Class: Usage

Inherits:
Object
  • Object
show all
Defined in:
lib/Usage.rb

Overview

This is the main interface to this usage functionality. It operates by using method_missing to extract information about the command line arguments. Most all the functionality is implemented in the UsageMod::Base class with the Usage class being a wrapper around it to handle errors in a nice graceful fashion.

The main way to use it is to give the usage string as the argument to build the usage object like below:

usage = Usage.new “input_file output_file”

see the README for a more complete description of what can appear in that string.

Instance Method Summary collapse

Constructor Details

#initialize(*args, &block) ⇒ Usage

usage string as well.



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# File 'lib/Usage.rb', line 976

def initialize(*args, &block)
  @usageBase = UsageMod::Base.new(self, *args)
  begin
    @usageBase.parse_args(&block)
  rescue UsageMod::LongUsageRequested
    die_long
  rescue UsageMod::Error => usageError
    $TRACE.debug 1, usageError.backtrace.join("\n")
    die(usageError.message)
  rescue
    raise
  end
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(symbol, *args, &block) ⇒ Object

forward all other calls to UsageMod::Base class



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# File 'lib/Usage.rb', line 1038

def method_missing(symbol, *args, &block)
  $TRACE.debug 5, "Usage method missing: #{symbol}"
  @usageBase.send(symbol, *args, &block)
end

Instance Method Details

#ask_yes_no(str, default) ⇒ Object 



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# File 'lib/Usage.rb', line 1043

def ask_yes_no(str, default)
  while true
    print str + " [" + (default == UsageMod::YES_RESPONSE ? "Yn" : "yN") + "]? "
    $stdout.flush
    s = $stdin.gets
    case s 
    when /^$/
      return default
    when /^y/i
      return UsageMod::YES_RESPONSE
    when /^n/i
      return UsageMod::NO_RESPONSE
    end
  end
end

#die(message) ⇒ Object

Allows the program to die in a graceful manner. It displays

ERROR: the error message

It then calls exit (so it doesn’t return)



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# File 'lib/Usage.rb', line 997

def die(message)
    print_program_name
    print "ERROR: #{message}\n"
    print "\n"
    print_short_usage
    exit 1
end

#die_long ⇒ Object

Allows the program to die in a graceful manner. It displays

ERROR: the error message

followed by the usage string. It then calls exit (so it doesn’t return)



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# File 'lib/Usage.rb', line 1012

def die_long
  print_program_name
  print_short_usage
  print @usageBase.long_usage + "\n"
  exit 1
end

#print_program_name ⇒ Object

Prints out the program’s name in a graceful manner.

PROGRAM: program name



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# File 'lib/Usage.rb', line 1024

def print_program_name
    print "PROGRAM: #{$0}\n"
end

#print_short_usage ⇒ Object

Print out the short usage string (without the options)



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# File 'lib/Usage.rb', line 1031

def print_short_usage
  print "USAGE: #{File.basename($0)} #{@usageBase.usage}\n"
end