PowerToys/doc/devdocs/logging.md

Logging

Logging plays an important part in determining bugs in our code. It provides context for the developers about where and when errors occur.

Where are the logs saved

• Most of the logs are saved under %LOCALAPPDATA%/Microsoft/PowerToys.
• For low-privilege processes (like preview handlers) the logs are saved under %USERPROFILE%/AppData/LocalLow/Microsoft/PowerToys.

Logs are normally in a subfolder with the module name as title.

The BugReportTool will take logs from both locations when executed.

Using a logger in a project

Spdlog

In C++ projects we use the awesome spdlog library for logging as a git submodule under the deps directory. To use it in your project, just include spdlog.props in a .vcxproj like this:

<Import Project="..\..\..\deps\spdlog.props" />

It'll add the required include dirs and link the library binary itself.

PowerToys Logger in ManagedCommon

For C# projects there is a static logger class in Managed Common called Logger.

To use it, add a project reference to ManagedCommon and add the following line of code to all the files using the logger:

using ManagedCommon;

In the Main function (or a function with a similar meaning (like App in a App.xaml.cs file)) you have to call InitializeLogger and specify the location where the logs will be saved (always use a path scheme similar to this example):

Logger.InitializeLogger("\\FancyZones\\Editor\\Logs");

For a low-privilege process you have to set the optional second parameter to true:

Logger.InitializeLogger("\\FileExplorer\\Monaco\\Logs", true);

The Logger class contains the following logging functions:

// Logs an error that the utility encountered
Logger.LogError(string message);
Logger.LogError(string message, Exception ex);
// Logs an error that isn't that grave
Logger.LogWarning(string message);
// Logs what the app is doing at the moment
Logger.LogInfo(string message);
// Like LogInfo just with infos important for debugging
Logger.LogDebug(string message);
// Logs the current state of the utility.
Logger.LogTrace();