alpaca

Python Interoperability

• alpaca v0.2.0 comes with an experimental pybind11-based Python wrapper called pyalpaca.
• To build this wrapper, include the option -DALPACA_BUILD_PYTHON_LIB=on with cmake.
• Instead of providing a struct type, the user will provide a string specification of the fields.
• This is inspired by the standard Python struct module.

Example

Once the wrapper is built, simply add it to PYTHONPTAH and import pyalpaca.

import pyalpaca

# Create format string
format = '?cifs[i][[d]][3c]{c:i}{I}(cif)(s(dI))'

# Construct object
object = [
    False, 
    'a', 
    5, 
    3.14, 
    "Hello World!",
    [0, 1, 2, 3], 
    [[1.1, 2.2], [3.3, 4.4], [5.5, 6.6]],
    ['a', 'b', 'c'],
    {'a': 5, 'b': 19},
    {1, 1, 1, 2, 3, 4, 5, 5, 5, 5, 6},
    ('a', 45, 2.718),
    ("Hello", (39.456, 21))
]

# Serialize
bytes = pyalpaca.serialize(format, object)

# Print it
print("Bytes:")
hex_values = ["0x{:02x}".format(b) for b in bytes]
for i, h in enumerate(hex_values):
    if i > 0 and i % 8 == 0:
        print("\n  ", end="")
    elif i == 0 and i % 8 == 0:
        print("  ", end="")
    print(h, end=" ")
print()

# Deserialize
recovered = pyalpaca.deserialize(format, bytes)

# Print it
print("\nDeserialized:\n[ ")
for i in recovered:
    print("    " + str(i) + ",")
print("]")

pranav@ubuntu:~/dev/alpaca/build/python$ python3 test.py
Bytes:
  0x00 0x61 0x05 0xc3 0xf5 0x48 0x40 0x0c 
  0x48 0x65 0x6c 0x6c 0x6f 0x20 0x57 0x6f 
  0x72 0x6c 0x64 0x21 0x04 0x00 0x01 0x02 
  0x03 0x03 0x02 0x9a 0x99 0x99 0x99 0x99 
  0x99 0xf1 0x3f 0x9a 0x99 0x99 0x99 0x99 
  0x99 0x01 0x40 0x02 0x66 0x66 0x66 0x66 
  0x66 0x66 0x0a 0x40 0x9a 0x99 0x99 0x99 
  0x99 0x99 0x11 0x40 0x02 0x00 0x00 0x00 
  0x00 0x00 0x00 0x16 0x40 0x66 0x66 0x66 
  0x66 0x66 0x66 0x1a 0x40 0x61 0x62 0x63 
  0x02 0x61 0x05 0x62 0x13 0x06 0x01 0x02 
  0x03 0x04 0x05 0x06 0x61 0x2d 0xb6 0xf3 
  0x2d 0x40 0x05 0x48 0x65 0x6c 0x6c 0x6f 
  0xee 0x7c 0x3f 0x35 0x5e 0xba 0x43 0x40 
  0x15 

Deserialized:
[ 
    False,
    a,
    5,
    3.140000104904175,
    Hello World!,
    [0, 1, 2, 3],
    [[1.1, 2.2], [3.3, 4.4], [5.5, 6.6]],
    ['a', 'b', 'c'],
    {'a': 5, 'b': 19},
    {1, 2, 3, 4, 5, 6},
    ('a', 45, 2.7179999351501465),
    ('Hello', (39.456, 21)),
]