Ruby NoMethodError exception calls #inspect by default

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I have found a weird problem in Ruby and I'm not quite sure if it is an issue or it's a feature introduced in recent Ruby versions.

Basically when we call an undefined method, we get an undefined method error as expected in Ruby. The issue is that it also calls inspect and prints out the object and all of its attributes/values. If my object is a complex one, it takes really long time to finish printing everything out and in many times it causes my local rails server to hang, especially when there is an attribute holding binary data. This issue does not seem to happen with Ruby 2.6 but Ruby >= 2.7.

For simple objects, that's not a problem but I'm specifically having the issue with this gem: puppeteer-ruby. Each object in this gem has lots of attributes and dependencies.

Here is an example, I run the following code in IRB with different Ruby version and getting different exceptions:

require 'puppeteer-ruby'
browser = Puppeteer.launch(headless: true)
browser.foo

Ruby 2.6.6

NoMethodError: undefined method `foo' for #<Puppeteer::Browser:0x00007fce2d553b30>
Did you mean?  for

Ruby 3.0.0

(irb):9:in `<main>': undefined method `foo' for #<Puppeteer::Browser:0x00007f9300550740 @ignore_https_errors=false, @default_viewport=#<Puppeteer::Viewport:0x00007f92ffbf8e90 @width=800, @height=600, @device_scale_factor=1.0, @is_mobile=false, @has_touch=false, @is_landscape=false>, @process=#<Puppeteer::BrowserRunner::BrowserProcess:0x00007f92fc5ae448 @spawnargs=["/Applications/Google Chrome.app/Contents/MacOS/Google Chrome", "--disable-background-networking", "--enable-features=NetworkService,NetworkServiceInProcess", "--disable-background-timer-throttling", "--disable-backgrounding-occluded-windows", "--disable-breakpad", "--disable-client-side-phishing-detection", "--disable-component-extensions-with-background-pages", "--disable-default-apps", "--disable-dev-shm-usage", "--disable-extensions", "--disable-features=Translate", "--disable-hang-monitor", "--disable-ipc-flooding-protection", "--disable-popup-blocking", "--disable-prompt-on-repost", "--disable-renderer-backgrounding", "--disable-sync", "--force-color-profile=srgb", "--metrics-recording-only", "--no-first-run", "--enable-automation", "--password-store=basic", "--use-mock-keychain", "--enable-blink-features=IdleDetection", "--headless", "--hide-scrollbars", "--mute-audio", "about:blank", "--remote-debugging-port=0", "--user-data-dir=/var/folders/qn/kx4kb8xx5x13gx77yy2q56fr0000gn/T/puppeteer_dev_chrome_profile-20210910-25051-m7mnxb"], @stdout=#<IO:fd 24>, @stderr=#<IO:fd 26>,......very long text after this..
puppeteer ruby
1 Answers

Thats interesting - inspect has always printed internal variables.

In the blame the last change to inspect was 9 years ago: rb_object_inspect#704

A simple script using 2.6:

> docker run -it ruby:2.6.6-alpine sh
#> ruby -v
ruby 2.6.6p146 (2020-03-31 revision 67876) [x86_64-linux-musl]
#> irb
irb(main):001:0> class Foo; def initialize(message); @message = message; end; end
=> :initialize
irb(main):002:0> Foo.new('hello').foo
NoMethodError (undefined method `foo' for #<Foo:0x00007f35e20e0280 @message="hello">)
Did you mean?  for

Though looking at the source for Puppeteer::Browser it seems they changed to a pure ruby implementation of the browser around 2 years ago. When they did that they introduced a lot of ivars to the class. Perhaps the version you're using changed between updating ruby from 2.6 to 3.0?

A simple fix would be to monkey patch inspect on Puppeteer::Browser, or send a PR to the maintainer - looks like the project is active on GitHub.

roo_7160
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