Question

I just came across some code that overrides ToString() and returns some critical information (not just debug information). Users of this type called ToString() and parse that critical data.

My opinion, from reading various bits and pieces over the years, is that ToString() has a rather weak contract, i.e. override it (if you want) to display some meaningful stuff.

See I said display there? The code that I came across relied on the textual representation of instances of this type to be very specific; adding anything other than what’s expected would cause all sorts of problems.

So, my question is, if the textual representation of an object is critical, should ToString() be used or should a more explicit method/property be used, e.g. AsText?

Answer 1

Personally I share your concern. Microsoft’s documentation states that the ToString() method

[…] converts an object to its string representation so that it is suitable for display.

Oracle’s documentation for Java’s Object.toString() is even little stronger:

The result should be a concise but informative representation that is easy for a person to read.

I see these as strong indication that ToString() should convey information that is convenient for humans. A method that returns data that is to manipulated by other parts of the application should have a more informative name. In my opinion even AsText() is too generic.