C#

martin_hughes wrote:

Is there anything particularly wrong with using the following?

Dictionary<Type, Form> m_SingleInstanceForms = new Dictionary<Type, Form>();
protected Dictionary<Type, Form> SingleInstanceForms
{
    get { return this.m_SingleInstanceForms; }
}

protected virtual void ActivateChildForm<T>() where T : Form, new()
{
    if (!this.SingleInstanceForms.ContainsKey(typeof(T)))
    {
        T newForm = new T();
        this.SingleInstanceForms.Add(newForm);
        newForm.MdiParent = this;
    }
    Form formToActivate = this.SingleInstanceForms[typeof(T)];
    formToActivate.Show();
    formToActivate.Activate();
}

private void toolStripButton1_Click(object sender, EventArgs e)
{
    this.ActivateChildForm<uxLoginForm>();
}

if (!this.SingleInstanceForms.ContainsKey(typeof(T)))
{
    T newForm = new T();
    this.SingleInstanceForms.Add(typeof(T),newForm);
    newForm.MdiParent = this;
}
else if (this.SingleInstanceForms[typeof(T)].IsDisposed)
{
    T newForm = new T();
    this.SingleInstanceForms[typeof(T)] = newForm;
    newForm.MdiParent = this;
}

protected virtual void ActivateChildForm<T>() where T : Form, new()

martin_hughes wrote:

I guess that the where T : Form limits what can be passed in as

martin_hughes wrote:

but what's the new() about?

martin_hughes wrote:

But doing so looks a bit errrmm inellegant

if (!this.SingleInstanceForms.ContainsKey(typeof(T)))
{
    T newForm = new T();
    newForm.MdiParent = this;
    newForm.FormClosing += new FormClosingEventHandler(delegate (object sender, FormClosingEventArgs e)
        {
            Form senderForm = (sender as Form);
            // Tidy up...
            senderForm.Dispose();
            this.SingleInstanceForms.Remove(senderForm.GetType());
        }
    ));
    this.SingleInstanceForms.Add(typeof(T), newForm);
}
...