What's the purpose of the components IContainer generated by the Winforms designer?

Question

When you create a new form in Visual Studio, the designer generates the following code in the .Designer.cs file:

  /// <summary>
  /// Required designer variable.
  /// </summary>
  private System.ComponentModel.IContainer components = null;

  /// <summary>
  /// Clean up any resources being used.
  /// </summary>
  /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
  protected override void Dispose(bool disposing)
  {
     if (disposing && (components != null))
     {
        components.Dispose();
     }
     base.Dispose(disposing);
  }

What is the purpose of the components variable? My theory is that I should use it for any IDisposable classes my form owns which I create outside of Designer (since Dispose is already being implemented by the Designer).

So, for example, if my form owns a font, I could make sure it gets disposed by adding it to components like this:

  public partial class Form1 : Form
  {
      Font coolFont;

      public Form1()
      {
          InitializeComponent();
          this.coolFont = new Font("Comic Sans", 12);
          components.Add(this.coolFont);
      }
  }

Is that what it's for? I haven't been able to find any documentation or information about this.

Answer 1

When you add non-UI components to the form (such as a Timer component), components will be the parent of those compoments. The code in the designer file makes sure that these components are disposed of when the form is disposed. If you have not added any such components to the form in design time, components will be null.

Since components is designer generated, and will be null if you have no non-UI compoments on the form (in design time), I would personally opt for managing those components in some other way, disposing them on form close or something like that.