Add basic configurable Method class with attr lookup

- Demonstrates limited feature set using the Version module

Author: dylanjw

tests/core/base-module/test_base_module.py

@@ -0,0 +1,21 @@
+import pytest
+
+from web3.module import Module
+
+
+class DummyWeb3:
+    def __init__(self):
+        Module.attach(self, 'module')
+
+
+@pytest.fixture(scope='module')
+def dw3():
+    w3 = DummyWeb3()
+    return w3
+
+
+def test_module_lookup_method(dw3):
+    with pytest.raises(AttributeError):
+        assert dw3.module.blahblahblah
+    dw3.module.lookup_method_fn = lambda *_: True
+    assert dw3.module.blahblahblah is True

tests/core/version-module/test_version_module.py

@@ -0,0 +1,52 @@
+import pytest
+
+from web3 import Web3, EthereumTesterProvider
+from web3.providers.eth_tester.main import AsyncEthereumTesterProvider
+from web3.version import BlockingVersion, AsyncVersion, Version
+
+
+@pytest.fixture
+def blocking_w3():
+    return Web3(
+        EthereumTesterProvider(),
+        modules={
+            'blocking_version': BlockingVersion,
+            'legacy_version': Version
+        })
+
+
+@pytest.fixture
+def async_w3():
+    return Web3(
+        AsyncEthereumTesterProvider(),
+        middlewares=[],
+        modules={
+            'async_version': AsyncVersion,
+        })
+
+
+def test_blocking_version(blocking_w3):
+    assert blocking_w3.blocking_version.api == blocking_w3.legacy_version.api
+    assert blocking_w3.blocking_version.node == blocking_w3.legacy_version.node
+    assert blocking_w3.blocking_version.network == blocking_w3.legacy_version.network
+    assert blocking_w3.blocking_version.ethereum == blocking_w3.legacy_version.ethereum
+
+
+@pytest.mark.asyncio
+async def test_async_blocking_version(async_w3, blocking_w3):
+    #  This seems a little awkward.  How do we know if something is an awaitable
+    #  or a static method?
+    assert async_w3.async_version.api == blocking_w3.legacy_version.api
+
+    assert await async_w3.async_version.node == blocking_w3.legacy_version.node
+    with pytest.raises(
+        ValueError,
+        message="RPC Endpoint has not been implemented: net_version"
+    ):
+        #  net_version is provided through a middleware
+        assert await async_w3.async_version.network == blocking_w3.legacy_version.network
+    with pytest.raises(
+        ValueError,
+        message="RPC Endpoint has not been implemented: eth_protocolVersion"
+    ):
+        assert await async_w3.async_version.ethereum == blocking_w3.legacy_version.ethereum

web3/exceptions.py

@@ -114,3 +114,7 @@ class TimeExhausted(Exception):
     Raised when a method has not retrieved the desired result within a specified timeout.
     """
     pass
+
+
+class UndefinedMethodError(Exception):
+    pass

