def evaluate_impl(expression, params=None):
'''Implementation of CalculatorImpl::evaluate(), also shared by
FunctionImpl::call(). In the latter case, `params` are the parameter
values passed to the function; in the former case, `params` is just an
empty list.'''
which = expression.which()
if which == 'literal':
return capnp.Promise(expression.literal)
elif which == 'previousResult':
return read_value(expression.previousResult)
elif which == 'parameter':
assert expression.parameter < len(params)
return capnp.Promise(params[expression.parameter])
elif which == 'call':
call = expression.call
func = call.function
# Evaluate each parameter.
paramPromises = [evaluate_impl(param, params) for param in call.params]
joinedParams = capnp.join_promises(paramPromises)
# When the parameters are complete, call the function.
ret = (joinedParams.then(lambda vals: func.call(vals)).then(
lambda result: result.value))
return ret
else:
raise ValueError("Unknown expression type: " + which)
def test_then_args():
capnp.Promise(0).then(lambda x: 1)
with pytest.raises(Exception):
capnp.Promise(0).then(lambda: 1)
with pytest.raises(Exception):
capnp.Promise(0).then(lambda x, y: 1)
capnp.getTimer().after_delay(1).then(lambda: 1) # after_delay is a VoidPromise
with pytest.raises(Exception):
capnp.getTimer().after_delay(1).then(lambda x: 1)
client = capability.TestInterface._new_client(Server())
client.foo(i=5).then(lambda x: 1)
with pytest.raises(Exception):
client.foo(i=5).then(lambda: 1)
with pytest.raises(Exception):
client.foo(i=5).then(lambda x, y: 1)
def test_timer():
global test_timer_var
test_timer_var = False
def set_timer_var():
global test_timer_var
test_timer_var = True
capnp.getTimer().after_delay(1).then(set_timer_var).wait()
assert test_timer_var is True
test_timer_var = False
promise = capnp.Promise(0).then(lambda x: time.sleep(.1)).then(
lambda x: time.sleep(.1)).then(lambda x: set_timer_var())
canceller = capnp.getTimer().after_delay(1).then(lambda: promise.cancel())
joined = capnp.join_promises([canceller, promise])
joined.wait()