Empty registers cause exceptions even when applying appropriate multi-qubit gates about projectq HOT 6 CLOSED

Do you know a nice way to fix this issue? We could check for empty lists directly in the or-operator or, alternatively, allow commands with no target qubits and then throw them out. Both don't seem very graceful...

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There is a partial fix, just for controls, in #50

My wild idea for how to fix it is to move the engine-selection out of the qubits and into blocks like this:

with eng.pipe_commands_into_me():
    ...

But I'm still debating the strengths of that approach. It nicely simplifies the Dagger/Control/Loop/Compute cases, but it deals poorly with generators, coroutines, and async methods (since they turn this intended-to-be-lexical scoping mechanisms into a dynamical scoping mechanism).

I will send you an invite to a doc where I'm listing out things I want to propose.

from projectq.

Well, the controls part is no longer an issue but thanks for catching that!
Yes, I'm also wondering if this would not introduce too much boilerplate code. After all, having a nice and easy-to-learn syntax is a huge plus :)

Concerning the doc: Great, thanks.

from projectq.

Do you have a gmail address? It's in a google doc that I can only share with google accounts.

from projectq.

Yes, I sent you an e-mail.

from projectq.

We currently don't have any example where an application of a gate to an empty list would make sense. Our current design does not prohibit implementing this if it is ever needed for a specific case.

I am closing this issue now. If there is a gate implemented where the application to an empty list make sense, please open a new issue and we could then discuss adding this feature for that explicit gate.

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