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Getting 'prints' from an embedded Python?

Started by Ezbez Oct 20, 2006 at 6:00 AM 4 replies 2.5k views

Original Post

Oct 20, 2006 at 6:00 AM

I've embedded Python into my game. I'd like to be able to print text out from Python, but doing that doesn't seem to actually output anything. Since all the tutorials that start off with "Hello, world" scripts have a console opened and the Python output went to that console, I was thinking that because I didn't have a console, it wasn't actually going anywhere. In that case, how can I 'grab' the Python prints in my C++ program? Or, how can I redirect them to a file? Thanks in advanced.

jochen

Oct 20, 2006 at 6:14 AM

If you export a method that takes a string as a parameter, you can install that as pythons std::out sink. It's pretty simple if u e.g. use boost::python.

Unfortunatly I don't have src code available right now. If nbdy else does before me, I will post some code, when I get home from work. :-)

Ezbez

Oct 20, 2006 at 6:23 AM

Yes, I am using Boost.Python. I'd love to see that source code when you're back, since I can't find any information about this in the Boost.Python documentation.

Emmanuel77

Oct 20, 2006 at 7:03 AM

You just have to set stdout to a class with a write method, that do whatever you want.

Here is a tutorial that explain how to do this :

http://www.ragestorm.net/tutorial?id=21

Hope it helps,

Emmanuel

jochen

Oct 20, 2006 at 12:16 PM

ah I c sbdy already supplied a tutorial....

However I just put together some code from a former project right now.
I have to appologize, I didn't test it before posting, cause I'm in a little hurry, but since I promised to to so, here is some code:

void TraceCB( const std::string& i_String ){	LOG_STRING( i_String );}/////////////////////////////////////////////////////////////////////void ErrorCB( const std::string& i_String ){	LOG_STRING( i_String );}/////////////////////////////////////////////////////////////////////BOOST_PYTHON_MODULE( LogModule ){	using namespace boost::python;	def( "TraceCB", TraceCB );	def( "ErrorCB", ErrorCB );}/////////////////////////////////////////////////////////////////////void InitializeLogModule( void ){	initLogModule()}/////////////////////////////////////////////////////////////////////bool RunTestScript( const std::string& i_Script ){	using namespace boost::python;	try	{		object MainModule( handle<>( borrowed( PyImport_AddModule("__main__") ) ) );		object MainNamespace = MainModule.attr( "__dict__" );		handle<> Result( allow_null( PyRun_String(	FixEndLines( i_Script ).c_str(),							Py_file_input,							MainNamespace.ptr(),							MainNamespace.ptr() )));		if ( !Result )		{			EOKANE_ERROR( "Python script execution failed." );			PyErr_Print();			return false;		}		return true;			}	catch( ... )	{		EOKANE_ERROR( "Critical error while executing python script." );		PyErr_Print();	}	return false;}int main( int argc, char** argv ){	Py_InitializeEx( 0 );	if ( Py_IsInitialized() )	{		InitializeLogModule();		std::string Script( "import sys"							"import LogModule"							""							"class StdOutRedirector:"							"	def write( i_Self, i_String ):"							"	LogModule.TraceCB( i_String )"							""							"class StdErrorRedirector:"							"	def write( i_Self, i_String ):"							"		LogModule.ErrorCB( i_String )"							""							"sys.stdout = StdOutRedirector();"							"sys.stderr = StdErrorRedirector();"							""							"print \"Hello World\"" );				RunTestScript( Script );		Py_Finalize();	}	}

if you can't get it going, just drop me a line and I'll try to put together a little project u can step through with the debugger... that's what I like best for myself.

Cheers Jochen

Ezbez

Oct 21, 2006 at 2:58 PM

I got it working now, many thanks!

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