Main-2.0.0

NAME
main.rb

SYNOPSIS
a class factory and dsl for generating command line programs real
quick

URI
http://rubyforge.org/projects/codeforpeople/
http://codeforpeople.com/lib/ruby/

INSTALL
gem install main

DESCRIPTION
main.rb features the following:

 - unification of option, argument, keyword, and environment

parameter
parsing
- auto generation of usage and help messages
- support for mode/sub-commands
- io redirection support
- logging hooks using ruby’s built-in logging mechanism
- intelligent error handling and exit codes
- use as dsl or library for building Main objects
- parsing user defined ARGV and ENV
- zero requirements for understanding the obtuse apis of any
command
line option parsers

in short main.rb aims to drastically lower the barrier to writing
uniform
command line applications.

for instance, this program

 require 'main'

 Main {
   argument 'foo'
   option 'bar'

   def run
     p params['foo']
     p params['bar']
     exit_success!
   end
 }

sets up a program which requires one argument, ‘bar’, and which
may accept one
command line switch, ‘–foo’ in addition to the single option/mode
which is always
accepted and handled appropriately: ‘help’, ‘–help’, ‘-h’. for
the most
part main.rb stays out of your command line namespace but insists
that your
application has at least a help mode/option.

main.rb supports sub-commands in a very simple way

 require 'main'

 Main {
   mode 'install' do
     def run() puts 'installing...' end
   end

   mode 'uninstall' do
     def run() puts 'uninstalling...' end
   end
 }

which allows you a program called ‘a.rb’ to be invoked as

 ruby a.rb install

and

 ruby a.rb uninstall

for simple programs main.rb is a real time saver but it’s for more
complex
applications where main.rb’s unification of parameter parsing, class
configuration dsl, and auto-generation of usage messages can
really streamline
command line application development. for example the following
‘a.rb’
program:

 require 'main'

 Main {
   argument('foo'){
     cast :int
   }
   keyword('bar'){
     arity 2
     cast :float
     defaults 0.0, 1.0
   }
   option('foobar'){
     argument :optional
     description 'the foobar option is very handy'
   }
   environment('BARFOO'){
     cast :list_of_bool
     synopsis 'export barfoo=value'
   }

   def run
     p params['foo'].value
     p params['bar'].values
     p params['foobar'].value
     p params['BARFOO'].value
   end
 }

when run with a command line of

 BARFOO=true,false,false ruby a.rb 42 bar=40 bar=2 --foobar=a

will produce

 42
 [40.0, 2.0]
 "a"
 [true, false, false]

while a command line of

 ruby a.rb --help

will produce

 NAME
   a.rb

 SYNOPSIS
   a.rb foo [bar=bar] [options]+

 PARAMETERS
   * foo [ 1 -> int(foo) ]

   * bar=bar [ 2 ~> float(bar=0.0,1.0) ]

   * --foobar=[foobar] [ 1 ~> foobar ]
       the foobar option is very handy

   * --help, -h

   * export barfoo=value

and this shows how all of argument, keyword, option, and
environment parsing
can be declartively dealt with in a unified fashion - the dsl for all
parameter types is the same - and how auto synopsis and usage
generation saves
keystrokes. the parameter synopsis is compact and can be read as

   * foo [ 1 -> int(foo) ]

     'one argument will get processed via int(argument_name)'

       1        : one argument
       ->       : will get processed (the argument is required)
       int(foo) : the cast is int, the arg name is foo

   * bar=bar [ 2 ~> float(bar=0.0,1.0) ]

     'two keyword arguments might be processed via float

(bar=0.0,1.0)’

       2                  : two arguments
       ~>                 : might be processed (the argument is

optional)
float(bar=0.0,1.0) : the cast will be float, the default
values are
0.0 and 1.0

   * --foobar=[foobar] [ 1 ~> foobar ]

     'one option with optional argument may be given directly'

   * --help, -h

     no synopsis, simple switch takes no args and is not required

   * export barfoo=value

     a user defined synopsis

SAMPLES

<========< samples/a.rb >========>

~ > cat samples/a.rb

 require 'main'

 ARGV.replace %w( 42 ) if ARGV.empty?

