How can use a variable in the name of another variable? Say, I have a number of arrays like this:
g_OS = ['Mac', 'Linux', 'Win']
g_Mac = ['Lion', 'Tiger', 'Jaguar']
g_Linux = ['Slackware', 'RedHat', 'Caldera']
g_Win = [ .... ]
If I do this: g_OS.each {|OS| puts "g_#{OS}[0]"}, it will print 'g_Mac[0]' or 'g_Linux' as a literal string. But what I actually want is to get the first element of the array: g_Mac. How can I do that?
Generally it's easier just to rearrange your data. Like this, for example.
g_OS = {
'Mac' => ['Lion', 'Tiger', 'Jaguar'],
'Linux' => ['Slackware', 'RedHat', 'Caldera'],
'Win' => ['Chicago', 'Daytona', 'Longhorn']
}
# list just the OSes
g_OS.keys # => ["Mac", "Linux", "Win"]
# only linuxes
g_OS['Linux'] # => ["Slackware", "RedHat", "Caldera"]
Although it's technically possible to do exactly what you asked, I advise you against it (and will not, therefore, post the code). You seem to be new, so you have lots to learn. Don't learn wrong ways.
g_OS in this example) is generated dynamically from a file and so the others as well. Arranging the data the way you suggested probably make it a bit complicated for an ERB template(??). On a separate note, do you mind explaining what wrong with my original approach please?Slackware, Linux, i-num=1 || Jaguar, Macx, i-num=6 || Chicago, that_Win, i-num=2 || Daytona, this_Win, i-num=7 || RedHat, Linux, i-num=5 || Tiger, Macy, i-num=3 (|| are the line breaks, of course.) Cheers!!
This is to answer to my own question, which completely different compare to my original question, but it serves exactly (well, more or less) the same purpose. So, as Sergio suggested: Say the example input file is something like this:
maci:ruby san$ cat OSs.txt
Slackware, Linux, i-num=1
Jaguar, MacX, i-num=6
Chicago, this_Win, i-num=2
Daytona, an_other_Win, i-num=7
RedHat, Linux, i-num=5
Lion, MacY, i-num=4
Caldera, Linux, i-num=9
Longhorn, that_Win, i-num=8
Tiger, MacZ, i-num=3
Indiana, Solaris, i-num=10
Kodiak, MacX, i-num=11
The actual file is dynamically created with variable number of OSs i.e. the file may or may not have Mac or Win at all. Taking from there, this is what I came up so far....
inFile = "OSs.txt"
os = {}
open(inFile, 'r').each do |line|
next if line =~ /^\s*(#|$)/
if line.split(',').map(&:strip)[1] =~ /^Mac/
(os[:Mac] ||= []) << line.split(',').map(&:strip)[0]
end
if line.split(',').map(&:strip)[1] =~ /_Win$/
(os[:Win] ||= []) << line.split(',').map(&:strip)[0]
end
if line.split(',').map(&:strip)[1] !~ /(^Mac|_Win$)/
(os[:Linux] ||= []) << line.split(',').map(&:strip)[0]
end
end
os.each_key do |cls|
p "%s [%s]" % [os[cls][0], os[cls].count]
end
It's pretty much doing what I actually want but I believe there are a lot better ways of doing it. Cheers!!