A Philosophy of Software Design – Book Summary and Notes(elvischidera.com)
elvischidera.com
A Philosophy of Software Design – Book Summary and Notes
https://elvischidera.com/2022-04-29-philosphy-software-design/
36 comments
I didn't know this new edition.
Thank you, now I have one more reason to re-read this book.
It's amazing.
Thanks. I will read this and update the summary. I have updated the book link to point to the second edition.
Thanks for this. I bought and read the first edition last year, and the second edition was published right while I was in the middle of reading it! (Which I didn't discover until a month after I had finished reading.)
One of the reasons I appreciate this book so much, even if I disagree with parts, is the author's humble approach starting with the title, with both "a" and "philosophy". Throughout the content I also felt like he invited me to disagree with him. This made me like it was more of a conversation of trade offs rather than an argument on who is right.
Great notes! I recently read Philosophy of Software Design, but decided not to take notes on it because I wanted to finish it in a reasonable time period.
I'm currently a few chapters into a few other books which I chose to take notes on, but it's very slow going and my desire to read those books has decreased because it feels like a slog.
How do you combat the desire to note every little detail (how do you decide what's important)?
Also, do you take notes directly in a text editor, or do you take handwritten notes and then transcribe them later?
I'm currently a few chapters into a few other books which I chose to take notes on, but it's very slow going and my desire to read those books has decreased because it feels like a slog.
How do you combat the desire to note every little detail (how do you decide what's important)?
Also, do you take notes directly in a text editor, or do you take handwritten notes and then transcribe them later?
https://en.wikipedia.org/wiki/Critical_pr%C3%A9cis
https://www.businessstudynotes.com/personal-skills/precis-wr...
https://www.gutenberg.org/ebooks/53680
Take Notes by hand using Paper/Pen/Pencil, use text, diagrams whatever you need to enhance your comprehension; Transcribe later to Computer, if needed.
https://www.businessstudynotes.com/personal-skills/precis-wr...
https://www.gutenberg.org/ebooks/53680
Take Notes by hand using Paper/Pen/Pencil, use text, diagrams whatever you need to enhance your comprehension; Transcribe later to Computer, if needed.
> How do you combat the desire to note every little detail (how do you decide what's important)?
I try to focus on the general idea of each section in a book.
> Also, do you take notes directly in a text editor
Yes, in markdown.
I try to focus on the general idea of each section in a book.
> Also, do you take notes directly in a text editor
Yes, in markdown.
Not really about your note summaray but neat. I really want to make a digital garden like yours with notes and all. I read plenty of books and articles but I'm helpless when to documenting my findings.
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>Programmers aren’t bound by practical limitations such as laws of physics, they are bound by their limited ability to understand the systems they create.
First line is already wrong. I mean I get the meaning but this is not technically true. Computing is bounded by the laws of physics. We have bottlenecks and limitations everywhere this is entirely due to physics.
It influences even the style of programming. There is much more parallelism in programming today due very much to physical limitations in raw speed.
First line is already wrong. I mean I get the meaning but this is not technically true. Computing is bounded by the laws of physics. We have bottlenecks and limitations everywhere this is entirely due to physics.
It influences even the style of programming. There is much more parallelism in programming today due very much to physical limitations in raw speed.
Other comments have already responded to this. I will just add two excerpts that came to my mind when I read this in the book.
> The constraints imposed in building large software systems are the limitations of the human mind; opposed to the physical systems' constraints in other kinds of engineering.
- MIT 6.001 Structure and Interpretation: https://youtube.com/playlist?list=PLE18841CABEA24090
> The programmer, like the poet, works only slightly removed from pure thought-stuff. He builds castles in the air, from air, creating by exertion of the imagination. Few media of creation are so flexible, so easy to polish and rework, so readily capable of realizing grand conceptual structures. Yet the program construct, unlike the poet's words, is real in the sense that it moves and works, producing visible outputs separate from the construct itself. It prints results, draws pictures, produces sounds, moves arms.
- Mythical man month
> The constraints imposed in building large software systems are the limitations of the human mind; opposed to the physical systems' constraints in other kinds of engineering.