 Main {
   argument('foo'){
     required                    # this is the default
     cast :int                   # value cast to Fixnum
     validate{|foo| foo == 42}   # raises error in failure case
     description 'the foo param' # shown in --help
   }

   def run
     p params['foo'].given?
     p params['foo'].value
   end
 }

~ > ruby samples/a.rb

 true
 42

~ > ruby samples/a.rb --help

 NAME
   a.rb

 SYNOPSIS
   a.rb foo [options]+

 PARAMETERS
   foo (1 -> int(foo))
       the foo param
   --help, -h

<========< samples/b.rb >========>

~ > cat samples/b.rb

 require 'main'

 ARGV.replace %w( 40 1 1 ) if ARGV.empty?

 Main {
   argument('foo'){
     arity 3                             # foo will given three

times
cast :int # value cast to Fixnum
validate{|foo| [40,1].include? foo} # raises error in
failure case
description ‘the foo param’ # shown in --help
}

   def run
     p params['foo'].given?
     p params['foo'].values
   end
 }

~ > ruby samples/b.rb

 true
 [40, 1, 1]

~ > ruby samples/b.rb --help

 NAME
   b.rb

 SYNOPSIS
   b.rb foo [options]+

 PARAMETERS
   foo (3 -> int(foo))
       the foo param
   --help, -h

<========< samples/c.rb >========>

~ > cat samples/c.rb

 require 'main'

 ARGV.replace %w( foo=40 foo=2 bar=false ) if ARGV.empty?

 Main {
   keyword('foo'){
     required  # by default keywords are not required
     arity 2
     cast :float
   }
   keyword('bar'){
     cast :bool
   }

   def run
     p params['foo'].given?
     p params['foo'].values
     p params['bar'].given?
     p params['bar'].value
   end
 }

~ > ruby samples/c.rb

 true
 [40.0, 2.0]
 true
 false

~ > ruby samples/c.rb --help

 NAME
   c.rb

 SYNOPSIS
   c.rb foo=foo [bar=bar] [options]+

 PARAMETERS
   foo=foo (2 -> float(foo))
   bar=bar (1 ~> bool(bar))
   --help, -h

<========< samples/d.rb >========>

~ > cat samples/d.rb

 require 'main'

 ARGV.replace %w( --foo=40 -f2 ) if ARGV.empty?

 Main {
   option('foo', 'f'){
     required  # by default options are not required, we could

use ‘foo=foo’
# above as a shortcut
argument_required
arity 2
cast :float
}

   option('bar=[bar]', 'b'){  # note shortcut syntax for optional

args
# argument_optional # we could also use this method
cast :bool
default false
}

   def run
     p params['foo'].given?
     p params['foo'].values
     p params['bar'].given?
     p params['bar'].value
   end
 }

~ > ruby samples/d.rb

 true
 [40.0, 2.0]
 nil
 false

~ > ruby samples/d.rb --help

 NAME
   d.rb

 SYNOPSIS
   d.rb --foo=foo [options]+

 PARAMETERS
   --foo=foo, -f (2 -> float(foo))
   --bar=[bar], -b (1 ~> bool(bar=false))
   --help, -h

DOCS

  • test/main.rb
  • vim -o lib/main.rb lib/main/*
  • API section below

HISTORY
2.0.0
- removed need for proxy.rb via Main::Base.wrap_run!
- added error handling hooks for parameter parsing
- bundled arrayfields, attributes, and pervasives although gems
are tried
first
- softened error messages for parameter parsing errors: certain
classes of
errors are now ‘softspoken’ and print only the message, not
the entire
stacktrace, to stderr. much nicer for users. this is
configurable.
- added subcommand/mode support
- added support for user defined exception handling on top level
exceptions/exits
- added support for negative arity. this users ruby’s own arity
semantics, for example:

     lambda{|*a|}.arity     == -1
     lambda{|a,*b|}.arity   == -2
     lambda{|a,b,*c|}.arity == -3
     ...