web3/method.py

@@ -0,0 +1,144 @@
+from eth_utils import (
+    to_tuple,
+)
+from eth_utils.toolz import (
+    identity,
+    pipe,
+)
+
+from web3.exceptions import (
+    UndefinedMethodError,
+)
+
+TEST_METHOD_CONFIG = {
+    'name': "signInBlood",
+    'mungers': [],
+    'json_rpc_method': "eth_signTransactionInBlood",
+}
+
+
+def lookup_method(module, module_config, method_class, attr_name):
+    try:
+        method = module_config[attr_name]
+    except KeyError:
+        raise UndefinedMethodError("No method named {0}".format(attr_name))
+    return method_class(module.web3, method)
+
+
+class DummyRequestManager:
+    def request_blocking(method, params):
+        return (method, params)
+
+
+class DummyWeb3:
+    manager = DummyRequestManager
+
+
+def test_sync_method_config_loading():
+    signInBlood = BlockingMethod(DummyWeb3(), TEST_METHOD_CONFIG)
+    signInBlood.input_munger = lambda *_: {}
+    assert signInBlood.method_selector
+    assert ('eth_signTransactionInBlood', {}) == signInBlood()
+
+
+class BaseMethod:
+    """BaseMethod for web3 module methods
+
+    Calls to the Method go through these steps:
+
+    1. input munging ;) - includes normalization, parameter checking, formatters.
+    Any processing on the input parameters that need to happen before json_rpc
+    method string selection occurs.
+
+    2. method selection - function that selects the correct rpc_method. accepts a
+    function or an string.
+
+    3. constructing formatter middlewares - takes the rpc_method and looks up the
+    corresponding input/output formatters. these are the middlewares migrated here.
+
+    4. making the request through the middleware (pipeline)? wrapped request
+    function.
+    """
+    def __init__(self, web3, method_config):
+        self.__name__ = method_config.get('name', 'anonymous')
+        self.__doc__ = method_config.get('doc', '')
+        self.is_property = method_config.get('is_property', False)
+        self.web3 = web3
+        self.input_munger = self._construct_input_pipe(
+            method_config.get('mungers')) or identity
+        self.method_selector = self._method_selector(
+            method_config.get('json_rpc_method'))
+        #  TODO: Write formatter lookup.
+        self.lookup_formatter = None
+
+    def _construct_input_pipe(self, formatters):
+        formatters = formatters or [identity]
+
+    def _method_selector(self, selector):
+        """Method selector can just be the method string.
+        """
+        if isinstance(selector, (str,)):
+            return lambda _: selector
+        else:
+            return selector
+
+    def get_formatters(self, method_string):
+        """Lookup the request formatters for the rpc_method"""
+        if not self.lookup_formatter:
+            return ([identity], [identity],)
+        else:
+            raise NotImplementedError()
+
+    def prep_for_call(self, *args, **kwargs):
+        # takes in input params, steps 1-3
+        params, method, (req_formatters, ret_formatters) = pipe_appends(
+            [self.input_munger, self.method_selector, self.get_formatters],
+            (args, kwargs,))
+        return pipe((method, params,), *req_formatters), ret_formatters
+
+    def __call__(self):
+        raise NotImplementedError()
+
+
+@to_tuple
+def pipe_appends(fns, val):
+    """pipes val through a list of fns while appending the result to the
+    tuple output
+
+    e.g.:
+
+        >>> pipe_appends([lambda x: x**2, lambda x: x*10], 5)
+        (25, 250)
+
+    """
+    for fn in fns:
+        val = fn(val)
+        yield val
+
+
+class BlockingMethod(BaseMethod):
+    def __call__(self, *args, **kwargs):
+        (method, params), output_formatters = self.prep_for_call(*args, **kwargs)
+        return pipe(
+            self.web3.manager.request_blocking(method, params),
+            *output_formatters)
+
+    def __get__(self, obj, objType):
+        # allow methods to be configured for property access
+        if self.is_property is True:
+            return self.__call__()
+        else:
+            return self
+
+
+class AsyncMethod(BaseMethod):
+    async def __call__(self, *args, **kwargs):
+        (method, params), output_formatters = self.prep_for_call(*args, **kwargs)
+        raw_result = await self.web3.manager.request_async(method, params)
+        return pipe(raw_result, *output_formatters)
+
+    async def __get__(self, obj, objType):
+        if self.is_property is True:
+            return await self.__call__()
+        else:
+            return self

web3/module.py

@@ -1,8 +1,38 @@
+from web3.exceptions import (
+    UndefinedMethodError,
+)
+from web3.method import (
+    lookup_method,
+)
+
+
 class Module:
     web3 = None
+    method_class = None
+    module_config = None
+    lookup_method_fn = lookup_method
 
     def __init__(self, web3):
         self.web3 = web3
+        if self.module_config is None:
+            self.module_config = dict()
+
+    def __getattr__(self, attr):
+        #  Method lookup magic
+        try:
+            method = self.lookup_method_fn(
+                self.module_config,
+                self.method_class,
+                attr)
+        except UndefinedMethodError:
+            raise AttributeError
+
+        #  Emulate descriptor behavior to allow methods to control if
+        #  they are properties or not.
+        if hasattr(method, '__get__'):
+            return method.__get__(None, self)
+
+        return method
 
     @classmethod
     def attach(cls, target, module_name=None):

web3/version.py

@@ -1,7 +1,46 @@
+from web3.method import (
+    AsyncMethod,
+    BlockingMethod,
+)
 from web3.module import (
     Module,
 )
 
+VERSION_MODULE_CONFIG = {
+    'node': {
+        'name': 'node',
+        'json_rpc_method': 'web3_clientVersion',
+        'is_property': True
+    },
+    'network': {
+        'name': 'network',
+        'json_rpc_method': 'net_version',
+        'is_property': True
+    },
+    'ethereum': {
+        'name': 'ethereum',
+        'json_rpc_method': 'eth_protocolVersion',
+        'is_property': True
+    },
+}
+
+
+class BaseVersion(Module):
+    module_config = VERSION_MODULE_CONFIG
+
+    @property
+    def api(self):
+        from web3 import __version__
+        return __version__
+
+
+class AsyncVersion(BaseVersion):
+    method_class = AsyncMethod
+
+
+class BlockingVersion(BaseVersion):
+    method_class = BlockingMethod
+
 
 class Version(Module):
     @property