I know where I am but not how I got here

i_am_puts_debugger_1.md

I know where I am but not how I got here

By @tenderlove. Full post I am puts debugger

Sometimes I’ll be debugging an issue and know where the problem is, but not how I got there. For those times I’ll just do puts caller to get the callstack.

For example I have this code:

LOOKUP = Hash.new { |h, k| h[k] = Type.new(k) unless k.blank? }

But I need to know how the default block is getting called, I do this:

  LOOKUP = Hash.new { |h, k|
    puts "#" * 90
    puts caller
    puts "#" * 90
    h[k] = Type.new(k) unless k.blank?
  }

The above code will print out 90 hash tags, then the call stack, then 90 more hash tags. I print out the hash tags so that if it gets called multiple times, I can easily differentiate the call stacks. If I only want to print the call stack once, just use exit! after printing the callstack, or call raise. raise will show an exception so you see the stack anyway.

I only want to see the stack in certain cases

This is debugging code, so you can do whatever you want. Lets say I just want to see the stack when adding something to the hash. Just do this:

  LOOKUP           = Hash.new { |h, k|
    unless k.blank?
      puts "#" * 90
      puts caller
      puts "#" * 90
      h[k] = Type.new(k)
    end
  }

Since I’m going to throw this code away anyway, I’m free to add any kind of weird conditionals I’d like!