   in otherwords parameters now support 'zero or more', 'one or

more’ …
‘n or more’ argument semantics

API

Main {

########################################################################

CLASS LEVEL

API #

########################################################################

the name of the program, auto-set and used in usage

 program 'foo.rb'

a short description of program functionality, auto-set and used

in usage

 synopsis "foo.rb arg [options]+"

long description of program functionality, used in usage iff set

 description <<-hdoc
   this text will automatically be indented to the right level.

   it should describe how the program works in detail
 hdoc

used in usage iff set

 author '[email protected]'

used in usage

 version '0.0.42'

stdin/out/err can be anthing which responds to read/write or a

string

which will be opened as in the appropriate mode

 stdin '/dev/null'
 stdout '/dev/null'
 stderr open('/dev/null', 'w')

the logger should be a Logger object, something ‘write’-able, or

a string

which will be used to open the logger. the logger_level

specifies the

initalize verbosity setting, the default is Logger::INFO

 logger(( program + '.log' ))
 logger_level Logger::DEBUG

you can configure exit codes. the defaults are shown

 exit_success # 0
 exit_failure # 1
 exit_warn    # 42

the usage object is rather complex. by default it’s an object

which can

be built up in sections using the

usage[“BUGS”] = "something about bugs’

syntax to append sections onto the already pre-built usage

message which

contains program, synopsis, parameter descriptions and the like

however, you always replace the usage object wholesale with one

of your

chosing like so

 usage <<-txt
   my own usage message
 txt

########################################################################

MODE

API #

########################################################################

modes are class factories that inherit from their parent class.

they can

be nested arbitrarily deep. usage messages are tailored for

each mode.

modes are, for the most part, independant classes but parameters

are

always a superset of the parent class - a mode accepts all of

it’s parents

paramters plus and additional ones

 option 'inherited-option'
 argument 'inherited-argument'

 mode 'install' do
   option 'force' do
     description 'clobber existing installation'
   end

   def run
     inherited_method()
     puts 'installing...'
   end

   mode 'docs' do
     description 'installs the docs'

     def run
       puts 'installing docs...'
     end
   end
 end

 mode 'un-install' do
   option 'force' do
     description 'remove even if dependancies exist'
   end

   def run
     inherited_method()
     puts 'un-installing...'
   end
 end

 def run
   puts 'no mode yo?'
 end

 def inherited_method
   puts 'superclass_method...'
 end

########################################################################

PARAMETER

API #

########################################################################

all the parameter types of argument|keyword|option|environment

share this

api. you must specify the type when the parameter method is used.

alternatively used one of the shortcut methods

argument|keyword|option|environment. in otherwords

parameter(‘foo’){ type :option }

is synonymous with

option(‘foo’){ }

 option 'foo' {
 #
 # required - whether this paramter must by supplied on the

command line.
# note that you can create ‘required’ options with this keyword
#
required # or required true
#
# argument_required - applies only to options.
#
argument_required # argument :required
#
# argument_optional - applies only to options.
#
argument_optional # argument :optional
#
# cast - should be either a lambda taking one argument, or a symbol
# designation one of the built in casts defined in Main::Cast.
supported
# types are :boolean|:integer|:float|:numeric|:string|:uri.
built-in
# casts can be abbreviated
#
cast :int
#
# validate - should be a lambda taking one argument and returning
# true|false
#
validate{|int| int == 42}
#
# synopsis - should be a concise characterization of the
paramter. a
# default synopsis is built automatically from the parameter. this
# information is displayed in the usage message
#
synopsis ‘–foo’
#
# description - a longer description of the paramter. it
appears in the
# usage also.
#
description ‘a long description of foo’
#
# arity - indicates how many times the parameter should appear
on the
# command line. the default is one. negative arities are
supported and
# follow the same rules as ruby methods/procs.
#
arity 2
#
# default - you can provide a default value in case none is
given. the
# alias ‘defaults’ reads a bit nicer when you are giving a list of
# defaults for paramters of > 1 arity
#
defaults 40, 2
}

