Consider the following snippet:
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#!/usr/bin/ruby
class Thing
def initialize(name) @name = name end
def to_s @name end
def to_i @name.length end end
a = Bla.new("foo")
printf "%s\n", a printf "%d\n", a printf "%c\n", a
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This code breaks at the last line with the message :
./go7:22:in `printf': can't convert Thing into Integer (TypeError)
It seems that the printf conversion to %c tries to call a specific method of my class to convert the object to the appropriate format. I am a bit confused about the message "can't convert to integer", since the to_i method is defined, and sucessfully called that the printf "%d" line.
So, two questions arise
- what method am I supposed to provied for printf so it can handle the '%s' format string
- How can I figure this out myself. It seems that printf is trying to call something, but I have no way of telling exactly *what* it is trying to do. Is there some kind of tracing/debugging that can be switched on to see what's printf is trying to do ?
Thank you very much,