From: Nathaniel Talbott <ntalbott@...>
Date: 2000-12-29T01:25:27+09:00
Subject: [ruby-talk:8178] Inexplicable core dump

I have some code that looks like this:

14	def update(channel, value=nil)
15		@channels[channel].each {
16			| key, proc |
17			if (proc.arity == 0)
18				proc.call
19			else
20				proc.call(value)
21			end
22		} if ( ! @channels[channel].nil? )
23	end

The first time it gets called in my code where proc.arity != 0 (i.e. it goes
into the else branch) it does one of these:

	./Tuner.rb:20: [BUG] Segmentation fault
	ruby 1.6.2 (2000-12-25) [i686-cygwin]
	      0 [sig] ruby 120 stackdump: Dumping stack trace to ruby.exe.stackdump
	Aborted (core dumped)

OK, I thought maybe there was a bug in my version of Ruby (I didn't have the
stable version of 1.6.2 initially), so I recompiled. Still core dumped. So,
next I figured maybe my code was fruity, so I added an extra check to my
code:

14	def update(channel, value=nil)
15		@channels[channel].each {
16			| key, proc |
17			if (proc.arity == 0)
18				proc.call
19			else if ( proc.arity == 1 || proc.arity == -1 )
20				proc.call(value)
21			else
22				puts("Bad arity: #{proc.arity}")
23			end
24		} if ( ! @channels[channel].nil? )
25	end

The code now ran flawlessly, but the puts wasn't being called! In other
words, the same code was being run, but it wasn't core dumping anymore. So,
I started fiddling with things to see what would and wouldn't run. I
eventually came to find out that this ran great:

14	def update(channel, value=nil)
15		@channels[channel].each {
16			| key, proc |
17			if (proc.arity == 0)
18				proc.call
19			else
20				proc.call(value)
21
22			end
23		} if ( ! @channels[channel].nil? )
24	end

Which is exactly what I started with plus a blank line at 21! I'm completely
clueless. If I remove that blank line, things still core dump. Anybody have
any idea what this is or how to fix it? Let me know if there's any more info
that would be helpful (version info is in the core dump above; I'm running
Windows 2000).

TIA,


Nathaniel

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