########################################################################

INSTANCE LEVEL

API #

########################################################################

you must define a run method. it is the only method you must

define.

 def run
   #
   # all parameters are available in the 'params' hash and via

the alias
# ‘param’. it can be indexed via string or symbol. the
values are all
# Main::Parameter objects
#
foo = params[‘foo’]
#
# the given? method indicates whether or not the parameter was
given on
# the commandline/environment, etc. in particular this will
not be true
# when a default value was specified but no parameter was given
#
foo.given?
#
# the list of all values can be retrieved via ‘values’. note
that this
# is always an array.
#
p foo.values
#
# the first value can be retrieved via ‘value’. note that
this
# never an array.
#
p foo.value
#
# the methods debug|info|warn|error|fatal are delegated to the
logger
# object
#
info{ “this goes to the log” }
#
# you can set the exit_status at anytime. this status is used
when
# exiting the program. exceptions cause this to be
ext_failure if, and
# only if, the current value was exit_success. in otherwords an
# un-caught exception always results in a failing exit_status
#
exit_status exit_failure
#
# a few shortcuts both set the exit_status and exit the program.
#
exit_success!
exit_failure!
exit_warn!
end

}

enjoy.

a @ http://codeforpeople.com/

From: ara.t.howard [mailto:[email protected]]

Subject: [ANN] main-2.0.0

quick qs:

  1. how to invoke -h inside program.
    currently i use something like [exec “ruby #{FILE} -h”]

    i tried using “usage[]” but i think it’s reinventing since -h if fine
    for me already.

  2. required args that fail just gives/raise errors which is not so user
    friendly. How can i capture error cleanly? so i can display a user
    friendly error (and i also want to invoke help thereafter). Maybe
    require may need a block for the error to display, like,

    required {|error| code_here}

    or

    def err err_obj
    end

    ie, main calls err if it exists

    but i still would not know what to put on err

Right now, i set required args back to optional and then i have to ask
if args was given?

  1. how can i access all the args and options i set? I’d like to change
    my synopsis automatically and beautifully :slight_smile:

sorry for the many questions, ara.
Thank you for main. It’s very cool.

kind regards -botp

Great, I’m looking forward to using this

Fantastic! I always thought there should be a more Ruby-ish way of
handling things like this.

This probably won’t make it into any of my current projects, but I’ll
definitely be using it in the future.

Thanks!
Jeremy

On 10/18/07, ara.t.howard [email protected] wrote:

http://codeforpeople.com/lib/ruby/
- auto generation of usage and help messages
in short main.rb aims to drastically lower the barrier to writing

which is always
Main {

really streamline
keyword(‘bar’){
synopsis ‘export barfoo=value’
when run with a command line of
while a command line of

   * export barfoo=value
     'one argument will get processed via int(argument_name)'
       2                  : two arguments
   * --help, -h

     validate{|foo| foo == 42}   # raises error in failure case

failure case

   keyword('bar'){

   c.rb

     required  # by default options are not required, we could
     cast :bool

   d.rb
  • test/main.rb
    • softened error messages for parameter parsing errors: certain

used in usage

syntax to append sections onto the already pre-built usage

they can

   mode 'docs' do
     description 'remove even if dependancies exist'
 end

API #

parameter(‘foo’){ type :option }

 #
 # cast - should be either a lambda taking one argument, or a symbol
 #

appears in the
arity 2
########################################################################
def run
given on
p foo.values
#
#
enjoy.


