Number formatting + subscriptions

[Douglas Livingstone]

Hi all,

I want to make strings like this:

$100.00 plus $22.00 per month
$100.00
$22.00 per week
free (I want this when both numbers are zero)

Generally: [one off fee] plus [fee per billing cycle] per [billing cycle length]

Based on this input:

per_license_cost (= one off fee)
per_cycle_cost (= fee per cycle)
currency_symbol (=$)
cycle_length (= a string: 'day' | 'week' | 'month' | 'year')

I have working code, and in any other language I'd take the uglyness
for granted, but in Ruby I still have hope. So, what would be a better
way to write this? I've put the code I put together at the bottom.

Thanks,
Douglas


The code:

def human_price
if per_license_cost.zero? and per_cycle_cost.zero?
'free'
elsif per_cycle_cost.zero?
human_per_license_cost
elsif per_license_cost.zero?
human_per_cycle_cost
else
human_per_license_cost + ' plus ' + human_per_cycle_cost
end
end

def currency_symbol
'$' # fine for now... should I think about a Money class to manage this?
end

private

def human_cost(number)
human = number.to_s
number = if number.abs.to_s.length > 2
human[-2, 0] = '.'
human
elsif number.abs.to_s.length == 2
'0.' + human
elsif number.abs.to_s.length == 1
'0.0' + human
else
'0.00'
end
return currency_symbol + number
end

def human_per_license_cost
human_cost(per_license_cost)
end

def human_per_cycle_cost
human_cost(per_cycle_cost) + ' per ' + cycle_length
end

 

[Florian Groß]

I want to make strings like this:

$100.00 plus $22.00 per month
$100.00
$22.00 per week
free (I want this when both numbers are zero)

Generally: [one off fee] plus [fee per billing cycle] per [billing cycle length]

I have working code, and in any other language I'd take the uglyness
for granted, but in Ruby I still have hope. So, what would be a better
way to write this? I've put the code I put together at the bottom.

I'll try to start from scratch so please point any errors I might have
introduced:

# Note that this is not designed to work properly with Floats as it
# directly compares to 0 -- use a delta if it also should work with
# Floats.
def human_price(currency, base_fee, cycle_fee, cycle_length)
has_base_fee = base_fee != 0
has_cycle_fee = cycle_fee != 0
result = ""

result << "%s%.2f" % [currency, base_fee] if has_base_fee

if has_cycle_fee then
result << " plus " if has_base_fee
result << "%s%.2f per %s" % [currency, cycle_fee, cycle_length]
end

result = "free" if result.empty?

return result
end

The formating of a single price could be out-factored, but I think in
this simple case it is still reasonable to just have the logic two times
in the method...

 

[Douglas Livingstone]

The formating of a single price could be out-factored, but I think in
this simple case it is still reasonable to just have the logic two times
in the method...

Yes, you're right; when I was looking for string formatting, I didn't
see the % operator so my logic was bloated, so I factored it out. But
with your much neater logic it doesn't need that,so thanks very much!

Douglas