Checking if a variable is not nil and not zero in ruby

Question

I am using the following code to check if a variable is not nil and not zero  if discount    nil  amp  amp  discount    0         end   Is there a better way to do this

User · Answer

I believe the following is good enough for ruby code   I don t think I could write a unit test that shows any difference between this and the original   if discount    0 end

User · Answer

You can take advantage of the NilClass provided  to i method  which will return zero for nil values   unless discount to i zero      Code here end   If discount can be fractional numbers  you can use  to f instead  to prevent the number from being rounded to zero

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You could do this   if   discount nil   amp  amp   discount zero     The order is important here  because if discount is nil  then it will not have a zero  method  Ruby s short-circuit evaluation should prevent it from trying to evaluate discount zero   however  if discount is nil

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From Ruby 2 3 0 onward  you can combine the safe navigation operator   amp    with Numeric nonzero    amp   returns nil if the instance was nil and nonzero  - if the number was 0   if discount amp  nonzero          end   Or postfix   do something if discount amp  nonzero

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class Object   def nil zero      self nil     self    0   end end    which lets you do nil nil zero    returns true 0 nil zero      returns true 1 nil zero      returns false  a  nil zero    returns false  unless discount nil zero      do stuff    end   Beware of the usual disclaimers    great power responsibility  monkey patching leading to the dark side etc

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def is nil and zero data       data blank     data    0  end     If we pass    it will return false whereas blank  returns true  Same is the case when data   false blank  returns true for nil  false  empty  or a whitespace string  So it s better to use blank  method to avoid empty string as well

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if discount and discount    0      end   update  it will false for discount   false

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def is nil and zero data       data blank     data    0  end     If we pass    it will return false whereas blank  returns true  Same is the case when data   false blank  returns true for nil  false  empty  or a whitespace string  So it s better to use blank  method to avoid empty string as well

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if  discount  0     0        end

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unless discount nil     discount    0         end

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I prefer using a more cleaner approach      val to i zero    val to i will return a 0 if val is a nil   after that  all we need to do is check whether the final value is a zero

User · Answer

From Ruby 2 3 0 onward  you can combine the safe navigation operator   amp    with Numeric nonzero    amp   returns nil if the instance was nil and nonzero  - if the number was 0   if discount amp  nonzero          end   Or postfix   do something if discount amp  nonzero

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ok  after 5 years have passed      if discount try  nonzero        end   It s important to note that try is defined in the ActiveSupport gem  so it is not available in plain ruby

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You could initialize discount to 0 as long as your code is guaranteed not to try and use it before it is initialized   That would remove one check I suppose  I can t think of anything else

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if  discount  0     0        end

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if discount nil     discount    0    do something  end

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class Object   def nil zero      self nil     self    0   end end    which lets you do nil nil zero    returns true 0 nil zero      returns true 1 nil zero      returns false  a  nil zero    returns false  unless discount nil zero      do stuff    end   Beware of the usual disclaimers    great power responsibility  monkey patching leading to the dark side etc

User · Answer

I believe the following is good enough for ruby code   I don t think I could write a unit test that shows any difference between this and the original   if discount    0 end

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unless discount nil     discount    0         end

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unless  nil  0  include  discount           end

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When dealing with a database record  I like to initialize all empty values with 0  using the migration helper   add column  products   price   integer  default  0

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I believe the following is good enough for ruby code   I don t think I could write a unit test that shows any difference between this and the original   if discount    0 end

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unless  nil  0  include  discount           end

User · Answer

When dealing with a database record  I like to initialize all empty values with 0  using the migration helper   add column  products   price   integer  default  0

User · Answer

You could do this   if   discount nil   amp  amp   discount zero     The order is important here  because if discount is nil  then it will not have a zero  method  Ruby s short-circuit evaluation should prevent it from trying to evaluate discount zero   however  if discount is nil

User · Answer

class Object   def nil zero      self nil     self    0   end end    which lets you do nil nil zero    returns true 0 nil zero      returns true 1 nil zero      returns false  a  nil zero    returns false  unless discount nil zero      do stuff    end   Beware of the usual disclaimers    great power responsibility  monkey patching leading to the dark side etc

User · Answer

I believe the following is good enough for ruby code   I don t think I could write a unit test that shows any difference between this and the original   if discount    0 end

User · Answer

You could do this   if   discount nil   amp  amp   discount zero     The order is important here  because if discount is nil  then it will not have a zero  method  Ruby s short-circuit evaluation should prevent it from trying to evaluate discount zero   however  if discount is nil

User · Answer

You can convert your empty row to integer value and check zero       to i zero    gt  true nil to i zero    gt  true

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You could initialize discount to 0 as long as your code is guaranteed not to try and use it before it is initialized   That would remove one check I suppose  I can t think of anything else

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You could initialize discount to 0 as long as your code is guaranteed not to try and use it before it is initialized   That would remove one check I suppose  I can t think of anything else

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Alternative solution is to use Refinements  like so   module Nothingness   refine Numeric do     alias method  nothing    zero    end    refine NilClass do     alias method  nothing    nil    end end  using Nothingness  if discount nothing      do something end

User · Answer

You could do this   if   discount nil   amp  amp   discount zero     The order is important here  because if discount is nil  then it will not have a zero  method  Ruby s short-circuit evaluation should prevent it from trying to evaluate discount zero   however  if discount is nil

User · Answer

You can take advantage of the NilClass provided  to i method  which will return zero for nil values   unless discount to i zero      Code here end   If discount can be fractional numbers  you can use  to f instead  to prevent the number from being rounded to zero

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if discount nil     discount    0    do something  end

User · Answer

Yes  we do have a clean way in ruby  discount to f zero   This check handles good amount of cases i e  discount may be nil  discount may be int 0  discount may be float 0 0  discount may be string  quot 0 0 quot    quot 0 quot

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class Object   def nil zero      self nil     self    0   end end    which lets you do nil nil zero    returns true 0 nil zero      returns true 1 nil zero      returns false  a  nil zero    returns false  unless discount nil zero      do stuff    end   Beware of the usual disclaimers    great power responsibility  monkey patching leading to the dark side etc

User · Answer

unless  nil  0  include  discount           end

User · Answer

I prefer using a more cleaner approach      val to i zero    val to i will return a 0 if val is a nil   after that  all we need to do is check whether the final value is a zero

User · Answer

Yes  we do have a clean way in ruby  discount to f zero   This check handles good amount of cases i e  discount may be nil  discount may be int 0  discount may be float 0 0  discount may be string  quot 0 0 quot    quot 0 quot

User · Answer

unless discount nil     discount    0         end

User · Answer

You could initialize discount to 0 as long as your code is guaranteed not to try and use it before it is initialized   That would remove one check I suppose  I can t think of anything else

User · Answer

Alternative solution is to use Refinements  like so   module Nothingness   refine Numeric do     alias method  nothing    zero    end    refine NilClass do     alias method  nothing    nil    end end  using Nothingness  if discount nothing      do something end

User · Answer

ok  after 5 years have passed      if discount try  nonzero        end   It s important to note that try is defined in the ActiveSupport gem  so it is not available in plain ruby

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unless discount nil     discount    0         end

User · Answer

if  discount  0     0        end

User · Answer

if discount and discount    0      end   update  it will false for discount   false

User · Answer

You can convert your empty row to integer value and check zero       to i zero    gt  true nil to i zero    gt  true

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unless  nil  0  include  discount           end

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if  discount  0     0        end

[ruby] Checking if a variable is not nil and not zero in ruby

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