CODEWITHSUNDEEP
rubymethods
tjhnc
tjhnc

Reputation: 143

Built-in Ruby methods

If there is a defined built in ruby method, is it always preferable to use the built-in method?

If I have code such as:

if i == 0

What is the advantage to instead using the built-in ruby method?

if i.zero?

Upvotes: 6

Views: 449

Answers (4)

Cary Swoveland
Cary Swoveland

Reputation: 110725

I've made a New Year's resolution to make greater use of Ruby methods that end with a question mark. I think doing do so will make my code more expressive and also cut down on errors. The most obvious example of the latter is using eql? instead of == (for comparing objects of class Object, not to be confused with equal?). But how often do you see x.eql? 7 instead of x == 7? Probably less often than you see x = 7, when x == 7 was intended.

Some others that seem to get less respect than they deserve include (the afore-mentioned) zero?, nonzero?, integer?, empty?, any?, all?, nil?, none?, one?, start_with? and end_with?.

Upvotes: 0

falsetru
falsetru

Reputation: 369274

i.zero? works only if i is Numeric object.

i = nil
i == 0
# => false
i.zero?
# NoMethodError: undefined method `zero?' for nil:NilClass
#        from (irb):5
#        from C:/Ruby200-x64/bin/irb:12:in `<main>'

Upvotes: 5

Малъ Скрылевъ
Малъ Скрылевъ

Reputation: 16505

I've written simple test:

require 'benchmark'

l = 0

funcs =
[ proc { l == 0 },
  proc { l.zero? },
]

def ctime func
   time = 0
   1000.times { time += Benchmark.measure { 1000.times { func.call } }.to_a[5].to_f }
   rtime = time /= 1000000
end

funcs.each {| func | p ctime( func ) }

# 4.385690689086914e-07
# 4.829726219177246e-07

As you can see :zero? method takes a few additional time (about 10%) against the :== method, so it is slower than :==. Second, since :zero? method is included only in Numeric class and its descendants, you can use it only on numbers.

Upvotes: 2

tckmn
tckmn

Reputation: 59303

As far as I know, those kinds of methods are for doing something like: 

array.delete_if &:zero?

It may be preferable to use == 0 in if statements and such for consistency, but this is now more of a matter of opinion.

If you think zero? is more readable, use it.

Upvotes: 2

Related Questions