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CodeSOD: Pretty Little State Machine

The Daily WTF
5 days 2 hours ago

State machines are a powerful way to organize code. They are, after all, one of the fundamental models of computation. That's pretty good. A well designed state machine can make a complicated problem clear, and easy to understand.

Chris, on the other hand, found this one.

static { sM.put(tk(NONE, NONE, invite), sp(PENDING, INVITED)); // t1 sM.put(tk(REJECTED, REJECTED, invite), sp(PENDING, INVITED)); // t2 sM.put(tk(PENDING, IGNORED, invite), sp(PENDING, INVITED)); // t3 sM.put(tk(PENDING, INVITED, cancel), sp(NONE, NONE)); // t4 sM.put(tk(PENDING, IGNORED, cancel), sp(NONE, NONE)); // t5 sM.put(tk(PENDING, BLOCKED, cancel), sp(NONE, BLOCKED)); // t6 sM.put(tk(INVITED, PENDING, accept), sp(ACCEPTED, ACCEPTED)); // t7 sM.put(tk(INVITED, PENDING, reject), sp(REJECTED, REJECTED)); // t8 sM.put(tk(INVITED, PENDING, ignore), sp(IGNORED, PENDING)); // t9 sM.put(tk(INVITED, PENDING, block), sp(BLOCKED, PENDING)); // t10 sM.put(tk(ACCEPTED, ACCEPTED, remove), sp(NONE, NONE)); // t11 sM.put(tk(REJECTED, REJECTED, remove), sp(NONE, NONE)); // t12 sM.put(tk(IGNORED, PENDING, remove), sp(NONE, NONE)); // t13 sM.put(tk(PENDING, IGNORED, remove), sp(NONE, NONE)); // t14 sM.put(tk(BLOCKED, PENDING, remove), sp(NONE, NONE)); // t15 sM.put(tk(PENDING, BLOCKED, remove), sp(NONE, BLOCKED)); // t16 sM.put(tk(NONE, BLOCKED, invite), sp(PENDING, BLOCKED)); // t17 sM.put(tk(IGNORED, PENDING, invite), sp(PENDING, INVITED)); // t19 sM.put(tk(INVITED, PENDING, invite), sp(ACCEPTED, ACCEPTED)); // t20 sM.put(tk(NONE, NONE, remove), sp(NONE, NONE)); // t21 sM.put(tk(NONE, BLOCKED, remove), sp(NONE, BLOCKED)); // t22 sM.put(tk(BLOCKED, NONE, remove), sp(NONE, NONE)); // t23 }

Honestly, I only know this is a state machine because Chris told me. I could hazard a guess base on the variable name sM. The comments certainly don't help. Numbering lines isn't exactly what I want comments for. I don't know what tk or sp are actually doing.

So yes, this is an unreadable blob that I don't understand, which is always bad. But do you know what elevates this one step above that? If you note the third parameter to the tk function- invite, cancel, accept, etc? Those are constants. So are INVITED, PENDING, ACCEPTED.

While I am not fond of using the structure of a variable name to denote its role, "caps means const" is a very well accepted standard. A standard that they're using sometimes, but not all the time, and just looking at this makes me grind my teeth.

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Remy Porter

A New Four-Person Crew Will Simulate a Year-Long Mars Mission, NASA Announces

Slashdot
5 days 4 hours ago
Somewhere in Houston, four research volunteers "will soon participate in NASA's year-long simulation of a Mars mission," NASA announced this week, saying it will provide "foundational data to inform human exploration of the Moon, Mars, and beyond." The 378-day simulation will take place inside a 3D-printed, 1,700-square-foot habitat at NASA's Johnson Space Center in Houston — starting on October 19th and continuing until Halloween of 2026: Through a series of Earth-based missions called CHAPEA (Crew Health and Performance Exploration Analog), NASA aims to evaluate certain human health and performance factors ahead of future Mars missions. The crew will undergo realistic resource limitations, equipment failures, communication delays, isolation and confinement, and other stressors, along with simulated high-tempo extravehicular activities. These scenarios allow NASA to make informed trades between risks and interventions for long-duration exploration missions. "As NASA gears up for crewed Artemis missions, CHAPEA and other ground analogs are helping to determine which capabilities could best support future crews in overcoming the human health and performance challenges of living and operating beyond Earth's resources — all before we send humans to Mars," said Sara Whiting, project scientist with NASA's Human Research Program at NASA Johnson. Crew members will carry out scientific research and operational tasks, including simulated Mars walks, growing a vegetable garden, robotic operations, and more. Technologies specifically designed for Mars and deep space exploration will also be tested, including a potable water dispenser and diagnostic medical equipment... This mission, facilitated by NASA's Human Research Program, is the second one-year Mars surface simulation conducted through CHAPEA. The first mission concluded on July 6, 2024.

Read more of this story at Slashdot.

EditorDavid