python: how to get the source from a code object? [duplicate]

Question

This question already has an answer here:

• Exploring and decompiling python bytecode [closed] 6 answers

let's suppose we have a python string(not a file,a string,no files)

TheString = "k=abs(x)+y"

ok? Now we compile the string into a piece of python bytecode

Binary = compile( TheString , "<string>" , "exec" )

now the problem: how can i get from Binary , supposing i don't know TheString , a string that represents the original string object?

shortly: what is the function that is opposite to compile() ?

Answer 1

Without the source code, you can only approximate the code. You can disassemble the compiled bytecode with the dis module, then reconstruct the source code as an approximation:

>>> import dis
>>> TheString = "k=abs(x)+y"
>>> Binary = compile( TheString , "<string>" , "exec" )
>>> dis.dis(Binary)
  1           0 LOAD_NAME                0 (abs)
              3 LOAD_NAME                1 (x)
              6 CALL_FUNCTION            1
              9 LOAD_NAME                2 (y)
             12 BINARY_ADD          
             13 STORE_NAME               3 (k)
             16 LOAD_CONST               0 (None)
             19 RETURN_VALUE        

From the disassembly we can see there was 1 line, where a function named abs() is being called with one argument named x. The result is added to another name y, and the result is stored in k.

Projects like uncompile6 (building on top of the work of many others) do just that; decompile the python bytecode and reconstruct Python code from that.