- MIT 6.001 Structure and Interpretation: https://youtube.com/playlist?list=PLE18841CABEA24090
> The programmer, like the poet, works only slightly removed from pure thought-stuff. He builds castles in the air, from air, creating by exertion of the imagination. Few media of creation are so flexible, so easy to polish and rework, so readily capable of realizing grand conceptual structures. Yet the program construct, unlike the poet's words, is real in the sense that it moves and works, producing visible outputs separate from the construct itself. It prints results, draws pictures, produces sounds, moves arms.
- Mythical man month
The parallel with Mythical Man Month resonates with me.
Of course 'executing code' and 'human minds' are bound by physics, that's a relatively uninteresting insight.
The point is: the process of human minds writing software is constrained by the understanding of single human minds. So the 'meta task' of software engineering becomes working around that constraint.
That's why decomposition is such a powerful tool for large software system development because it:
a. reduces the amount of working memory a single mind needs to make a change and
b. lets more human minds work on the solution in parallel without forcing every mind to understand everything about the overall system
Of course 'executing code' and 'human minds' are bound by physics, that's a relatively uninteresting insight.
The point is: the process of human minds writing software is constrained by the understanding of single human minds. So the 'meta task' of software engineering becomes working around that constraint.
That's why decomposition is such a powerful tool for large software system development because it:
a. reduces the amount of working memory a single mind needs to make a change and
b. lets more human minds work on the solution in parallel without forcing every mind to understand everything about the overall system
I don't see how a eloquent quotation proves a point?
Software is bounded by the human mind AND physics. Everything is actually bounded by the previous aforementioned things. It's just that the physical bounds are less apparent for programming. But it is only "less" apparent measured relative to other engineering fields... when viewed without comparison to other engineering fields, the physical limitations of software are still readily apparent.
When you replied to me, was the post created instantaneously or was there a delay? That delay is due to physical limitations. If you don't code taking into account physical limitations and Big Oh complexity, well those limitations become even MORE apparent. In fact the entire Big Oh complexity thing solely exists because of physical limitations.
Software is bounded by the human mind AND physics. Everything is actually bounded by the previous aforementioned things. It's just that the physical bounds are less apparent for programming. But it is only "less" apparent measured relative to other engineering fields... when viewed without comparison to other engineering fields, the physical limitations of software are still readily apparent.
When you replied to me, was the post created instantaneously or was there a delay? That delay is due to physical limitations. If you don't code taking into account physical limitations and Big Oh complexity, well those limitations become even MORE apparent. In fact the entire Big Oh complexity thing solely exists because of physical limitations.
Reread my comment I wasn’t trying to prove a point. I explicitly stated why I included the quotes :)
I wasn’t going to repeat what the other comments already said: you are right but you are missing the point? Like you said:
> But it is only "less" apparent measured relative to other engineering fields... when viewed without comparison to other engineering fields
I don’t think any of the authors will disagree with what you just said.
I wasn’t going to repeat what the other comments already said: you are right but you are missing the point? Like you said:
> But it is only "less" apparent measured relative to other engineering fields... when viewed without comparison to other engineering fields
I don’t think any of the authors will disagree with what you just said.
The Mythical Man Month might be an object of worship but it was written in 1975 at a time when software engineering was VERY different than today. Most of what today's developers do is not close to castles in the air and much more like building generic office blocks on the ground.
Of course, some people have to solve novel problems but 99% of us don't, we just solve the same problems again and again.
Of course, some people have to solve novel problems but 99% of us don't, we just solve the same problems again and again.
A better way to interpret "constraint" in this is as the "limiting factor."
It's that the active constraint is understanding.
I like the book a lot, however one flaw it has is that it provides too few concrete examples to illustrate what it is talking about, and thus often remains in the abstract. You basically already have to have the experience to recognize and remember the situations it’s talking about, and then nod along when your experience matches the author’s.
I'm getting delicious hints of Brooks, Gall, Deming, and Meadows in
this mix. Just reading through the TOC it feels like he's building the
premises for a knock-down argument against code mono-cultures built by
giant teams and delivered JIT on the meanest budget by corrupt
monopolies. But then of course he is.
As Ian Sommerville more or less said it the other day, we've got the philosophies, the textbooks, the smart people, the pragmatism, and the need, so why don't we get to build the quality of software we know in our hearts we can make and deserve? Is what we call "infrastructure" today a stagnation by which Capitalism ultimately eats its own means of innovation?
