How can I read a python pickle database/file from C?

Question

I am working on integrating with several music players. At the moment my favorite is exaile.

In the new version they are migrating the database format from SQLite3 t

Answer 1

Like Cristian told, you can rather easily embed python code in your C code, see the example here.

Using cPickle is dead easy as well on python you could use something like:

import cPickle

f = open('dbfile', 'rb')
db = cPickle.load(f)
f.close()
# handle db integration
f = open('dbfile', 'wb')
cPickle.dump(db, f)
f.close()

Answer 2

http://www.picklingtools.com/

There is a library called the PicklingTools which I help maintain which might be useful: it allows you to form data structures in C++ that you can then pickle/unpickle ... it is C++, not C, but that shouldn't be a problem these days (assuming you are using the gcc/g++ suite).

The library is a plain C++ library (there are examples of C++ and Python within the distribution showing how to use the library over sockets and files from both C++ and Python), but in general, the basics of pickling to files is available.

The basic idea is that the PicklingTools library gives you "python-like" data structures from C++ so that you can then serialize and deserialize to/from Python/C++. All (?) the basic types: int, long int,string, None, complex, dictionarys, lists, ordered dictionaries and tuples are supported. There are few hooks to do custom classes, but that part is a bit immature: the rest of the library is pretty stable and has been active for 8 (?) years.

Simple example:

#include "chooseser.h"
int main()
{
  Val a_dict = Tab("{ 'a':1, 'b':[1,2.2,'three'], 'c':None }");
  cout << a_dict["b"][0];  // value of 1

  // Dump to a file
  DumpValToFile(a_dict, "example.p0", SERIALIZE_P0);

  // .. from Python, can load the dictionary with pickle.load(file('example.p0'))

  // Get the result back
  Val result;
  LoadValFromFile(result, "example.p0", SERIALIZE_P0);
  cout << result << endl;
}

There is further documentation (FAQ and User's Guide) on the web site.

Hope this is useful:

Gooday,

Richie

http://www.picklingtools.com/

Answer 3

You can embed a Python interpreter in a C program, but I think that the easiest solution is to write a Python script that converts "pickles" in another format, e.g. an SQLite database.