REPL to the rescue
October 10th, 2007 by proj
From the book Practical Common Lisp
“Debugging a program running on a $100M piece of hardware that is 100 million miles away is an interesting experience. Having a read-eval-print loop running on the spacecraft proved invaluable in finding and fixing the problem.”
We have been recognizing a similar benefit on the server side of the MMO I have been working on recently. Due to the fact that most of the game is implemented in Python and a remote interface is exposed to the hosted interpreter it has saved me countless hours of wasted debugging time.
It’s especially important in large scale service development to ensure that a source level debugger is not used as a crutch during development. This usually leads to an architecture that supports tracing, run-time probes and some sort of console. Using an interactive language at the core gives you an additional tool that should not be overlooked for the value that it adds to the production cycle.
Of course Python in no way is the originator or sole proprietor of the REPL but it is one of the aspects of the environment where I feel GVR did get it right. Every successive version of Python that is introduced (that isn’t focused mainly on fixing bad design decisions) seems to introduce much heralded ideas that have a striking similiarity to languages from the long before the beginning of time.
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