Class: Comparison::Presenter

Inherits:
Comparator show all
Extended by:
Forwardable
Includes:
ActionView::Helpers::TranslationHelper
Defined in:
lib/comparison/presenter.rb

Constant Summary collapse

ARROWS = 
{ up: '↑', down: '↓', none: '' }

Instance Attribute Summary

Attributes inherited from Comparator

#m, #n

Instance Method Summary collapse

Methods inherited from Comparator

#absolute, #initialize, #relative

Constructor Details

This class inherits a constructor from Comparison::Comparator

Instance Method Details

#arrow ⇒ Object

Returns the I18n translation for ‘comparison.icons`. (See also `#icon`.)

This method is intended to display a graphical representation of the comparison. Typically this would be an arrow pointing up or down.

The default implementation is as follows:

en:

comparison:
  arrows:
    positive_html: '↑'
    negative_html: '↓'
    nochange_html: ''

For example, to generate up and down arrows using Glyphicons included with Bootstrap, you could add the following translations to your application:

‘#arrows` and its sister method `#icon` perform roughly identical tasks with roughly identical intentions. The difference between the two methods is in the context in which they are intended to be used.

‘#arrows` is meant to be used from view contexts with limited functionality such as an HTML email. As such, the translations you specify should be simple enough, like HTML character entities, to work within said view context.

‘#icons` is meant to be used from full-featured view contexts. As such, `#icons` is the one to use to generate HTML tags.



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# File 'lib/comparison/presenter.rb', line 111

def arrow
  case
  when positive?
    t 'comparison.arrows.positive_html', default: ARROWS[:up]
  when negative?
    t 'comparison.arrows.negative_html', default: ARROWS[:down]
  else
    t 'comparison.arrows.nochange_html', default: ARROWS[:none]
  end
end

#classes ⇒ Object

Returns the I18n translation for ‘comparison.classes`. (See also `#css`.)

Use these translations to specify CSS classes for tags that contain comparison data. For example:

en:

comparison:
  classes:
    positive: 'comparison positive'
    negative: 'comparison negative'
    nochange: 'comparison nochange'

.comparison.positive 

color: #3c763d;
background-color: #dff0d8;

.comparison.negative 

color: #a94442;
background-color: #f2dede;

.comparison.nochange 

color: #777777;

content_tag cmp.difference, class: cmp.classes



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# File 'lib/comparison/presenter.rb', line 148

def classes
  case
  when positive?
    t 'comparison.classes.positive'
  when negative?
    t 'comparison.classes.negative'
  else
    t 'comparison.classes.nochange'
  end
end

#css ⇒ Object Also known as: style

Returns the I18n translation for ‘comparison.css`. (See also `#classes`.)

Use these translations to specify raw CSS style rules to be used when formatting comparison data. For example:

en:

comparison:
  css:
    positive: 'color: #3c763d; background-color: #dff0d8;'
    negative: 'color: #a94442; background-color: #f2dede;'
    nochange: 'color: #777777;'

content_tag cmp.difference, style: cmp.css

‘#css` and its sister method `#classes` perform very similar tasks. Use `#css` when you need to embed the CSS style rules in an HTML tag using the style attribute. Use `#classes` when you want have the CSS style rules defined in a class and want to add that class to the HTML tag.



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# File 'lib/comparison/presenter.rb', line 178

def css
  case
  when positive?
    t 'comparison.css.positive', default: ''
  when negative?
    t 'comparison.css.negative', default: ''
  else
    t 'comparison.css.nochange', default: ''
  end
end

#difference(**options) ⇒ Object

Returns ‘Comparator#absolute` presented as currency.



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# File 'lib/comparison/presenter.rb', line 17

def difference(**options)
  if positive?
    number_to_currency absolute, format: '+%u%n', **options
  else
    number_to_currency absolute, **options
  end
end

#icon ⇒ Object

Returns the I18n translation for ‘comparison.icons`. (See also `#arrow`.)

This method is intended to display a graphical representation of the comparison. Typically this would be an arrow pointing up or down.

No default implementation is included. You must provide the translations yourself or you will get missing translations.

For example, to generate up and down arrows using Glyphicons included with Bootstrap, you could add the following translations to your application:

en:

comparison:
  icons:
    positive_html: '<span class="glyphicon glyphicon-arrow-up"></span>'
    negative_html: '<span class="glyphicon glyphicon-arrow-down"></span>'
    nochange_html: '<span class="glyphicon glyphicon-minus"></span>'



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# File 'lib/comparison/presenter.rb', line 70

def icon
  case
  when positive?
    t 'comparison.icons.positive_html'
  when negative?
    t 'comparison.icons.negative_html'
  else
    t 'comparison.icons.nochange_html'
  end
end

#percentage(delimiter: ',', precision: 0, **options) ⇒ Object Also known as: change

Returns ‘Comparator#relative` formatted as a percentage.

If the relative percentage evaluates to Infinity or -Infinity, nil is returned. If it evaluates to NaN, 0 is returned.



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# File 'lib/comparison/presenter.rb', line 30

def percentage(delimiter: ',', precision: 0, **options)
  case
  when nan? || zero?
    number_to_percentage 0, precision: precision, **options
  when infinite?
    # TODO: Return nil, or lookup an optional representation in I18n?
    nil
  when positive?
    number_to_percentage relative, delimiter: delimiter,
      precision: precision, format: '+%n%', **options
  else
    number_to_percentage relative, delimiter: delimiter,
      precision: precision, **options
  end
end