Standardize batch transform UI #1810
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Coverage 98.92% 98.92%
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Lines 15756 15783 +27
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+ Hits 15587 15614 +27
Misses 169 169
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josh146
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@josh146 I've just done a quick pass and left some initial questions. Very glad to have the new feature!
| @@ -414,11 +414,16 @@ def _validate_backprop_method(device, interface): | |||
| if interface in backprop_devices: | |||
| # TODO: need a better way of passing existing device init options | |||
| # to a new device? | |||
| expand_fn = device.expand_fn | |||
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Regarding the TODO above, I guess we need something like device.clone()?
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This is a todo we have kinda put on the backlog, just because the need for it disappears if we simply merge all the default qubit subclasses. Which should hopefully be doable now with qml.math!
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| def wrapper(qnode): | ||
| if isinstance(qnode, qml.Device): |
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I've gotten a bit tangled here; earlier we checked if the input was a device. But here, we're in the case where the input is a QNode, and with is a wrapper that can consider an argument that is a device?
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This is because the @batch_transform decorator is trying to be too clever 😬 I originally coded it up so that all of the following UIs work:
# inline syntax
qnode = qml.batch_transform(qnode, *transform_args)
tapes, fn = qml.batch_transform(tape, *transform_args)
dev = qml.batch_transform(dev, *transform_args)
# decorator syntax
qnode = qml.batch_transform(*transform_args)(qnode)
tapes, fn = qml.batch_transform(*transform_args)(tape)
dev = qml.batch_transform(*transform_args)(dev)The first three if statements cover the inline cases, this if statement covers the decorator syntax (hence the additional nested wrapper).
The reason for this complication is that
- I wanted to preserve the inline syntax, since
qml.metric_tensor(qnode, *targs)has worked like this for a very long time. - I also wanted to preserve the decorator syntax used by qfunc transforms and
qml.grad
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Ahh okay, thanks for clarifying that!
| @@ -414,11 +414,16 @@ def _validate_backprop_method(device, interface): | |||
| if interface in backprop_devices: | |||
| # TODO: need a better way of passing existing device init options | |||
| # to a new device? | |||
| expand_fn = device.expand_fn | |||
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| def wrapper(qnode): | ||
| if isinstance(qnode, qml.Device): |
There was a problem hiding this comment.
Ahh okay, thanks for clarifying that!
Context: #1809 standardizes
@qfunc_transformsto have the same consistent UI regardless of whether it is applied to qfuncs, tapes, or devices. This PR makes the equivalent change to the@batch_transformdecorator.Description of the Change:
The UI is now consistent with qfunc transforms
Batch transforms can be bound to devices
Fixes a bug found in the device class when creating a backprop device
Example:
Benefits: Makes the batch transform UI consistent with the qfunc transform UI, and fixes various UI bugs and edge cases.
Possible Drawbacks: n/a
Related GitHub Issues: n/a