Function Repository Resource:

CreatePackageEventHandler

Source Notebook

Create an event handler that evaluates an expression when a package is loaded

Contributed by: Richard Hennigan (Wolfram Research)

ResourceFunction["CreatePackageEventHandler"][code,"context`"]

creates an event handler that evaluates code when "context`" starts loading.

ResourceFunction["CreatePackageEventHandler"][code,"context`",After]

creates an event handler that evaluates code when "context`" finishes loading.

Details and Options

ResourceFunction["CreatePackageEventHandler"][code,"context`",Before] is equivalent to ResourceFunction["CreatePackageEventHandler"][code,"context`"].

Examples

Basic Examples (4)

Print a message when a package is first loaded:

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$ResourceFunction["CreatePackageEventHandler"][ Print["Loading ComputerArithmetic`\[Ellipsis]"], "ComputerArithmetic`"]$

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Print a message when a package finishes loading:

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ResourceFunction["CreatePackageEventHandler"][
Print[Length[Names["Notation`*"]], " symbols loaded in Notation`."], "Notation`", After]

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Check to see what file is used to load a context:

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Get timing for loading a package:

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(* Evaluate this cell to get the example input *) CloudGet["https://www.wolframcloud.com/obj/27c884bf-cc5b-4204-a69b-b57c2be37222"]

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Possible Issues (2)

An auto-loading context that is already loaded will no longer trigger the loading event:

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$NetModel["LeNet Trained on MNIST Data"][{\!$\* GraphicsBox[ TagBox[RasterBox[CompressedData[" 1:eJxTTMoPSmNiYGAo5gASQYnljkVFiZXBAkBOaF5xZnpeaopnXklqemqRRRJI mQwU/6cK2MHQhEtqiTTTJVxyQUy633BIneZSeolLWwSTBS6pP1ZM+bjkzjEJ 4ZL6X81kjkvqKydTHS65L0y45c4wMS3FJdfOxHRtcW3tkY/Y5cBA+T5WOaPk 5GgmJkNMOQWwW/6FMMliyqWB5X46MlliNTPo//+JTExbMOU+Ad0h683ElP8P U+73fCGQM4XuYPHD//97LZmYLPdhlRrUAABgHMjK "], {{0, 28}, {28, 0}}, {0, 255}, ColorFunction->GrayLevel], BoxForm`ImageTag[ "Byte", ColorSpace -> Automatic, Interleaving -> None], Selectable->False], DefaultBaseStyle->"ImageGraphics", ImageSizeRaw->{28, 28}, PlotRange->{{0, 28}, {0, 28}}]$, \!$\* GraphicsBox[ TagBox[RasterBox[CompressedData[" 1:eJxTTMoPSmNiYGAo5gASQYnljkVFiZXBAkBOaF5xZnpeaopnXklqemqRRRJI mQwU/x9IsJWBKew2dql3okzMzH6/sMr5M7tPNGWeglXOQPf//yPiZdjlgMI7 mbHKVTOVQQkM8FCaef+v3dIih7HIfQphnnKCmdntBzYzdzKLizEzM+/DJvdD hxnoP+xueafNxCvJwWSG3S0SV/+7M/tikbvAzHzyP1AOi5lvNJj9fwPlVJdj ytUzMx8HUu7xWIw0ZdJ49f/PJUWTL5hyTMwT//+/xMxcgkUfE/Ou/92KzKGf sMqpGLBzTb6MRer/Sh1gmGDzG/0AACEauS8= "], {{0, 28}, {28, 0}}, {0, 255}, ColorFunction->GrayLevel], BoxForm`ImageTag[ "Byte", ColorSpace -> Automatic, Interleaving -> None], Selectable->False], DefaultBaseStyle->"ImageGraphics", ImageSizeRaw->{28, 28}, PlotRange->{{0, 28}, {0, 28}}]$, \!$\* GraphicsBox[ TagBox[RasterBox[CompressedData[" 1:eJxTTMoPSmNiYGAo5gASQYnljkVFiZXBAkBOaF5xZnpeaopnXklqemqRRRJI mQwU/x9IsN/BdW1Vstx8LFK7eZgYmYBAcepvNJkvG/mZIHJMTLfR5OaBBAtX r44CKqn4hSK1TRgoZQNipQEZp5ClPpoCRSr+gJiXgarykeWWAqUqoSalocrd 52ViCnwJMx5VLpeJyQVufyOK3Fo2JqYWOM+WiWkFkjZGRjs4p4mRkXE5nPcp GegQGOeXM9BZ1vth3EAgT3I+lHMOyLE7Adf3y4uJqeY1hP3MFShXhbDuTwgT 0ywIa5s9Wnh+AnIFErYBgSVIRrz4G0LumxoTFIDiQaztPzLIQ5JzPogi9f+Z NkzOof77fzTwY1EcSKps5y90GToCAMITbxU= "], {{0, 28}, {28, 0}}, {0, 255}, ColorFunction->GrayLevel], BoxForm`ImageTag[ "Byte", ColorSpace -> Automatic, Interleaving -> None], Selectable->False], DefaultBaseStyle->"ImageGraphics", ImageSizeRaw->{28, 28}, PlotRange->{{0, 28}, {0, 28}}]$}]$

