Ruby: to_s vs inspect
Published in
1 min readMar 9, 2018
puts and interpolation
The putsmethod implicitly calls the to_s method of the object passed as parameter (except for a String)
class Factory
def initialize
@workers = { workers: [] }
@machines = { machines: [] }
end def add_worker(name)
@workers[:workers] << { :name => name }
end
def add_machines(id)
@machines[:machines] << { :id => id }
end
def to_s
ws = @workers[:workers].map { |w| w[:name] }.join(', ')
ms = @machines[:machines].map { |m| m[:id] }.join(', ')
<<-EOF
Worker Names[#{@workers[:workers].count}]: #{ws}
Machine IDs[#{@machines[:machines].count}]: #{ms}
EOF
end
endfactory = Factory.new
factory.add_worker('Jim')
factory.add_worker('Larry')
factory.add_worker('Doug')
factory.add_machines('12QC-2323')
factory.add_machines('12QC-2324')
factory.add_machines('12QC-2325')
So, a call to puts with factory as parameter will implicitly call factory.to_s
> puts factory
Worker Names[3]: Jim, Larry, Doug
Machine IDs[3]: 12QC-2323, 12QC-2324, 12QC-2325to_s is also implicitly called during String interpolation
> "#{factory}"
" Worker Names[3]: Jim, Larry, Doug\n Machine IDs[3]: 12QC-2323, 12QC-2324, 12QC-2325\n"inspect
The inspect method returns a String that represents the calling object
[1,2,3].inspect # "[1,2,3]"It’s also implicitly called by the p method
p [1,2,3] # "[1,2,3]"Conclusion
to_s is usually used for logging purposes.
inspect is usually used for debugging purposes.
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