In current C# a collection initialization can be done like this:

var result = new Dictionary<string, string>();
result.Add("index1", "value1");
result.Add("index2", "value2");

or key - value pairs can be added during initialization

var result = new Dictionary<string, string>() 
{
	{"index1", "value1"},
	{"index2", "value2"}
};

With C# 6.0 values at specific indices can be initialized like this:

var result = new Dictionary<string, string>() 
{
	["index1"] = "value1",
	["index2"] = "value2"
};

It’s a shorthand but not so much! I don’t see much value in this notation but I’m sure in time it will prove itself. I don’t think the guys in the language team are just adding random features!

It’s a shorthand for writing methods. The body now can be written just like a Lambda expression as shown in Log2 method below:

public string Log(string timestamp, string application, string error, string status)
{
    return string.Format("[Timestamp: \{timestamp}], Application: [\{application}], Error: [\{error}], Status [\{status}]");
}

public string Log2(string timestamp, string application, string error, string status) => string.Format("[Timestamp: \{timestamp}], Application: [\{application}], Error: [\{error}], Status [\{status}]");

It may come in handy for helper methods. The only benefit I can see is getting rid of opening and closing curly braces which generally don’t bother me much. But I know lots of people trying to avoid curly braces as much as possible. I’m sure this feature will be popular among them.

There are 2 improvements on exception handling:

1. Exception filters
2. Using await in catch and finally blocks

Exception Filters

Visual Basic and F# already have this feature and now C# has it too! the way it works is basically defining a condition for the catch block (example taken from Channel 9 video):

try
{

}
catch(ConfigurationException e) if (e.IsSevere)
{

}

I think it can make exception handling more modular. Also it’s better than catching and rethrowing in terms of we don’t lose information about the original exception.

Using await in catch and finally blocks

Like most people I hadn’t noticed we couldn’t do that already! Apparently it was just a flaw in the current implementation and they closed that gap with this version

try
{

}
catch(ConfigurationException e) if (e.IsSevere)
{
	await LogAsync(e);
}
finally
{
	await CloseAsync();
}