Re: Scope of your developers skills
Most developers will learn what they learn as they need it or get traning in anticipation of the skills they think they will need.
Most developers will know enough about a language, programming idiom, development environment, platform, hardware to write something even if they are not an expert in that language, if they apply for that position.
On the job they will learn the extra they need to be proficient in what they do in that language.
Most developers will specialise in one or two languages but can write software in many more.
Depending apon what my job asks of me, i will learn those skills.
As for the skillsets the companies ask for on their job spec; this is a wish list only and most will settle for far less. They want employees with the capacity to learn (and not just by rote).
If you believe everything you read, you better not read. ~ Japanese Proverb
If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain