I have a python dictionary stored in a file which I need to access from a c++ program. What is the best way of doing this?
Thanks
3
-
"python dictionary stored in a file" - how did you store it? cPickle, json?eumiro– eumiro2010-10-19 07:48:58 +00:00Commented Oct 19, 2010 at 7:48
-
neither, it is written using a print statement to a filemikip– mikip2010-10-19 09:54:06 +00:00Commented Oct 19, 2010 at 9:54
-
Without any examples or sample code showing how you wrote it, we have nothing much to say. Please post your code.S.Lott– S.Lott2010-10-19 10:16:59 +00:00Commented Oct 19, 2010 at 10:16
Add a comment
|
3 Answers
How to do this depends on the python types you've serialised. Basically, python prints something like...
{1: 'one', 2: 'two'}
...so you need code to parse this. The simplest case is a flat map from one simple type to another, say int to int:
int key, value;
char c;
if (s >> c && c == '{')
while (s >> key)
{
if (s >> c && c == ':' && s >> value)
my_map[key] = value;
if (s >> c && c != ',')
break;
}
You can build on this, adding parsing error messages, supporting embedded containers, string types etc..
You may be able to find some existing implementation - I'm not sure. Anyway, this gives you a very rough idea of what they must do internally.
Comments
There are umpteen Python/C++ bindings (including the one in Boost) but I suggest KISS: not a Python/C++ binding but the principle "Keep It Simple, Stupid".
Use a Python program to access the dictionary. :-)
You can access the Python program(s) from C++ by running them, or you can do more fancy things such as communicating between Python and C++ via sockets or e.g. Windows "mailslots" or even some more full-fledged interprocess communication scheme.
Cheers & hth.
answered Oct 19, 2010 at 8:07
Cheers and hth. - Alf
146k15 gold badges218 silver badges342 bronze badges
Comments
I assume your Python dict is using simple data types and no objects (so strings/numbers/lists/nested dicts), since you want to use it in C++.
I would suggest using json library (http://docs.python.org/library/json.html) to deserialize it and then use a C++ equivalent to serialize it to a C++ object.
answered Oct 19, 2010 at 10:50
Torsten Engelbrecht
13.5k4 gold badges50 silver badges49 bronze badges