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Comment Re:What about the alternative virtual coins ? (Score 1) 275 275

A bitcoin is a unit of measurement. It's no more meaningful to ask what a bitcoin looks like than to ask what a centimeter (or an inch) looks like.

The global shared ledger of the Bitcoin system, the "block chain", holds transactions. Each transaction contains inputs and outputs. All inputs must be valid outputs of a previous transaction. Inputs and outputs have a size specified in bitcoins (with the base unit being 0.00000001 bitcoin, also known as a "satoshi"). All outputs are labelled with a bitcoin receiving address, which is the hash of a public key. The receiving address was generated by the holder of the corresponding private key, who can spend the corresponding output as the input to a new transaction.

A miner collects unprocessed transactions and attempts to get them accepted into the block chain. By consensus (enforced through software), each block is accepted if accompanied by a valid hash whose value is less than a certain limit. Miners compete against each other to be first to find a suitable hash for a new block, because each block is allowed to include a reward for the miner. The reward is a freshly minted output.

The consensus (enforced through software) is that the block reward halves approximately every 4 years, such that the total bitcoins issued will asymptotically approach a fixed maximum of 21 million. Currently the reward is 25 bitcoins per block.

The threshold for a valid hash adjusts approximately every 10 days to ensure that new blocks are produced approximately every ten minutes. This is expressed as the "difficulty factor", and will rise as more hashing power joins the network.

Comment Re:That brings back memories... (Score 3, Interesting) 129 129

It's tough to describe how space-age that stuff was in the 1980s

They were amazing times. I remember having my mind blown by a demonstration of the Apple Lisa in 1983.

In this video, when they show the Paint program, listen to the gasps of wondrous amazement when the "eraser" tool is demonstrated.

Comment You can start people clapping really easily (Score 5, Interesting) 138 138

When I was in my teens, I was watching a circus. Between every act, a cleaner with a broom and a garbage bag would clear any detritus from the ring.

After a few acts, I clapped this guy, just for a laugh. To my surprise, everyone else joined in. From that point on, until the end of the show, the cleaner got rapturous applause every time!

Comment The first online appliance that non-geeks discover (Score 1) 236 236

This product is significant because it will be the first online appliance that most non-geeks will discover.

After people get used to the Good Night Lamp, they won't bat an eyelid when their car tweets that it has just received a parking ticket (and by the way, the front left tire is half-flat). They'll take it in good stride when their refrigerator emails to say that it is shutting down unless the six-month-old lump of rotting blue cheese is removed by midnight.

People will expect their toothpaste tube to order the next tube to be delivered just in time, and won't be surprised if the park bench posts a YouTube video of their fat ass sitting on it.

Comment Re:Agree complete (Score 1) 231 231

Parliament can and should come out and say "Many years ago, our country adopted laws and policies which we now know were morally wrong. We apologize for those acts. We cannot undo all of the wrong that was done, but this is what we are doing: repealing all laws against victimless crimes, and releasing everyone currently imprisoned for victimless crimes

Fixed it for you!

Comment There is a better way to use exceptions (Score 2) 536 536


The key to taming exceptions is to use them differently. Any exception that escapes a method means that the method has failed to meet its specification, and therefore you will need to clean up and abort at some level in the call chain. But you don't need to catch at every level (unless your language forces you to), nor should you need to do anything that relies on the "meaning" of the exception. Instead, you take a local action: close a file, roll back the database, prompt the user to save or abandon, etc, and either re-throw or not according to whether you have restored normality. There will only be a few places in your app where this type of cleanup is needed.

If you're not doing it this way, you're using exceptions as a control structure, and that's never going to be clean.
