ASP.Net caching manager

I have a Cache Helper Class.

using System;
using System.Web;

public static class CacheHelper
{
    /// 
    /// Insert value into the cache using
    /// appropriate name/value pairs
    /// 
    /// Type of cached item
    /// Item to be cached
    /// Name of item
    public static void Add(T o, string key) 
    {
        // NOTE: Apply expiration parameters as you see fit.
        // I typically pull from configuration file.

        // In this example, I want an absolute
        // timeout so changes will always be reflected
        // at that time. Hence, the NoSlidingExpiration.
        HttpContext.Current.Cache.Insert(
            key,
            o,
            null,
            DateTime.Now.AddMinutes(1440),
            System.Web.Caching.Cache.NoSlidingExpiration);
    }

    /// 
    /// Remove item from cache
    /// 
    /// Name of cached item
    public static void Clear(string key)
    {
        HttpContext.Current.Cache.Remove(key);
    }

    /// 
    /// Check for item in cache
    /// 
    /// Name of cached item
    /// 
    public static bool Exists(string key)
    {
        return HttpContext.Current.Cache[key] != null;
    }

    /// 
    /// Retrieve cached item
    /// 
    /// Type of cached item
    /// Name of cached item
    /// Cached value. Default(T) if 
    /// item doesn't exist.
    /// Cached item as type
    public static bool Get(string key, out T value) 
    {
        try
        {
            if (!Exists(key))
            {
                value = default(T);
                return false;
            }

            value =  (T) HttpContext.Current.Cache[key];
        }
        catch
        {
            value = default(T);
            return false;
        }

        return true;
    }
}

and usage:

```
string key = "EmployeeList";
List employees;

if (!CacheHelper.Get(key, out employees))
{
employees = DataAccess.GetEmployeeList();
CacheHelper.Add(employees, key);
Message.Text =
"Employees not

/// 
/// Insert value into the cache using
/// appropriate name/value pairs
/// 
/// Type of cached item
/// Item to be cached
/// Name of item
public static void Add(T o, string key)

I think this signature would be more useful like this:

/// 
/// Insert value into the cache using
/// appropriate name/value pairs.
/// 
/// Type of cached item (inferred from usage).
/// A string used to uniquely identify the added value.
/// Item/value to be cached.
public static void Add(string key, T value)

This is misleading:

/// 
/// Remove item from cache
/// 
/// Name of cached item
public static void Clear(string key)
{
    HttpContext.Current.Cache.Remove(key);
}

Clear is usually a parameterless method that clears a container's contents. This method should be named Remove.

/// 
/// Check for item in cache
/// 
/// Name of cached item
/// 
public static bool Exists(string key)
{
    return HttpContext.Current.Cache[key] != null;
}

"Check for item in cache" doesn't really say what's going on. I realize it's trivially inferred from the method's name, but "Checks for existence of specified key in cache." would be totally unambiguous.

public static bool Get(string key, out T value)

I don't like the implementation of that method very much, there are too many exit points, some being redundant. Consider something like this:

public static bool TryGet(string key, out T value) 
{
    bool result;

    try
    {
        if (Exists(key))
        {
            value =  (T)HttpContext.Current.Cache[key];
            result = true;
        }
    }
    catch(InvalidCastException)
    {
        value = default(T);
    }

    return result;
}

StackExchange Code Review Q#49541, answer score: 12