Settings

Plugin writers can use a wide variety of mechanisms in order to store and retrieve program settings. However, ReSharper provides its own infrastructure for keeping options. The advantages of this approach are that

Special arrangements exist which let the settings interact cleanly with options pages
A uniform API makes settings easier to use in your components
The settings infrastructure is conducive to settings migration, overlays, and other interactions

Declaring settings

In ReSharper, settings are kept in ordinary classes that have been decorated with some metadata. Let us take a look at an example of a settings class:

[SettingsKey(typeof(InternetSettings), "GitHub settings")]
public class GitHubSettings
{
  [SettingsEntry("", "GitHub username")]
  public string Username { get; set; }

  [SettingsEntry("", "GitHub password")]
  public string Password { get; set; }
}

As you can see, the above class is decorated with the SettingsKey attribute. This attribute is used to provide some information about what settings are kept, as well as their type. In the above example, the type of the settings is internet-related, and is indicated as such. You can explore ReSharper to find potential settings categories or, if you can't find a suitable type, simply use System.Reflection.Missing as the type.

Following the SettingsKey attribute, each property in the class is decorated with the SettingsEntry attribute. This attribute takes two parameters - the first being the default value for the property, the second the property's textual description.

Reading and Writing Settings

Rather than reading the settings directly, the correct approach is to bind settings to a particular context, and then operate on settings in this particular context. In order to bind settings, you first need an ISettingsStore, which can be injected into the required component via the constructor. Once you have acquired the ISettingsStore, you can bind it to a given data context (i.e. an IDataContext) using code similar to the following:

var boundSettings = mySettingsStore.BindToContextTransient(ContextRange.Smart((lt, _) => context));

Subsequently, you can use the GetKey() method of boundSettings to access the settings you need. For example:

var settings = boundSettings.GetKey<GitHubSettings>(SettingsOptimization.DoMeSlowly);

Now, when it comes to writing settings, there is a corresponding SetKey() method, but there is also a way to bind particular settings directly to UI (for example, when you are showing an options page). In order to do this, instead of injecting an ISettingsStore, you need to inject a class called OptionsSettingsSmartContext. This class has a SetBinding method that takes the following parameters:

A Lifetime entity, which you can also inject into your options page.
A reference to the UI control that needs to be bound. This is done differently for WPF and WinForms.
A lambda in the form (MySetting s) => s.SomeProperty that tells the smart context which property to bind.

For example, to bind GitHubSetting’s Username property to a WPF TextBox called usernameBox, you could write the following:

settings.SetBinding(lifetime, (GitHubSettings s) => s.Username, usernameBox, TextBox.TextProperty);

Things are a little different if you need to bind to a WinForms property: in thic case, you can use the WinFormsProperty helper class, particularly its Create method:

settings.SetBinding(lifetime, (GitHubSettings s) => s.Password, WinFormsProperty.Create(lifetime, passwordBox, box => box.Text, true));

A small note on data contexts: as you have seen, the BindToContextTransient takes a data context as a parameter, which is fine if you’ve got an Action, but a bit more challenging if you need to read a value elsewhere. In this case, you can do the following:

Inject a DataContexts (note the -s at the end) value into your component.
Use dataContexts.Empty as the parameter.

Working with Settings Layers

In addition to being able to manipulate settings individually, ReSharper also allows wholesale manipulation of settings using the concept of layers. A layer is simply a collection of settings that are stored in a particular file. The layering effect is such that layers above override the settings of layers below.

If you go into ReSharper → Manage Options… with an open solution, you will typically see three layers:

A personal layer
A team-shared layer
A settings file stored on this computer

The sum total of settings is held in a registrar that can be affected using an API that is available to plugin writers. For example, if you have a separate settings file that you want to programmatically inject, you can use the FileInjectedLayers shell component to inject this file using code similar to the following:

var host = context.GetData(DataConstants.InjectedLayersHost_IncludingHostItself);
var path = new FileSystemPath(filename);
fileInjectedLayers.InjectLayer(host.Value, path);

The above assumes that context is an available IDataContext and fileInjectedLayers is a shell component (acquired, e.g., by constructor injection) of type FileInjectedLayers.

Last modified: 04 July 2023