Read a configuration file

Read a configuration file is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

The task is to read a configuration file in standard configuration file, and set variables accordingly. For this task, we have a configuration file as follows:

# This is a configuration file in standard configuration file format
#
# Lines begininning with a hash or a semicolon are ignored by the application
# program. Blank lines are also ignored by the application program.

# This is the fullname parameter
FULLNAME Foo Barber

# This is a favourite fruit
FAVOURITEFRUIT banana

# This is a boolean that should be set
NEEDSPEELING

# This boolean is commented out
; SEEDSREMOVED

# Configuration option names are not case sensitive, but configuration parameter
# data is case sensitive and may be preserved by the application program.

# An optional equals sign can be used to separate configuration parameter data
# from the option name. This is dropped by the parser. 

# A configuration option may take multiple parameters separated by commas.
# Leading and trailing whitespace around parameter names and parameter data fields
# are ignored by the application program.

OTHERFAMILY Rhu Barber, Harry Barber

For the task we need to set four variables according to the configuration entries as follows:

• fullname = Foo Barber
• favouritefruit = banana
• needspeeling = true
• seedsremoved = false

We also have an option that contains multiple parameters. These may be stored in an array.

• othernames(1) = Rhu Barber
• othernames(2) = Harry Barber

D

<lang d>import std.stdio, std.getopt, std.string, std.conv, std.regexp ;

template VarName(alias Var) { enum VarName = Var.stringof.toupper ; }

void setOpt(alias Var)(const string line) {

   auto m = RegExp(`^`~VarName!Var~`(\s+(.*))?`).match(line) ;
   if(m.length > 0) {
       static if (is(typeof(Var) == string))
           Var = m.length > 2 ? m[2] : "" ;
       static if (is(typeof(Var) == bool))
           Var = true ;
       static if (is(typeof(Var) == int))
           Var = m.length > 2 ? to!int(m[2]) : 0 ;
   }

}

void main(string[] args) {

   string fullname, favouritefruit ;
   bool needspeeling, seedsremoved ; // default false ;
   int count ; // a line of "COUNT 5" added at end of config file
   foreach(line ; File("readcfg.txt").byLine) {
       auto opt = chomp(text(line)) ;
       setOpt!fullname(opt) ;
       setOpt!favouritefruit(opt) ;
       setOpt!needspeeling(opt) ;
       setOpt!seedsremoved(opt) ;
       setOpt!count(opt) ;
   }
   writefln("%14s = %s", VarName!fullname, fullname) ;
   writefln("%14s = %s", VarName!favouritefruit, favouritefruit) ;
   writefln("%14s = %s", VarName!needspeeling, needspeeling) ;
   writefln("%14s = %s", VarName!seedsremoved, seedsremoved) ;
   writefln("%14s = %s", VarName!count, count) ;

}</lang>

J

<lang j>require'regex' set=:4 :'(x)=:y'

cfgString=:4 :0

 y set 
 (1;&,~'(?i:',y,')\s*(.*)') y&set rxapply x

)

cfgBoolean=:4 :0

 y set 0
 (1;&,~'(?i:',y,')\s*(.*)') y&set rxapply x
 if.-.0-:y do.y set 1 end.

)

taskCfg=:3 :0

 cfg=: ('[#;].*';) rxrplc 1!:1<y
 cfg cfgString 'fullname'
 cfg cfgString 'favouritefruit'
 cfg cfgBoolean 'needspeeling'
 cfg cfgBoolean 'seedsremoved'
 i.0 0

)</lang>

Example use:

<lang j> taskCfg 'fruit.conf'

  (,' = ',]&.do)&>;: 'fullname favouritefruit needspeeling seedsremoved'

fullname = Foo Barber favouritefruit = banana needspeeling = 1 seedsremoved = 0 </lang>

Ruby

<lang ruby>fullname = favouritefruit = needspeeling = seedsremoved = false

open("fruit.conf", "r") do |file|

 file.each_line do |line|
   line.chomp!
   key, value = line.split(nil, 2)
   case key
   when /^([#;]|$)/; # ignore line
   when "FULLNAME"; fullname = value
   when "FAVOURITEFRUIT"; favouritefruit = value
   when "NEEDSPEELING"; needspeeling = true
   when "SEEDSREMOVED"; seedsremoved = true
   when /^./; puts "#{key}: unknown key"
   end
 end

end

puts "fullname = #{fullname}" puts "favouritefruit = #{favouritefruit}" puts "needspeeling = #{needspeeling}" puts "seedsremoved = #{seedsremoved}"</lang>