Benny is happy to announce his next gem:
“lazyscript”
Dear list,
I hope this is useful for someone and I am curious what you think about
it.
== Overview
LazyScript offers an easy way to create text based applications that are
dealing with several interdependant parts and that may require input
from
a user (bascially selection of options and input).
This parts are called “Modes”. Each mode has got a corresponding dialog
with
its methods called “Screen”.
The name of the screen is the lowercase name of the mode.
All you have to do is to create subclasses of “Mode” and define the
methods
of the modes which will show up in the Screens.
And then you may define titles for the screens and additional entries to
jump from one mode-screen to another.
If you have the rubygem ncurses installed you even get ncurses based
dialogs
for free.
== Example of Usage
require ‘rubygems’
require_gem ‘lazyscript’
include LazyScript
loads the config file, it will be created for you, if it doesn’t exist
load_config(“myscript.yaml”)
defines a mode with the name ‘database’
class Database < Mode
the path shown in the status bar (where we are in the dialogs).
the name of a currently chosen database appended to this path
def path
“database/”
end
defines a hash of keys shown to select a certain database.
the values are the result you get
def select
{“database1” => “a”, “database2” => “b”, “database3” => “c”}
end
defines which methods should not be shown in the screen “database”
def hidden_methods()
[“add”, “delete”]
end
end
defines a mode with the name ‘schema’
class Schema < Mode
from(Database) forces a database to be selected before
we could deal with a schema. this results in a dialog popping up
to select a database from the list above (see Database#select)
and return to the schema screen after a database was chosen
then the name of the chosen database is shown in the path followed
by a dot and the name of the currently chosen schema
(if there is one chosen). since we use lazy evaluation
(see lazyvalue.rb) the database selection is one asked once
and then cached
def path
“#{from(Database)}.”
end
a method that requires some other input
def special_question
# see the gem “highline” for more infos of the syntax
# of “say” and “ask” (it even works with ncurses)
say(“I want to ask you some questions:”)
age = ask(“How old are you?”)
gender = ask(“Are you male / female?”, [:male, :female])
end
end
defines a mode with the name ‘table’
class Table < Mode
here first the selection of a database is forced and after that
the selection of a schema (see Schema#path)
def path
“#{from(Database)}.#{from(Schema)}.”
end
here we use from(Database) and from(Schema) again to get the
selected ones or force a selection if they haven’t been selected
before
if you want to know more about how you may define from(SomeThing) or
to(SomeThing) yourself look at the gem “FaceToFace”
def select
db = from(Database)
schema = from(Schema)
hsh= {“table1” => “”, “table2” => “”, “table3” => “”}
end
here an example how to use the add method to add a table
def add()
# force to rechoose database and scheme, even if they already have
# been chosen
HANDLER.reset(“database”)
HANDLER.reset(“schema”)
# get the new choices
db = from(Database)
schema = from(Schema)
# here Mode#add is called. in the block you place your normal code.
# if block return true, the action is concidered to be successful,
# if it returns false as unsuccessful
super() do |name|
# name is the name for the new table entered by the user
#say "added #{db}.#{schema}.#{name}"
true
end
end
here an example how to use the delete method to delete a table
def delete()
# force the selection of the table that should be deleted
table = from(Table)
# call Mode#delete to ask if the table should be deleted.
# if the response is "yes" then the block will
# be executed, otherwise the table screen will be shown
# if the block returns true, the deletion will be considered
# as successful, if false then as unsuccessful
super(table) do
# delete it
true
end
end
end
== Example of configuration file
- ‘main’ is the first screen shown when you start the application
- ‘children’ specifies other screens that may be reached from this
screen - ‘title’ is the title of the screen shown at the top of the screen
NOTE that YAML style requires indentation of 2 spaces - no tabs!
SCREENS:
main:
title: “\n\n#-- Welcome to our little Example --#\n”
children:
- database
- framework
- project
database:
title: Database
children:
- schema
- table
schema:
title: Schema
children:
- table
== Future
- the ncurses dialogs will have to be further refined
- add some cmdparse hacks to allow direct usage of the modes without
dialogs - maybe even implement the dialogs in a GUI lib (with fallback to
textmode)
and as webrick dialogs. this would enable us to write applications that
may
run with any interface without having to care about the interface
== Where may I find a complete example?
have a look at tests/example.rb
Project Website: http://rubyforge.org/projects/lazyscript/
Contact: [email protected]