As Ian Sommerville more or less said it the other day, we've got the philosophies, the textbooks, the smart people, the pragmatism, and the need, so why don't we get to build the quality of software we know in our hearts we can make and deserve? Is what we call "infrastructure" today a stagnation by which Capitalism ultimately eats its own means of innovation?
It is quite extraordinary that such a treatise would not have an entire section on "What is a User?", and really very weird to me that the primacy of the user over the developer, in terms of making the thing useful, is ignored.
The book is about the inner design of software (how you implement your product), not about product design (what the user sees).
The table of Contents seemed interesting and I was getting ready to buy the book until I discovered - the author has reserved between 1/3 and 1/4 of the book for chapters about writing comments.
~1/7 of the book by page count (about 30 pages if you tally the chapter lengths of nearly 200 pages), three chapters of twenty-two are dedicated to that topic (so not even 1/7th of the chapters). That seems reasonable since it's meant to be a broad book regarding software design and development. At least one page on comments is actually an answer to part of Clean Code, which is also relevant as the two books are in, roughly, the same subcategory of books on programming.
> ~1/7 of the book by page count (about 30 pages if you tally the chapter lengths of nearly 200 pages),
Comments chapters start from Page #91 to 142, totals to 52. Total pages - 175; not counting index and summary pages.
1/4 of 175 = 43.75
1/3 of 175 = 58.33
Comments chapters start from Page #91 to 142, totals to 52. Total pages - 175; not counting index and summary pages.
1/4 of 175 = 43.75
1/3 of 175 = 58.33
No, it doesn't. There are three chapters in that span that are on comments, but not all the chapters in that span are on comments. One is on naming things (Ch 14) and one is on modifying existing code (Ch 16). There are three chapters per the TOC that cover comments explicitly (versus where it may be touched on in other chapters): Ch 12 (pages 95-99), Ch 13 (101-120) and Ch 15 (131-135). That's a whopping 30 pages.
You seem to consider it a negative to spend time on comments. Why?
> You seem to consider it a negative to spend time on comments. Why?
Not just me. I've heard, read - here at HN, in the industry, blogs, co-workers, other books - the code should be self-explanatory. If it needs comments to explain then either the code author can't write good code or they are overly complicating it. Besides that, over time, comments get obsolete. We've to fight to get capacity to address tech debt. I don't see that time getting used in refreshing the comments
Not just me. I've heard, read - here at HN, in the industry, blogs, co-workers, other books - the code should be self-explanatory. If it needs comments to explain then either the code author can't write good code or they are overly complicating it. Besides that, over time, comments get obsolete. We've to fight to get capacity to address tech debt. I don't see that time getting used in refreshing the comments
Short vars, long vars. Golfer, extender. Globalist and miniscoper. Class-splitter and method-lumper. Abstract composer and dead-on implementer. Typers, Dicters and Tuplers. I think I've seen them all. But so far I have not worked with a single person who'd not value a well-placed comment.
Can you point me to a codebase that does not use comments, as a model of how that looks in practice?
Can you point me to a codebase that does not use comments, as a model of how that looks in practice?
> Can you point me to a codebase that does not use comments, as a model of how that looks in practice?
Once we actively encourage “comments”, this is what we get. It was totally unnecessary -
https://github.com/nopSolutions/nopCommerce/blob/develop/src...
I welcome this type of comments which does not say the obvious and goes beyond what the code in front of you can’t state -
"// If every heap's gen2 or gen3 size is less than this threshold we will do a blocking GC."
https://raw.githubusercontent.com/dotnet/runtime/main/src/co...
Once we actively encourage “comments”, this is what we get. It was totally unnecessary -
https://github.com/nopSolutions/nopCommerce/blob/develop/src...
I welcome this type of comments which does not say the obvious and goes beyond what the code in front of you can’t state -
"// If every heap's gen2 or gen3 size is less than this threshold we will do a blocking GC."
https://raw.githubusercontent.com/dotnet/runtime/main/src/co...
It’s a vocal but minority opinion, certainly a highly controversial one. As an easy example, it’s pretty difficult for code to self-document why a particular implementation approach was chosen. The book actually addresses the points you note.
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https://web.stanford.edu/~ouster/cgi-bin/book.php