Class: HighLine

Inherits:
Object
  • Object
show all
Defined in:
lib/highline.rb,
lib/highline/question.rb

Overview

A HighLine object is a “high-level line oriented” shell over an input and an output stream. HighLine simplifies common console interaction, effectively replacing puts() and gets(). User code can simply specify the question to ask and any details about user interaction, then leave the rest of the work to HighLine. When HighLine.ask() returns, you’ll have to answer you requested, even if HighLine had to ask many times, validate results, perform range checking, convert types, etc.

Defined Under Namespace

Classes: Question, QuestionError

Constant Summary collapse

CLEAR =

Embed in a String to clear all previous ANSI sequences. This MUST be done before the program exits!

"\e[0m"
RESET =

An alias for CLEAR.

CLEAR
BOLD =

The start of an ANSI bold sequence.

"\e[1m"
DARK =

The start of an ANSI dark sequence. (Terminal support uncommon.)

"\e[2m"
UNDERLINE =

The start of an ANSI underline sequence.

"\e[4m"
UNDERSCORE =

An alias for UNDERLINE.

UNDERLINE
"\e[5m"
REVERSE =

The start of an ANSI reverse sequence.

"\e[7m"
CONCEALED =

The start of an ANSI concealed sequence. (Terminal support uncommon.)

"\e[8m"
BLACK =

Set the terminal’s foreground ANSI color to black.

"\e[30m"
RED =

Set the terminal’s foreground ANSI color to red.

"\e[31m"
GREEN =

Set the terminal’s foreground ANSI color to green.

"\e[32m"
YELLOW =

Set the terminal’s foreground ANSI color to yellow.

"\e[33m"
BLUE =

Set the terminal’s foreground ANSI color to blue.

"\e[34m"
MAGENTA =

Set the terminal’s foreground ANSI color to magenta.

"\e[35m"
CYAN =

Set the terminal’s foreground ANSI color to cyan.

"\e[36m"
WHITE =

Set the terminal’s foreground ANSI color to white.

"\e[37m"
ON_BLACK =

Set the terminal’s background ANSI color to black.

"\e[40m"
ON_RED =

Set the terminal’s background ANSI color to red.

"\e[41m"
ON_GREEN =

Set the terminal’s background ANSI color to green.

"\e[42m"
ON_YELLOW =

Set the terminal’s background ANSI color to yellow.

"\e[43m"
ON_BLUE =

Set the terminal’s background ANSI color to blue.

"\e[44m"
ON_MAGENTA =

Set the terminal’s background ANSI color to magenta.

"\e[45m"
ON_CYAN =

Set the terminal’s background ANSI color to cyan.

"\e[46m"
ON_WHITE =

Set the terminal’s background ANSI color to white.

"\e[47m"

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(input = $stdin, output = $stdout, wrap_at = nil, page_at = nil) ⇒ HighLine

Create an instance of HighLine, connected to the streams input and output.



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# File 'lib/highline.rb', line 88

def initialize( input = $stdin, output = $stdout,
	            wrap_at = nil, page_at = nil )
	@input   = input
	@output  = output
	@wrap_at = wrap_at
	@page_at = page_at
end

Instance Attribute Details

#page_at ⇒ Object

Set to an integer value to cause HighLine to page output lines over the indicated line limit. When nil, the default, no paging occurs.



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# File 'lib/highline.rb', line 105

def page_at
  @page_at
end

#wrap_at ⇒ Object

Set to an integer value to cause HighLine to wrap output lines at the indicated character limit. When nil, the default, no wrapping occurs.



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# File 'lib/highline.rb', line 100

def wrap_at
  @wrap_at
end

Instance Method Details

#agree(yes_or_no_question, character = nil) ⇒ Object

A shortcut to HighLine.ask() a question that only accepts “yes” or “no” answers (“y” and “n” are allowed) and returns true or false (true for “yes”). If provided a true value, character will cause HighLine to fetch a single character response.



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# File 'lib/highline.rb', line 113

def agree( yes_or_no_question, character = nil )
	ask(yes_or_no_question, lambda { |yn| yn.downcase[0] == ?y}) do |q|
		q.validate                 = /\Ay(?:es)?|no?\Z/i
		q.responses[:not_valid]    = 'Please enter "yes" or "no".'
		q.responses[:ask_on_error] = :question
		q.character                = character
	end
end

#ask(question, answer_type = String, &details) ⇒ Object

This method is the primary interface for user input. Just provide a question to ask the user, the answer_type you want returned, and optionally a code block setting up details of how you want the question handled. See HighLine.say() for details on the format of question, and HighLine::Question for more information about answer_type and what’s valid in the code block.



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# File 'lib/highline.rb', line 130

def ask( question, answer_type = String, &details ) # :yields: question
	@question = Question.new(question, answer_type, &details)
	
	say(@question)
	begin
		answer = @question.answer_or_default(get_response )
		unless @question.valid_answer?(answer)
			explain_error(:not_valid)
			raise QuestionError
		end
		
		answer = @question.convert(answer)
		
		if @question.in_range?(answer)
			answer
		else
			explain_error(:not_in_range)
			raise QuestionError
		end
	rescue QuestionError
		retry
	rescue ArgumentError
		explain_error(:invalid_type)
		retry
	rescue NameError
		raise if $!.is_a?(NoMethodError)
		explain_error(:ambiguous_completion)
		retry
	end
end

#color(string, *colors) ⇒ Object

This method provides easy access to ANSI color sequences, without the user needing to remember to CLEAR at the end of each sequence. Just pass the string to color, followed by a list of colors you would like it to be affected by. The colors can be HighLine class constants, or symbols (:blue for BLUE, for example). A CLEAR will automatically be embedded to the end of the returned String.



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# File 'lib/highline.rb', line 169

def color( string, *colors )
	colors.map! do |c|
		if c.is_a?(Symbol)
			self.class.const_get(c.to_s.upcase)
		else
			c
		end
	end
	"#{colors.join}#{string}#{CLEAR}"
end

#say(statement) ⇒ Object

The basic output method for HighLine objects. If the provided statement ends with a space or tab character, a newline will not be appended (output will be flush()ed). All other cases are passed straight to Kernel.puts().

The statement parameter is processed as an ERb template, supporting embedded Ruby code. The template is evaluated with a binding inside the HighLine instance, providing easy access to the ANSI color constants and the HighLine.color() method.



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# File 'lib/highline.rb', line 190

def say( statement )
	statement = statement.to_s
	return unless statement.length > 0
	
	template  = ERB.new(statement, nil, "%")
	statement = template.result(binding)
	
	statement = wrap(statement) unless @wrap_at.nil?
	statement = page_print(statement) unless @page_at.nil?
	
	if statement[-1, 1] == " " or statement[-1, 1] == "\t"
		@output.print(statement)
		@output.flush	
	else
		@output.puts(statement)
	end
end