27
votes
Accepted
How to respond to the two-handed approach to swapping
Don't overcomplicate things. Your first instinct, that the computer only has one hand, was the correct one.
This is a regular problem that new teachers have, and it sometimes takes a few years of ...
- 32.8k
22
votes
How to respond to the two-handed approach to swapping
Re-evaluate what you think is "right", because you aren't
but isn't right in computer science
This is simply incorrect. Your student can create two variables called ...
- 1,072
16
votes
How to respond to the two-handed approach to swapping
Your problem is that you tried to let your student "program" without establishing a language. Thus they were free to write their own "language" in which you can do two things at ...
- 1,433
10
votes
When should concurrency and parallel multi-processing concepts be introduced?
If we don't introduce parallel/concurrent thinking early, our students can develop a sequential mindset that makes it hard for them to make the shift later. The rest of this is in the context of a ...
- 1,011
9
votes
Accepted
Why is the critical-section problem always presented with code in infinite loops?
One reason infinite loops are used could be so the problem can't be solved by letting one thread complete the code before the other thread starts it. With infinite loops, no thread ever completes the ...
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5
votes
How to respond to the two-handed approach to swapping
This question reminds me of when a student failed to understand why a third variable was needed to exchange the value of two variables (i.e. to swap A and B, C=A, A=B, B=C). I managed to illustrate ...
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5
votes
When should concurrency and parallel multi-processing concepts be introduced?
We're introducing some aspects of parallel processing quite early on in Scratch. Each sprite has its own script which appears to execute in parallel with those of the others. Scratch has a broadcast ...
- 1,256
5
votes
Why is the critical-section problem always presented with code in infinite loops?
"processes that run and enter critical sections ... where the code is not in an infinite loop"
Processes are generally components of a reactive system (like an OS) that are designed to be non-...
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4
votes
Could you recommend books on concurrent programming?
Concurrent programming is easy, synchronisation is hard.
Have a look at this video for an alternative to synchronisation: https://www.youtube.com/watch?v=2yXtZ8x7TXw
When you have to synchronize
Use ...
- 10.7k
4
votes
How to respond to the two-handed approach to swapping
They took both their hands, picked up the second and fourth pencils (each in one hand), and swapped them! That works in reality... but isn't right in computer science.
It depends on your paradigm. ...
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3
votes
Could you recommend books on concurrent programming?
Since the OP asked about functional programming, so I would highly recommend you to read "Learning Concurrent Programming in Scala" by Aleksandar Prokopec, (2014). All the examples for this book are ...
- 559
3
votes
How to respond to the two-handed approach to swapping
I do the swap example pretending to have two largish (2-hands-to-lift) boxes side-by-side on a desk (with only enough room for two boxes). After we lift the first we have to look for a place to put it,...
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3
votes
How to respond to the two-handed approach to swapping
In thinking about this, and especially the answer of Graham, I think that what we really do in the standard three step process is a two handed swap without thinking of it. So, it is a failure of the ...
- 35.8k
3
votes
How to respond to the two-handed approach to swapping
Analogies & metaphors are imperfect, so let's share the expectation that they are just illustrative.
Rules of what is possible (and not) are very important, and we can compare the rules of pencils ...
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2
votes
How to respond to the two-handed approach to swapping
Graham pointed out that the assumtions of the question are wrong. And Peter Cordes elaborated a bit in the comments.
Considering a target VLIW (Very Long Instruction Word)
architecture can help ...
- 918
2
votes
How to respond to the two-handed approach to swapping
Ben's answer is great, but allow me to suggest that you don't need to "respond" to the two-handed approach at all: just say when you're explaining the problem in the first place that they ...
- 529
2
votes
Could you recommend books on concurrent programming?
The Well Grounded Java Developer has an excellent section on concurrency. The author claims that very few developers correctly implement concurrency. As ctrl-alt-delor put it: concurrency is easy; ...
- 272
2
votes
Could you recommend books on concurrent programming?
I have no recommendations for the theory part but since you are asking for implementation advice as well, here we go.
If you are looking to use C sharp (you haven't specified a specific language of ...
- 1,884
2
votes
When should concurrency and parallel multi-processing concepts be introduced?
I do not see much value in teaching more than an appreciation of threads and locking, until you have covered less primitive techniques for parallelism.
These techniques allow parallelism that scales ...
- 10.7k
2
votes
When should concurrency and parallel multi-processing concepts be introduced?
In UK at A-level
We cover the following.
Multi-core, semaphores, queues, process pipeline, SISD, MISD, SIMD, MIMD.
We don't specifically cover how to write programs using these. A student could ...
- 10.7k
2
votes
When should concurrency and parallel multi-processing concepts be introduced?
Given the type of software development that occurs these days, such as on mobile phones and with "big data" technologies, I think concurrency, threading, etc. should be introduced very early. ...
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