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doc/tutorial: add missing type annotation in LED example. Closes #356

This commit is contained in:
Sebastien Bourdeauducq 2016-03-29 14:53:52 +08:00
parent e6da8f778e
commit 1884b22528
1 changed files with 4 additions and 2 deletions
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6
doc/manual/getting_started_core.rst
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@ -43,8 +43,8 @@ A method or function running on the core device (which we call a "kernel") may c
Modify the code as follows: ::
def input_led_state():
return int(input("Enter desired LED state: "))
def input_led_state() -> TBool:
return bool(input("Enter desired LED state: "))
class LED(EnvExperiment):
def build(self):
@ -70,6 +70,8 @@ You can then turn the LED off and on by entering 0 or 1 at the prompt that appea
What happens is the ARTIQ compiler notices that the ``input_led_state`` function does not have a ``@kernel`` decorator and thus must be executed on the host. When the core device calls it, it sends a request to the host to execute it. The host displays the prompt, collects user input, and sends the result back to the core device, which sets the LED state accordingly.
RPC functions must always return a value of the same type. When they return a non-``None`` value, the compiler should be informed in advance of the type of the value, which is what the ``-> TBool`` annotation is for.
The ``break_realtime`` call is necessary to waive the real-time requirements of the LED state change (as the ``input_led_state`` function can take an arbitrarily long time). This will become clearer later as we explain timing control.
Algorithmic features