Question

How do you reference the chained method’s object in that same method’s arguments. Let’s say you have a number of chained method calls that trim/substring a string like so:

str.Substring(varLen1).Substring(varLen2).Substring(1,##self##.Length-2)

The problem is that because the length of the string is now unknown and different from the original string’s length, how do I substring like in the last call (a substring where the index and length may depend on the string itself).

Thanks!

Answer 1

In short, no.

Though with an extension method you could capture ##self## and use a lambda to continue the expression.

public static TResult WithSelf<TSource, TResult> (this TSource x, Func<TSource, TResult> f)
{
    return f (x);
}

str.Substring (STDIN_PFX_FN.Length)
    .Trim (new char[] {'"', ' '})
    .WithSelf (x => x.Substring (1, x.Length - 2))

I tend to think that ends up more complicated to read and uglier and simply prefer to create a separate function.

str = Clean(str);

private string Clean (string str)
{
    str = str.Substring (STDIN_PFX_FN.Length).Trim (new char[] {'"', ' '});
    return str.Substring (1, str.Length - 2);
}