Add new Performance/BigDecimalWithNumericArgument cop

[fatkodima]

This is a simple one.

Related link - fastruby/fast-ruby#172

I believe there is a better name for this cop.

It is faster to pass string argument to BigDecimal than numeric arguments.

# bad
BigDecimal(1, 2)
BigDecimal(1.2, 3, exception: true)

# good
BigDecimal('1', 2)
BigDecimal('1.2', 3, exception: true)

Benchmark

require 'benchmark/ips'
require 'bigdecimal'

Benchmark.ips do |x|
  x.report("BigDecimal('1')")  { BigDecimal('1') }
  x.report("BigDecimal(1)")    { BigDecimal(1) }
  x.compare!
end

Benchmark.ips do |x|
  x.report("BigDecimal('1.0', 2)")  { BigDecimal('1.0', 2) }
  x.report("BigDecimal(1.0, 2)")    { BigDecimal(1.0, 2) }
  x.compare!
end

Results

Warming up --------------------------------------
     BigDecimal('1')   179.524k i/100ms
       BigDecimal(1)   114.825k i/100ms
Calculating -------------------------------------
     BigDecimal('1')      1.782M (± 3.9%) i/s -      8.976M in   5.046628s
       BigDecimal(1)      1.107M (± 6.5%) i/s -      5.512M in   5.002115s

Comparison:
     BigDecimal('1'):  1781639.0 i/s
       BigDecimal(1):  1106879.7 i/s - 1.61x  (± 0.00) slower

Warming up --------------------------------------
BigDecimal('1.0', 2)   151.605k i/100ms
  BigDecimal(1.0, 2)    34.490k i/100ms
Calculating -------------------------------------
BigDecimal('1.0', 2)      1.519M (± 4.6%) i/s -      7.580M in   5.001610s
  BigDecimal(1.0, 2)    339.573k (± 5.0%) i/s -      1.724M in   5.093169s

Comparison:
BigDecimal('1.0', 2):  1519109.1 i/s
  BigDecimal(1.0, 2):   339573.1 i/s - 4.47x  (± 0.00) slower

[fatkodima]

Updated.

[fatkodima]

Updated with new name.

[koic]

Great activity!