Embedding Python into C/C++ applications

[John Dean]

Hi

Could somebody, please tell me where I can find information about embedding
Python into a C/C++ application. The example in the docs is rather simple. I
am looking for something a bit more complex and longer

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John
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Python V2.4.2 source code

[John Dean]

Hi

Does anybody know from where I can get a copy of the source for Python
V2.4.2. I downloaded what is reckoned to be the source code from
www.python.org, but is turns out to be the MacXOS version with the core
modules missing. The reason I am looking for the source code is so I can
make a debug build

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John
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Re: Python V2.4.2 source code

[John Dean]

Hi

That particular file doesn't include the implementation files for the core
modules. The platform specific directories only include two or three files.
Only the Mac directory contains any C code files

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John
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Re: Python V2.4.2 source code

[John Dean]

Hi

I downloaded what I thought was the source code from
http://www.python.org/2.4.2/python-2.4.2.tgz

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John
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Re: Python V2.4.2 source code

[John Dean]

Hi
Thank you very much. It seems the version tar that is embedded in WinRAR is
broken. It gets as far as the Mac directory and then bombs out. The version
of tar that is bundled with CygWin worked just fine

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John
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Embedded Python

[John Dean]

Hi
Is it possible to execute a whole script using the C API function
PyRun_String? At moment I load the script into a buffer. Then I get each
line of the script and pass it PyRun_String. This seems very inefficient. It
would be more efficient if I could pass the complete string buffer to
PyRun_String and execute the script as a whole

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John
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Problem with C-API

[John Dean]

Hi

I spent the whole of yesterday trying the get the following C code to
execute

PyRun_String("def title();", Py_file_input, dict, dict);
PyRun_String("\treturn 'Foo Bar'", Py_file_input, dict, dict);
PyRun_String("x = title()", Py_file_input, dict, dict);
PyObject * result = PyRun_String("print x", Py_file_input, dict, dict);
printf( "The result is %s\n", PyObject_AsString( result );

Each line throws an error.

Could somebody tell what is wrong with the above code.

Here below is the output from my test app

Starting Test ..

The file "testtitle" is open for reading

The variable codeStrings contains

Line 0  def title()
Line 1  return "Foo Bar"

The variable scriptText contains

def title()
return "Foo Bar"

The variable tempList contains

Line 0  testtitle
Line 1  title

Module Name is  testtitle

Function Name is  title

The variable functionCode contains

def title()
return "Foo Bar"

Python initialized successfully

Module object successfully created

Dict object successfully created

Failed to create a Result object.

The title of the this task is  

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John
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Re: Problem with C-API

[John Dean]

Hi Duncan

Your version of the app works apart from this part




else {
 PyObject *rString = PyObject_Str(result);
 if (rString==NULL) {
 Py_DECREF(result);
 PyErr_Print();
 return;
 }

 printf( "The result is %s\n", PyString_AsString(rString));
 Py_DECREF(rString);
 Py_DECREF(result);
}
}

The result of the printf state is: "The result is None"


result = PyRun_String("print x", Py_file_input, dict, dict);

The above line of code displays the value returned from the title()
function. My problem is I need to be able to cature the return value because
in the real application it will be displayed in a Process Log Widget. Also
the real scripts will be much longer.

I have not had a problem writing Python extensions, but when it comes to
embedded Python I just see how to get my code to work.

Any further help would be greatly appreciated

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John
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Re: Problem with C-API

[John Dean]

Hi

Duncan's example worked to a point. The line PyRun_String( "print x",
Py_file_input, dict, dict); print out the contents of x, but I don't want to
print x out. I want to be able to grab whateven the variable x contains so
that I can pass it on for further processing by the C++ application.

BTW this is only a test case. The real scripts are much bigger. I must say
the documentation is not of much help and there are no books or articles
covering embedding Python in any detail. What there is is very much out of
date.

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John
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