Custom lazy magics do not show help (?) until they are imported

Commencez par InteractiveShell et le point d’entrée register_lazy du magic manager, puis reproduisez les exemples duals de line/cell et de time intégré avec run_cell. Suivez la manière dont la recherche d’aide et le lazy registration résolvent chaque magic form ; le travail est terminé lorsque la première demande d’aide fonctionne de manière cohérente et que l’écrasement d’une forme préserve l’autre comportement intégré.

Prior to 9.17.0 it did not work at all. Since 9.17.0 it sometimes works on the second attempt (depending on the order of registration):

import sys, types
from IPython.core.interactiveshell import InteractiveShell
from IPython.core.magic import Magics, cell_magic, line_magic, magics_class


@magics_class
class LineHalf(Magics):
    @line_magic
    def dual(self, line):
        """The line half of %dual."""


@magics_class
class CellHalf(Magics):
    @cell_magic
    def dual(self, line, cell):
        """The cell half of %%dual."""


sys.modules["provider"] = provider = types.ModuleType("provider")
provider.LineHalf, provider.CellHalf = LineHalf, CellHalf

ip = InteractiveShell()
ip.magics_manager.register_lazy("dual", "provider:LineHalf", "line")
ip.magics_manager.register_lazy("dual", "provider:CellHalf", "cell")

ip.run_cell("%%dual?")   # does not work "Object `%%dual` not found."
ip.run_cell("%%dual?")   # works, shows "Docstring: The cell half of %%dual."

If we swap registration order neither works:

import sys, types
from IPython.core.interactiveshell import InteractiveShell
from IPython.core.magic import Magics, cell_magic, line_magic, magics_class


@magics_class
class LineHalf(Magics):
    @line_magic
    def dual(self, line):
        """The line half of %dual."""


@magics_class
class CellHalf(Magics):
    @cell_magic
    def dual(self, line, cell):
        """The cell half of %%dual."""


sys.modules["provider"] = provider = types.ModuleType("provider")
provider.LineHalf, provider.CellHalf = LineHalf, CellHalf

ip = InteractiveShell()
ip.magics_manager.register_lazy("dual", "provider:CellHalf", "cell")
ip.magics_manager.register_lazy("dual", "provider:LineHalf", "line")

ip.run_cell("%%dual?")   # does not work "Object `%%dual` not found."
ip.run_cell("%%dual?")   #  does not work "Object `%%dual` not found."

Also, there are issues when overwriting built-in dual magic with say only a line magic:

import sys, types
from IPython.core.interactiveshell import InteractiveShell
from IPython.core.magic import Magics, line_magic, magics_class


@magics_class
class MyMagics(Magics):
    @line_magic
    def time(self, line):
        """My own %time."""


sys.modules["provider"] = provider = types.ModuleType("provider")
provider.MyMagics = MyMagics

ip = InteractiveShell()
ip.magics_manager.register_lazy("time", "provider:MyMagics")

ip.run_cell("time?")            # my own %time
ip.run_cell("%%time?")          # expected: IPython's %%time docs
ip.run_cell("%%time\npass")     # expected: a wall time report