Conflict between uuid.uuid() from Python and std::rand() from C++ -


my soft written in c++ , called python scripts (through swig). when python function uuid.uuid1() called in scripts, seed used std::rand() of c++ seems lost. it's problem beacause have able relaunch soft same behaviour in c++ code (it's not matter uniqid's).

the problem simplified in following example :

c++ file testrand.h :

#ifndef __include__testrand_h__ #define __include__testrand_h__  void initialize(unsigned long int seed); unsigned long int get_number();  #endif

c++ file testrand.cpp :

#include "testrand.h"  #include <cstdlib>  void initialize(unsigned long int seed) {     std::srand(seed); }  unsigned long int get_number() {     return std::rand(); }

swig file testrand.i :

%module testrand %{     #include "testrand.h"  %} %include "testrand.h"

the compilation done following command :

swig -python -c++ testrand.i g++ -c -fpic testrand.cpp testrand_wrap.cxx -i/usr/include/python2.7/ g++ -shared testrand.o testrand_wrap.o -o _testrand.so

if launch following python testcase several times, can see first number same (as expected), second number, generated after call of uuid.uuid1() changes @ each run.

import testrand import uuid  testrand.initialize(10)  x1 = testrand.get_number() print x1  uuid.uuid1()  x2 = testrand.get_number() print x2

several runs :

> python testcase.py  1215069295 1691632206  > python testcase.py  1215069295 746144017  > python testcase.py  1215069295 377602282

have idea how can use python uuid without killing c++ seed ? in advance. (edit : configuration : linux opensuse 12.3, 64 bits, python 2.7.3 (but same problem 2.7.2), swig 2.0.9, gcc 4.7.2 (but same problem 4.5.1))

i found code of uuid here : http://pythoninside.com/en/source-code/2.7.5/uuid/uuid.py , copied , used code in example script (i.e. without import uuid). problem comes call _uuid_generate_time(_buffer) @ line 500. function defined alias of ctypes.cdll(ctypes.util.find_library('uuid')).uuid_generate_time @ lines 402-410. mention of bug found : https://savannah.cern.ch/bugs/?24456


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