http://www.jeremymcanally.com/

My books:
Ruby in Practice

My free Ruby e-book
http://www.humblelittlerubybook.com/

My blogs:
http://www.mrneighborly.com/
http://www.rubyinpractice.com/

On Oct 18, 2007, at 10:46 PM, Peña, Botp wrote:

From: ara.t.howard [mailto:[email protected]]

Subject: [ANN] main-2.0.0

quick qs:

  1. how to invoke -h inside program.
    currently i use something like [exec “ruby #{FILE} -h”]

    i tried using “usage[]” but i think it’s reinventing since -h if
    fine for me already.

cfp:~/src/ruby/main/main-2.0.0 > cat a.rb
require ‘main’

Main {
option ‘foobar’

 def run
   print usage.to_s
   exit
 end

}

cfp:~/src/ruby/main/main-2.0.0 > ruby a.rb
NAME
a.rb

SYNOPSIS
a.rb [options]+

PARAMETERS
–foobar
–help, -h

the reason that the ‘to_s’ is required is that the usage returns and
object that inherits from array and ruby treats ‘puts an_array’
specially. i should changed that in the next version… regardless
‘usage.to_s’ will continue to work.

  1. required args that fail just gives/raise errors which is not so
    user friendly.

i think 2.0.0 addresses this (common) complaint:

cfp:~/src/ruby/main/main-2.0.0 > cat a.rb
require ‘main’

Main {
argument(‘foobar’){ required }

run(){ puts Main.version }
}

cfp:~/src/ruby/main/main-2.0.0 > ruby a.rb foobar
2.0.0

cfp:~/src/ruby/main/main-2.0.0 > ruby a.rb
argument(foobar) not given

is that ok?

How can i capture error cleanly? so i can display a user friendly
error (and i also want to invoke help thereafter). Maybe require
may need a block for the error to display, like,

hmmmm. right now you, in 2.0.0, you can define ‘handle_exception’ on
your class but you will need to handle all exceptions in that
method… that’s not great i realize. in 2.0.0 i’ve added the
concept of ‘Softspoken’ errors. these are errors that, rather than
dumping a stacktrace in the log/stderr - simple print their message.
that’s how the ‘argument(foobar) not given’ above is printed - it’s a
‘Softspoken’ error and this is it’s message. now, as to the question
of how to further handle errors but printing usage, etc… that’s
harder. i’d personally NOT print usage after the error and instead
suggest to the user to run the program with ‘-h’ because a long usage
message printed after and error will cause the error to scroll off a
small terminal… still it’s a real need…

required {|error| code_here}

or

def err err_obj
end

ie, main calls err if it exists

but i still would not know what to put on err

ok i like this idea. the general concept is that parameter can have
their own error handlers - let me chew on this a little bit and try
to get a sample impl online for you to play with…

Right now, i set required args back to optional and then i have to
ask if args was given?

oh that’s hacking we don’t want to doing that! :wink:

  1. how can i access all the args and options i set? I’d like to
    change my synopsis automatically and beautifully :slight_smile:

cfp:~/src/ruby/main/main-2.0.0 > cat a.rb
require ‘main’

Main {
argument ‘foobar’
argument ‘barfoo’
option ‘a’
option ‘b’

run(){ params.each{|pm| p pm} }
}

cfp:~/src/ruby/main/main-2.0.0 > ruby a.rb foobar barfoo --a --b
#<Main::Parameter::Argument:0x6c034 @given=true, @type=:argument,
@arity=1, @values=[“foobar”], @names=[“foobar”], @defaults=[],
@cast=nil, @required=true, @validate=nil>
#<Main::Parameter::Argument:0x6b558 @given=true, @type=:argument,
@arity=1, @values=[“barfoo”], @names=[“barfoo”], @defaults=[],
@cast=nil, @required=true, @validate=nil>
#<Main::Parameter::Option:0x6aa7c @given=true, @type=:option,
@arity=1, @values=[true], @names=[“a”], @defaults=[], @cast=nil,
@required=false, @argument=nil, @validate=nil>
#<Main::Parameter::Option:0x69e24 @given=true, @type=:option,
@arity=1, @values=[true], @names=[“b”], @defaults=[], @cast=nil,
@required=false, @argument=nil, @validate=nil>
#<Main::Parameter::Option:0x67a0c @given=nil, @type=:option,
@arity=1, @names=[“help”, “h”], @defaults=[], @required=false,
@argument=nil>

