# # = Application Context # # Every application needs configuration and app-ctx provides a concise way of # doing it. # # For all applications (you are not a mouseclicker, are u?), once in a while # you need to supply some configuration values to overrule the built-in # defaults. The app-ctx gem does unify and organize built-in constants, # config files and commandline option with a clearly defined priority, from # low to high: # # - procedural: App::Config#set_default_values # - default values YAML file from next to the $0 script # - user supplied configuration file, eg.: –config=/tmp/foo.yml # - command line options and flags: –foo –bar=foo # # But for your application it is of no interesst from where the values are # coming: command line option: “–port=1234”, a user configuration file or # from the applications built-in default values. Therefor app-ctx combines # value settings from various sources into a single configuration hash. # # basically you have two ways to use it: # # require ‘app-ctx’ # of course,and than… # # 1. closures (see examples/run_with_block.rb) # # App::ctx.run do |context| … end # # where context object provides: # # values: the combined key and value settings # argv: remaining argument(not the options) of the command line # defaults_path: full path to the defaults file # # # 2. with a mainclass(see examples/run_with_class.rb) # # App::ctx.run YourClassHere # # for the second case(with a mainclass) an application instance of this class # is created. The first argument is than taken as method name and executed, # again with a context oject provided. # # $ ruby example/run_with_class show # # will result in the :show method beeing called: # # context = Config.new… # … # app = Simple.new… # app.show(context) # # # == Conversions # # Commandline options are strings only, but sometimes you need strongly typed # primitive values. app-ctx does automatically convert integer and float # values, see “examples/conversions.rb” for: # # $ ./examples/conversions.rb

# :f=>3.14 # typeof ‘i’: Fixnum # typeof ‘f’: Float # # $ ./examples/conversions.rb -i=17 -f=2.12 # :f=>2.12 # typeof ‘i’: Fixnum # typeof ‘f’: Float # # $ ./examples/conversions.rb -i=i -f=f # :f=>“f” # typeof ‘i’: String # typeof ‘f’: String # # # == Flags/Boolean values #

# Flags(options without values) are converted to boolean values, see # examples/boolean.rb: # # $ ruby ./examples/boolean.rb # :bool=>false # typeof ‘bool’: FalseClass # # $ ruby ./examples/boolean.rb –bool # :bool=>true # typeof ‘bool’: TrueClass # # # == Ruby Conversions #

# When Fixnum, Float and boolean conversion are not enough, as a last resort, # you can use ruby code directly for evaluation of option values. Replacing # ‘=’ with ‘:’ results in assigning the ruby evaluation value to the key, see # examples/ruby_conv.rb: # # $ ruby ./examples/ruby_conv.rb # :a=>[1, 2, 3, 4, 5, 6, 7, 8, 9, 10] # typeof ‘r’: Range # typeof ‘a’: Array # # $ ruby ./examples/ruby_conv.rb -r:2..3 -a:‘(-1..1).to_a’ # :a=>[-1, 0, 1] # typeof ‘r’: Range # typeof ‘a’: Array # # $ ruby ./examples/ruby_conv.rb -r:2..3 -a:(-1..1).to_a # :a=>[-1, 0, 1] # typeof ‘r’: Range # typeof ‘a’: Array # # # have fun # dirk # # vim: set tw=80 syntax=txt nosmartindent: