Arrow key commands involve repetitive entry macros

[henryksloan]

This came up during the implementation of #245. The implementation of nudge features (with single-arrow inputs and two-arrow inputs, and with shift-held variants of each) is as follows:

entry! {action=DocumentMessage::NudgeSelectedLayers(SHIFT_NUDGE_AMOUNT, -SHIFT_NUDGE_AMOUNT), key_down=KeyArrowUp, modifiers=[KeyShift, KeyArrowRight]},
entry! {action=DocumentMessage::NudgeSelectedLayers(0., -SHIFT_NUDGE_AMOUNT), key_down=KeyArrowUp, modifiers=[KeyShift]},
entry! {action=DocumentMessage::NudgeSelectedLayers(-SHIFT_NUDGE_AMOUNT, SHIFT_NUDGE_AMOUNT), key_down=KeyArrowDown, modifiers=[KeyShift, KeyArrowLeft]},
entry! {action=DocumentMessage::NudgeSelectedLayers(SHIFT_NUDGE_AMOUNT, SHIFT_NUDGE_AMOUNT), key_down=KeyArrowDown, modifiers=[KeyShift, KeyArrowRight]},
entry! {action=DocumentMessage::NudgeSelectedLayers(0., SHIFT_NUDGE_AMOUNT), key_down=KeyArrowDown, modifiers=[KeyShift]},
entry! {action=DocumentMessage::NudgeSelectedLayers(-SHIFT_NUDGE_AMOUNT, -SHIFT_NUDGE_AMOUNT), key_down=KeyArrowLeft, modifiers=[KeyShift, KeyArrowUp]},
entry! {action=DocumentMessage::NudgeSelectedLayers(-SHIFT_NUDGE_AMOUNT, SHIFT_NUDGE_AMOUNT), key_down=KeyArrowLeft, modifiers=[KeyShift, KeyArrowDown]},
entry! {action=DocumentMessage::NudgeSelectedLayers(-SHIFT_NUDGE_AMOUNT, 0.), key_down=KeyArrowLeft, modifiers=[KeyShift]},
entry! {action=DocumentMessage::NudgeSelectedLayers(SHIFT_NUDGE_AMOUNT, -SHIFT_NUDGE_AMOUNT), key_down=KeyArrowRight, modifiers=[KeyShift, KeyArrowUp]},
entry! {action=DocumentMessage::NudgeSelectedLayers(SHIFT_NUDGE_AMOUNT, SHIFT_NUDGE_AMOUNT), key_down=KeyArrowRight, modifiers=[KeyShift, KeyArrowDown]},
entry! {action=DocumentMessage::NudgeSelectedLayers(SHIFT_NUDGE_AMOUNT, 0.), key_down=KeyArrowRight, modifiers=[KeyShift]},
entry! {action=DocumentMessage::NudgeSelectedLayers(-NUDGE_AMOUNT, -NUDGE_AMOUNT), key_down=KeyArrowUp, modifiers=[KeyArrowLeft]},
entry! {action=DocumentMessage::NudgeSelectedLayers(NUDGE_AMOUNT, -NUDGE_AMOUNT), key_down=KeyArrowUp, modifiers=[KeyArrowRight]},
entry! {action=DocumentMessage::NudgeSelectedLayers(0., -NUDGE_AMOUNT), key_down=KeyArrowUp},
entry! {action=DocumentMessage::NudgeSelectedLayers(-NUDGE_AMOUNT, NUDGE_AMOUNT), key_down=KeyArrowDown, modifiers=[KeyArrowLeft]},
entry! {action=DocumentMessage::NudgeSelectedLayers(NUDGE_AMOUNT, NUDGE_AMOUNT), key_down=KeyArrowDown, modifiers=[KeyArrowRight]},
entry! {action=DocumentMessage::NudgeSelectedLayers(0., NUDGE_AMOUNT), key_down=KeyArrowDown},
entry! {action=DocumentMessage::NudgeSelectedLayers(-NUDGE_AMOUNT, -NUDGE_AMOUNT), key_down=KeyArrowLeft, modifiers=[KeyArrowUp]},
entry! {action=DocumentMessage::NudgeSelectedLayers(-NUDGE_AMOUNT, NUDGE_AMOUNT), key_down=KeyArrowLeft, modifiers=[KeyArrowDown]},
entry! {action=DocumentMessage::NudgeSelectedLayers(-NUDGE_AMOUNT, 0.), key_down=KeyArrowLeft},
entry! {action=DocumentMessage::NudgeSelectedLayers(NUDGE_AMOUNT, -NUDGE_AMOUNT), key_down=KeyArrowRight, modifiers=[KeyArrowUp]},
entry! {action=DocumentMessage::NudgeSelectedLayers(NUDGE_AMOUNT, NUDGE_AMOUNT), key_down=KeyArrowRight, modifiers=[KeyArrowDown]},
entry! {action=DocumentMessage::NudgeSelectedLayers(NUDGE_AMOUNT, 0.), key_down=KeyArrowRight},

This is obviously verbose, repetitive, and error-prone. @TrueDoctor and I discussed possible options for macros, but an elegant macro has yet to be laid out or implemented. It would probably involve replacing some placeholders like $x and $y with 0., 1. or -1., in such a way that it can be involved in an expression like 10. * $x. It should also support modifiers, to allow shift-held variants as above. The above macros should probably correspond to two macros, one with the shift modifier and with * 10. attached to $x and $y.

[0HyperCube]

Also relevant to #701.

[Keavon]

Closing because we might want to port this to a text-based config file where a loop structure won't even be possible.