Update README.md to show multiple commands execution using binding.b

[binarygit]

Description

Describe your changes:
This addition to the README.md demonstrates how to specify multiple commands to run when using binding.b.

I didn't think it obvious that you needed to have two semicolons separating the commands (cmd 1 ;; cmd 2). The README does not document this which is why I thought I would add it there.

I've also added an example to demonstrate how you could use pre and do arguments together to create a more advanced/useful workflow.

P.S. I wouldn't have known how to do both of the above things if it hadn't been for @st0012 Ruby Kaigi talk on debugging. So Thank You for that!

[ko1]

;; is temporary syntax and I'm not sure we should continue to maintain it.
This is why I didn't documented it.

For the pre:, do: command, I think "\n" (newline) is better.

[ko1]

I'm not sure why this added block is needed.

[binarygit]

It wasn't very obvious to me, how I would achieve something like this. I think the technique used is handy in alot of situations but as I said, it wasn't obvious how I would go about doing it. So, I think it's useful to have this documented here.

I would have never thought that

binding.b do: 'watch @a ;; break foo pre: info'

the pre inside the string above would be evaluated correctly, like an argument to a binding.b and thus suspend the program. I would have never thought this would work, so I think it's worth documenting.

But If I missed something in the README that does suggest that this is possible and I missed it, please let me know 😄

[ko1]

I'm curious why it is not clear without explanation. do: accepts debug command string (described) and break foo pre: info is debug command.

BTW, on this case,

debuggerdo: 'watch @a'debuggerdo: 'break foo pre: info'# ordebuggerdo: <<~DO watch @a break foo pre: infoDO

is more readable for me.
(I usually use ;; for writability/easy to write, though)

[binarygit]

Ah! I went through the docs again and see clearly that you have it there.
Sorry, I should have been more thorough!

I will remove the block from my PR.

[binarygit]

I updated my PR removing the above block and I added a sentence about how users can use ;; instead of \n.
I think this will do, no?
Let me know if you want me to add something else.

Also hope ;; stays around 😄

[ko1]

But it is already documented...

RUBY_DEBUG_COMMANDS (commands): debug commands invoked at first stop. commands should be separated by ';;'

So I can accept to describe about it (first part of this patch)

[binarygit]

;; is temporary syntax and I'm not sure we should continue to maintain it.
This is why I didn't documented it.
For the pre:, do: command, I think "\n" (newline) is better.

if the ;; syntax is temporary, and you recommend using the "\n" to separate the commands then I will change the example to use "\n". Also a little info about ;; being temporary might help other people who use it to adopt "\n", wdy think?

[st0012]

But it is already documented...

IMO, it's not very clear that RUBY_DEBUG_COMMANDS and binding.b(do: "cmd") are the same thing. So it's worth mentioning this again in the binding.b API section.

For the pre:, do: command, I think "\n" (newline) is better.

I assume we can still write multiple commands in the same line? Like binding.b(do: "catch StandardError \n i \n bt 10")

[ko1]

if the ;; syntax is temporary, and you recommend using the "\n" to separate the commands then I will change the example to use "\n". Also a little info about ;; being temporary might help other people who use it to adopt "\n", wdy think?

+1

I assume we can still write multiple commands in the same line?

Yes, but not sure it is readable.

[st0012]

I think this feature has 2 types of usages:

1. Quickly replicate a debugging script (copy the line of script and paste it in other places)
   • For example, I sometimes put multiple debugger(do: "i ;; bt 10") as an advanced puts-debugging.
2. Record and share debugging flow with others

For 2), I think newline separator does help:

debuggerdo: <<~DO watch @a break foo pre: infoDO

But it's not convenient for 1) as we now need to copy and paste multiple lines instead of just one. Typing \n for inline usage could work but it's still more difficult to type than ;;. If we want to move away from ;;, I hope it'd be something easier to type than \n.

Another thing to consider is that \n still don't allow multi-level commands as mentioned in #620, which I think should be included in this discussion as well.

[binarygit]

I agree with @st0012\n is more difficult to type than ;;. If there's a way we can keep ;;, I would vote for it!