.egg', 'E:\\code\\Python25\\lib\\site-
packages\
\sqlobject-0.10.0-py2.5.egg', 'E:\\code\\Python25\\lib\\site-packages\
\tgfastdat
a-0.9a7-py2.5.egg', 'E:\\code\\Python25\\lib\\site-packages\
\webhelpers-0.6-py2.
5.egg', 'E:\\code\\Python25\\lib\\site-packages\\shove-0.1.3-
py2.5.egg', 'E:\\co
de\\Python25\\lib\\site-packages\\boto-1.3a-py2.5.egg', 'E:\\code\
\Python25\\lib
\\site-packages\\sqlalchemy-0.5.0beta3-py2.5.egg', 'E:\\code\\Python25\
\lib\\sit
e-packages\\turbojson-1.1.4-py2.5.egg', 'E:\\code\\Python25\\lib\\site-
packages\
\setuptools-0.6c9-py2.5.egg', 'E:\\code\\Python25\\lib\\site-packages\
\turbogear
s-1.0.8-py2.5.egg', 'C:\\WINDOWS\\system32\\python25_d.zip', 'E:\\code\
\Python25
\\Lib', 'E:\\code\\Python25\\DLLs', 'E:\\code\\Python25\\Lib\\lib-tk',
'e:\\Visu
al Studio 2008\\Projects\\StacklessEmbed\\StacklessEmbed', 'e:\\Visual
Studio 20
08\\Projects\\StacklessEmbed\\Debug', 'E:\\code\\Python25', 'E:\\code\
\Python25\
\lib\\site-packages', 'E:\\code\\Python25\\lib\\site-packages\\PIL',
'E:\\code\\
Python25\\lib\\site-packages\\wx-2.8-msw-unicode']
These are the directories Python looks into for modules and source
files:
2
Python error: Unhandled Python exception from script.
Traceback (most recent call last):
File string, line 13, in module
File string, line 7, in debug_path_info
NameError: global name 'sys' is not defined
[12532 refs]
(Incidentally, the Stackless references are because I was originally
trying to embed Stackless, but I reverted to vanilla 2.5 to see if it
was a Stackless specific issue, which it appears not.)
Another interesting thing is that sys.path[0] doesn't appear to be the
current working directory, despite several sources online suggesting
it should be.
What am I doing wrong?
--
Ben Sizer
--
http://mail.python.org/mailman/listinfo/python-list
Re: 'Import sys' succeeds in C++ embedded code, but module is not fully visible
Ben Sizer kylo...@gmail.com wrote: What am I doing wrong? What are you trying to achieve? If you want to modify sys.path I suggest using Python/C API directly: (boilerplate removed) PyImport_ImportModule(sys) PyObject_GetAttrString(sysmod_pointer, path) PyList_Insert(pathobj_pointer, 0, path_python_str) -- Ivan -- http://mail.python.org/mailman/listinfo/python-list
Re: 'Import sys' succeeds in C++ embedded code, but module is not fully visible
Ivan Illarionov schrieb:
Ben Sizer kylo...@gmail.com wrote:
What am I doing wrong?
What are you trying to achieve?
If you want to modify sys.path I suggest using Python/C API directly:
(boilerplate removed)
PyImport_ImportModule(sys)
PyObject_GetAttrString(sysmod_pointer, path)
PyList_Insert(pathobj_pointer, 0, path_python_str)
The sys module has its own set of special functions like
PySys_GetObject. The following (untested) code should take care of error
checking and ref counting.
#include Python.h
PyObject*
addtosyspath(const char* addpath) {
PyObject *syspath=NULL, *path=NULL;
int result;
if ((syspath = PySys_GetObject(path)) == NULL)
return NULL;
if ((path = PyString_FromString(addpath) == NULL) {
Py_DECREF(syspath);
return NULL;
}
result = PyList_Insert(syspath, 0, path);
Py_DECREF(syspath);
Py_DECREF(path);
if (result != 0)
return NULL;
Py_RETURN_NONE;
}
Christian
--
http://mail.python.org/mailman/listinfo/python-list
