Parameter is null by default. No value is given. Code says it is not null.

[tcak via Digitalmars-d-learn]

I have written a function as follows:

public bool setCookie(
        string name,
        string value,
        long maxAgeInSeconds = long.min,
        string expiresOnGMTDate=null,
        string path=null,
        string domain=null,
        bool secure=false
) shared{
        // if headers are sent already, leave
        if( headersSent ) return false;

        // name cannot be empty
        if( (name is null) || (name.length <= 0) ) return false;

        writeln(
                "Name: ", name,
                "  Max Age: ", maxAgeInSeconds,
                "  Expires null: ", (expiresOnGMTDate == null),
                "  Path equals null: ", (path == null),
                "  Domain null: ", (domain is null)
        );

        return true;
}



Here is the testing code:

responseObject.setCookie( "A", "B" );
auto now = std.datetime.Clock.currTime().toSimpleString();
//writeln("Now |", now, "|");
responseObject.setCookie( "Response Time", now );


Here is the results:

Name: A  Max Age: -9223372036854775808  Expires null: true  Path 
equals null: true  Domain null: true

Name: Response Time  Max Age: -9223372036854775808  Expires null: 
true  Path equals null: false  Domain null: false


I don't know what is happening though, somehow path and domain 
parameters in second use of function are not null even I haven't 
given any value to them.

If I uncomment the "writeln" line in test code, it turns normal. 
I am so much confused right now. What is happening here?