The "Expert/Master At (Language)" Point
pmiller2: Some necessary but not sufficient criteria for our intrepid programmer to consider himself a master of his language:* He's written a non-toy compiler for the language.* He knows how to choose between more or less semantically equivalent ways of writing the same code because he understands the tradeoffs involved.* He's explored many or most of the dark and mysterious corners of the language and knows when and when not to invoke them in production code.* He is familiar with the contents of the standard library and uses it whenever appropriate.* Knuth is his homeboy.That's all I can think of for now.