...is to be most productive with whatever is in front of him. May it be Java, C, .Net, ROR, PHP, etc...
With whatever tool, framework, 3rd party library, etc etc etc...
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It's not a battle of which language is better or which framework is better. The real test is how a programmer can adapt to any system, any framework, any tool at a given time and deadline. How fast and efficient one can learn the new language or framework and get things done and catch up on deadlines.
In the real world, business applications are complex. It is usually a combination of platforms and systems. You can't say - "I can't work on that part coz I don't know Hibernate or C++ or Unix...". Sometimes you don't have any choice but to learn it.
Just a little glimpse of what's out there.