Decremental Development @KevlinHenney Your customers do not buy - PowerPoint PPT Presentation

Decremental Development @KevlinHenney

Your customers do not buy your software by the line. David Evans

Remember that there is no code faster than no code. Taligent's Guide to Designing Programs

Remember that there is no code cheaper to maintain than no code.

Remember that there is no code more secure than no code.

https://twitter.com/KevlinHenney/status/538296211166740480

I have made this [letter] longer than usual because I have not had time to make it shorter. Blaise Pascal

Je n'ai fait celle-ci plus longue que parce que je n'ai pas eu le loisir de la faire plus courte. Blaise Pascal

I have made this [letter] longer than usual because I have not had time to make it shorter. Blaise Pascal

time

I spent a lot of money on booze, birds and fast cars. The rest I just squandered. George Best

speed

velocity

v = v x + v y

v = | v |

v = s _ t

s t

s t

s [T] [T] t

utilisation

quality of estimation

Orient Observe Understand where Gather information from a range of you're at and where sources you want to be Act Decide Carry out the plan Develop a plan for action Boyd's OODA Loop

Act Decide Carry out the plan Develop a plan for action Orient Observe Understand where Gather information you're at and where from a range of sources you want to be Boyd's OODA Loop

Do Plan Carry out the plan Establish hypothesis, goal or work tasks Act Study Revise approach Review what has or artefacts based been done against plan (a.k.a. Check ) on study Deming/Shewhart Cycle

The design process is an iterative one. Andy Kinslow

A software system can best be designed if the testing is interlaced with the designing instead of being used after the design. Alan Perlis

Do Plan Carry out the plan Establish hypothesis, goal or work tasks Act Study Revise approach Review what has or artefacts based been done against plan (a.k.a. Check ) on study Deming/Shewhart Cycle

Reify Write Implement so that Create or extend a test case for new the test passes behaviour — as it's new, the test fails Refactor Reflect Make it so! Is there something in the code or tests that could be improved? Test-First Cycle

Why do cars have brakes?

Cars have brakes so you can slow down.

Cars have brakes so you can go fast.

http://www.commitstrip.com/en/2016/08/25/a-very-comprehensive-and-precise-spec/

http://www.commitstrip.com/en/2016/08/25/a-very-comprehensive-and-precise-spec/

http://www.commitstrip.com/en/2016/08/25/a-very-comprehensive-and-precise-spec/

http://www.commitstrip.com/en/2016/08/25/a-very-comprehensive-and-precise-spec/

code tests scripts

codified knowledge

knowledge acquisition

knowledge retention

learning

communication

social negotiation

model of participation

The biggest advantage of autonomously working teams is risk reduction through increased group intelligence. Kevlin Henney https://jaxlondon.com/blog/java-core-languages/the-error-of-our-ways-kevlin-henney/

There’s little correlation between a group’s collective intelligence and the IQs of its individual members. But if a group includes more women, its collective intelligence rises. "What Makes a Team Smarter? More Women" Anita Woolley & Thomas W Malone http://hbr.org/2011/06/defend-your-research-what-makes-a-team-smarter-more-women/

The four conditions that characterize wise crowds: diversity of opinion, independence, decentralization, and aggregation.

size

scale

The first rule of scaling agile is… don't do it! Or rather, try to avoid it for as long as you possibly can. Andreas Rowell First Rule of Scaling Agile – DON'T! https://www.linkedin.com/pulse/first-rule-scaling-agile-dont-andreas-rowell/

Software development does not have economies of scale. Development has diseconomies of scale. Allan Kelly Beyond Projects http://www.slideshare.net/allankellynet/no-prokects-beyond-projects-refreshed-version

𝑢 = 𝑢 1 completion time for one person

𝑢 = 𝑢 1 𝑜 division of labour

𝑜 − 1 Amdahl's law 𝑢 = 𝑢 1 1 − 𝑞 𝑜 portion in parallel

𝑜 − 1 + 𝑙 𝑜 𝑜 − 1 𝑢 = 𝑢 1 1 − 𝑞 𝑜 2 connections (worst case) communication overhead (typical)

𝑜 − 1 + 𝑙 𝑜 𝑜 − 1 𝑢 = 𝑢 1 1 − 𝑞 𝑜 2 t n

http://boingboing.net/2016/04/05/man-recreates-tsas-47400.html

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I have yet to see any problem, however complicated, which, when you looked at it in the right way, did not become still more complicated. Anderson's Law

The Facebook iOS app has over 18,000 Objective-C classes, and in a single week 429 people contributing to it. Facebook's code quality problem Graham King http://www.darkcoding.net/software/facebooks-code-quality-problem/

For every activity there is a certain appropriate scale.

Th The e bas asic ic thesis hesis [.. ...] .] is that hat organiza ganization tions s whi hich h design esign syst stems ems [.. ...] .] ar are e constrain nstrained ed to o pr produce oduce designs esigns whi hich h ar are e copie pies s of the he communic municati ation on structu ructures res of the hese se organiza ganization tions. s. Melvin vin Conw nway How Do Committees Invent?

We e ha have e seen een tha hat t this his fac act t ha has importan portant t implicatio plications ns for or the he man anag ageme ement nt of syst stem em design. esign. [.. ...] .] A design esign ef effo fort rt should hould be e organize ganized d ac accord ording ing to the he ne need ed for or communicatio munication. n. Melvin vin Conw nway How Do Committees Invent?

In referring to this as a ‘law,’ the appeal is to a force that will shape a system, much as a physical law, rather than as a rule that should be followed, as with the laws of a community or a state.

In this sense it is not a law that can be broken — the force is always there — only one that can be counterbalanced by other forces.

thrust lift gravity drag

design practice conway debt

We may therefore picture the process of form- making as the action of a series of subsystems, all interlinked, yet sufficiently free of one another to adjust independently in a feasible amount of time. It works, because the cycles of correction and recorrection, which occur during adaptation, are restricted to one subsystem at a time. Christopher Alexander Notes on the Synthesis of Form

https://twitter.com/kcpeppe/status/15473004648

Remove to improve