i’d be interested to see what you come up with for an auto usage
message - that part was very hard for me and i’m not sure mine is the
best.

sorry for the many questions, ara.
Thank you for main. It’s very cool.

glad you are using it, and the feedback is really welcome - it’s
surprisingly difficult to get this working smoothly for even a modest
sample of command line apps - there are a lot of variables! :wink:

look for main-2.0.1 later today…

cheers.

a @ http://codeforpeople.com/

On Oct 19, 2007, at 9:41 PM, Peña, Botp wrote:

object that inherits from array and ruby treats ‘puts an_array’

specially. i should changed that in the next version… regardless

‘usage.to_s’ will continue to work.

no problem, ara. The usage.to_s is good enough.

great. in 2.1.0 (on rubyforge now) you can just use ‘help!’ which
calls ‘print usage.to_s; exit’ for you. i’ll rework the Usage class
to be and Array delegate rather than an Array subclass soon. it
annoys me that ‘puts usage’ does not work…

where to add more :slight_smile:

eg, i want to add sections like “other info”, “gotchas”,
“copyright”, “reporting bugs”, and “see also”.

oh. the Usage class is already setup to do that. simply do

usage[‘gotchas’] = huge_block_of_text

and it will automatically be included in a nicely formatted way.

it’s working great. really. my suggestions were purely cosmetics.
and btw, the new mode option is cool.
many thanks again.

kind regards -botp

glad to hear it - 2.1.0 also addresses your error handling issue:

cfp:~/src/ruby/main/main-2.1.0 > cat a.rb
require ‘main’

puts Main.version

Main {
argument ‘x’ do
error :before do
puts ‘this fires before normal error handling using
#instance_eval…’
end

 error do
   puts 'this fires *instead of* normal error handling using

#instance_eval…’
end

 error :after do
   puts 'this fires *after* normal error handling using

#instance_eval…’
end
end

run(){ p param[‘x’].given? }
}

cfp:~/src/ruby/main/main-2.1.0 > ruby -I lib a.rb
2.1.0
this fires before normal error handling using #instance_eval
this fires instead of normal error handling using #instance_eval
this fires after normal error handling using #instance_eval

in fact, 2.1.0 allows any exception to specify it’s own error
handlers - check out lib/main/base.rb and grep for ‘handler’.

kind regards.

a @ http://codeforpeople.com/

From: ara.t.howard [mailto:[email protected]]

def run

print usage.to_s

arggh, i did not try the to_s :slight_smile:
thanks

exit

end

the reason that the ‘to_s’ is required is that the usage returns and

object that inherits from array and ruby treats ‘puts an_array’

specially. i should changed that in the next version… regardless

‘usage.to_s’ will continue to work.

no problem, ara. The usage.to_s is good enough.

i’d be interested to see what you come up with for an auto usage

message - that part was very hard for me and i’m not sure

mine is the

best.

no, the automessage part is fine.
my plan really is to add more info on --help and i was looking where to
add more :slight_smile:

eg, i want to add sections like “other info”, “gotchas”, “copyright”,
“reporting bugs”, and “see also”.

glad you are using it, and the feedback is really welcome - it’s

surprisingly difficult to get this working smoothly for even

a modest

sample of command line apps - there are a lot of variables! :wink:

look for main-2.0.1 later today…

it’s working great. really. my suggestions were purely cosmetics. and
btw, the new mode option is cool.
many thanks again.

kind regards -botp

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