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Comment by stackbutterflow | Hacker News Reader

I find regex easier to write than to read.

I never copy them from stackoverflow because I'm worried it does some weird magic that I don't want. Instead I build them against one or more examples.

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> I find regex easier to write than to read.

There is nothing new under the sun.

Joel, 22 years ago:

There’s a subtle reason that programmers always want to throw away the code and start over. The reason is that they think the old code is a mess. [...] The reason that they think the old code is a mess is because of a cardinal, fundamental law of programming: It’s harder to read code than to write it.

https://www.joelonsoftware.com/2000/04/06/things-you-should-...

I say that because there's a meme that nobody writes regex and that everyone copy-paste it from stackoverflow.

And the corollary: since code is harder to read than write, steer clear of writing clever code where simple code would suffice, as the clever code will be much harder to read.

A second argument is that debugging is harder than writing.

s/writing/reading

AKA Kernighan's Law: https://www.laws-of-software.com/laws/kernighan/

Joel is 100% spot on. This is exactly why I don’t think things like Copilot will catch on. Making programming involve less writing code and more reading code actually makes the job more difficult.

I can highly recommend regexr.com for testing and developing regex patterns; paste a representative sample in the "Text" area and it'll show you how things match (and usually, crucially, don't match) as you change the regex pattern.

I'm not associated with them, and I understand you don't seem to have any real issues with regex, but thought this would be a good place to mention a useful tool.

Nice! I’ve been writing (and reading) regexes for over 20 years now. I can usually ‘read’ them on sight, but I’ve been wanting this tool for when it all goes wrong.

Which of course always happens at least once or twice in any new dataset/usage.

I've used that and regexbuddy and others over the years. Almost anything the gives you some visual rendering of what's going on is helpful. Personally, I've taken to using the regex stuff in the Jetbrains IDEs, mostly because I'm there already most of the time, and it's 'good enough'. But I'm not always at my own setup, and regexr and similar are always a good tool to have (and to share with others to show them how a regex is working).

If I did this all the time, I might not need tools like this. But complex regex are something I only dive in to a handful of times per year, and it's never the same problem twice.

Using such testing you can only prove a regex isn’t what you want for specific inputs, and make a number of plausibility checks, but you can’t prove it is what you want for all inputs. For that you need to do the reasoning on the expression as if you had built it yourself.

Thanks for pointing out regexr.com.

I really appreciate the availability of tools like that.

See also the Emacs built-in M-x re-builder (for elisp-style regexp).

Totally agree! But oddly enough, I have this problem with all code/languages… I always write code much more easily than I read it. I can write fairly complex applications just by following the logic of what the application must do in my brain (but with ZERO cleverness). But give me the source code of even the simplest Unix command and I’ll struggle to understand the purpose of every #define, the variable naming scheme, etc., etc. I’m sure this is telling me something interesting about how my brain works but I’m not sure what!

> I’m sure this is telling me something interesting about how my brain works

See my sibling comment. Joel says you are just normal.

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