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Run in a new session instead:

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$ResourceFunction["LocalEvaluate"][ NetModel["LeNet Trained on MNIST Data"][{\!$\* GraphicsBox[ TagBox[RasterBox[CompressedData[" 1:eJxTTMoPSmNiYGAo5gASQYnljkVFiZXBAkBOaF5xZnpeaopnXklqemqRRRJI mQwU/6cK2MHQhEtqiTTTJVxyQUy633BIneZSeolLWwSTBS6pP1ZM+bjkzjEJ 4ZL6X81kjkvqKydTHS65L0y45c4wMS3FJdfOxHRtcW3tkY/Y5cBA+T5WOaPk 5GgmJkNMOQWwW/6FMMliyqWB5X46MlliNTPo//+JTExbMOU+Ad0h683ElP8P U+73fCGQM4XuYPHD//97LZmYLPdhlRrUAABgHMjK "], {{0, 28}, {28, 0}}, {0, 255}, ColorFunction->GrayLevel], BoxForm`ImageTag[ "Byte", ColorSpace -> Automatic, Interleaving -> None], Selectable->False], DefaultBaseStyle->"ImageGraphics", ImageSizeRaw->{28, 28}, PlotRange->{{0, 28}, {0, 28}}]$, \!$\* GraphicsBox[ TagBox[RasterBox[CompressedData[" 1:eJxTTMoPSmNiYGAo5gASQYnljkVFiZXBAkBOaF5xZnpeaopnXklqemqRRRJI mQwU/x9IsJWBKew2dql3okzMzH6/sMr5M7tPNGWeglXOQPf//yPiZdjlgMI7 mbHKVTOVQQkM8FCaef+v3dIih7HIfQphnnKCmdntBzYzdzKLizEzM+/DJvdD hxnoP+xueafNxCvJwWSG3S0SV/+7M/tikbvAzHzyP1AOi5lvNJj9fwPlVJdj ytUzMx8HUu7xWIw0ZdJ49f/PJUWTL5hyTMwT//+/xMxcgkUfE/Ou/92KzKGf sMqpGLBzTb6MRer/Sh1gmGDzG/0AACEauS8= "], {{0, 28}, {28, 0}}, {0, 255}, ColorFunction->GrayLevel], BoxForm`ImageTag[ "Byte", ColorSpace -> Automatic, Interleaving -> None], Selectable->False], DefaultBaseStyle->"ImageGraphics", ImageSizeRaw->{28, 28}, PlotRange->{{0, 28}, {0, 28}}]$, \!$\* GraphicsBox[ TagBox[RasterBox[CompressedData[" 1:eJxTTMoPSmNiYGAo5gASQYnljkVFiZXBAkBOaF5xZnpeaopnXklqemqRRRJI mQwU/x9IsN/BdW1Vstx8LFK7eZgYmYBAcepvNJkvG/mZIHJMTLfR5OaBBAtX r44CKqn4hSK1TRgoZQNipQEZp5ClPpoCRSr+gJiXgarykeWWAqUqoSalocrd 52ViCnwJMx5VLpeJyQVufyOK3Fo2JqYWOM+WiWkFkjZGRjs4p4mRkXE5nPcp GegQGOeXM9BZ1vth3EAgT3I+lHMOyLE7Adf3y4uJqeY1hP3MFShXhbDuTwgT 0ywIa5s9Wnh+AnIFErYBgSVIRrz4G0LumxoTFIDiQaztPzLIQ5JzPogi9f+Z NkzOof77fzTwY1EcSKps5y90GToCAMITbxU= "], {{0, 28}, {28, 0}}, {0, 255}, ColorFunction->GrayLevel], BoxForm`ImageTag[ "Byte", ColorSpace -> Automatic, Interleaving -> None], Selectable->False], DefaultBaseStyle->"ImageGraphics", ImageSizeRaw->{28, 28}, PlotRange->{{0, 28}, {0, 28}}]$}], HandlerFunctions -> <| "PrintOutputGenerated" -> (Print[ReleaseHold[#PrintOutput]] &)|>, Initialization :> (ResourceFunction["CreatePackageEventHandler"][ Print["Loading NeuralNetworks` from ", $InputFileName], "NeuralNetworks`"]) ]$