Use embedded string as variable name

Question

I have a YAML file that uses the encoding __firstname__ as a placeholder which signifies that an existing method firstname should be used, rather than the literal string in a subsequent process.

I am trying to understand the most ruby way to to do this. Basically, I need to extract the part between the underscores and send it to an object. Here is pseudocode:

variable = '__firstname__'
if variable is prefixed and suffixed with underscores
   result = object.send(variable.removeunderscores)
else
   result = variable
end

puts result

I was about to write this procedurally like this, but this is the type of thing that I think ruby can less clunkily if only I knew the language better.

What is a clean why to write this?

Maybe something like: result = variable.gsub!(/\A_|_\Z/, '')) ? object.send(variable) : variable? It's destructive and honestly not that elegant, but it is a one-liner if that's your kind of thing. Personally, I think your approach is plenty clean for what you're trying to do. — Jon Egeland
– Jon Egeland, Commented Feb 20, 2015 at 3:10
And actually, that one-liner isn't entirely correct. Sometimes having longer code is nice just to make sure you're doing things properly. Performance-wise, your current solution and that one-liner are pretty similar anyway. — Jon Egeland
– Jon Egeland, Commented Feb 20, 2015 at 3:11

Anthony · Accepted Answer · 2015-02-20 03:45:37Z

1

There's nothing wrong with verbose code if it's clear to read IMO.

I'd do something like this using String#start_with? and String#end_with?:

variable = '__firstname__'
if variable.start_with?("__") && variable.end_with?("__")
   result = object.send(variable[2...-2])
else
   result = variable
end

edited Feb 20, 2015 at 3:45

answered Feb 20, 2015 at 3:33

Anthony

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