[Feat] encode by string (#8)

* bump ver

* add encode method

* fix sequences

* fix tuple encode

* nump ver

* use prerelease

* add encode example to readme

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "bt_decode"
-version = "0.1.0"
+version = "0.4.0-a0"
 edition = "2021"
 
 [lib]

README.md

@@ -288,3 +288,41 @@ neurons_lite: List[NeuronInfoLite] = bt_decode.decode(
     )
 )
 ```
+
+### encode by type string
+*Note: This feature is unstable, but working for multiple types.*
+
+You may also encode using a type-string formed from existing types by passing the metadata as pulled from a node (or formed manually).
+```python
+import bittensor, bt_decode, scalecodec
+# Get subtensor connection
+sub = bittensor.subtensor()
+# Create a param for the RPC call, using v15 metadata
+v15_int = scalecodec.U32()
+v15_int.value = 15
+# Make the RPC call to grab the metadata
+metadata_rpc_result = sub.substrate.rpc_request("state_call", [
+    "Metadata_metadata_at_version",
+    v15_int.encode().to_hex(),
+    sub.substrate.get_chain_finalised_head()
+])
+# Decode the metadata into a PortableRegistry type
+metadata_option_hex_str = metadata_rpc_result['result']
+metadata_option_bytes = bytes.fromhex(metadata_option_hex_str[2:])
+metadata_v15 = bt_decode.MetadataV15.decode_from_metadata_option(metadata_option_bytes)
+registry = bt_decode.PortableRegistry.from_metadata_v15( metadata_v15 )
+
+
+## Encode an integer as a compact u16
+compact_u16: list[int] = bt_decode.encode(
+    "Compact<u16>", # type-string,
+    2**16-1,
+    registry
+)
+# [254, 255, 3, 0]
+compact_u16_py_scale_codec = scalecodec.Compact()
+compact_u16_py_scale_codec.value = 2**16-1
+compact_u16_py_scale_codec.encode()
+
+assert list(compact_u16_py_scale_codec.data.data) == compact_u16
+```

bt_decode.pyi

@@ -349,3 +349,21 @@ def decode(
     type_string: str, portable_registry: PortableRegistry, encoded: bytes
 ) -> Any:
     pass
+
+def encode(
+    type_string: str, portable_registry: PortableRegistry, to_encode: Any
+) -> list[int]:
+    """
+    Encode a python object to bytes.
+
+    Returns a list of integers representing the encoded bytes.
+
+    Example:
+    >>> import bittensor as bt
+    >>> res = bt.decode.encode("u128", bt.decode.PortableRegistry.from_json(...), 1234567890)
+    >>> res
+    [210, 2, 150, 73, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
+    >>> bytes(res).hex()
+    'd2029649000000000000000000000000'
+    """
+    pass

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "bt-decode"
-version = "0.3.0a"
+version = "0.4.0-a0"
 description = "A wrapper around the scale-codec crate for fast scale-decoding of Bittensor data structures."
 readme = "README.md"
 license = {file = "LICENSE"}