From: "Guy N. Hurst" <gnhurst@...>
Date: 2001-03-24T18:29:27+09:00
Subject: [ruby-talk:13167] Re: Amusing contrast

Dave Thomas wrote:
> ...
> No, but clarity and conciseness are not competing goals. I
> deliberately wanted to see examples that were of comparable length to
> the original.
> 
> No takers?
> 

Ok, I tried it...  but there were ten lines, not twelve to start.
And we still need a name for this process... 


>   File.foreach($config || "config.status") do |$_|

let's change from the virtual special variable '$_' to 'line'

>     next if /^#/

this is pointless, pitch it

>     if /^s%@(\w+)@%(.*)%g/

not much you can do here - it's a regex after all

>       name = $1
>       val = $2 || ""

In short code, why use this at all?  They are only temp vars anyway

>       next if /^(INSTALL|DEFS|configure_input|srcdir)$/ =~ name

will convert this to remove regex, replace with array method

>       val.gsub!(/\$\{([^{}]+)\}/) { "$(#{$1})" }
>       CONFIG[name] = val

these can be combined since 'val' is only a temp var. Bang is spurious.
Replacing the block would simplify things, too.

>     end
>   end


Result:


File.foreach($config || "config.status") do |line| 
	if line =~ /^s%@(\w+)@%(.*)%g/
		unless %w(INSTALL DEFS configure_input srcdir).include? $1
			CONFIG[$1] = ($2||"").gsub(/\$\{([^{}]+)\}/, '$(\1)' )
		end
	end
end


If you don't like line 4, using $1 and $2, or you wish to
relocate as much character noise as possible, you may wish to 
do the following:


config_file = $config || "config.status"
line_regex = /^s%@(\w+)@%(.*)%g/	# two match results
val_regex = /\$\{([^{}]+)\}/ 		# one match result

File.foreach(config_file) { |line|
	if match_result = line_regex.match(line)
		name, val = match_result[1], (match_result[2] || "")  # prevent nil for gsub
		unless %w(INSTALL DEFS configure_input srcdir).include? name
			CONFIG[name] = val.gsub(val_regex,'$(\1)')   # \1 is the match
		end
	end
}



Guy N. Hurst


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