What is the canonical way to trim a string in Ruby without creating a new string

Question

This is what I have now - which looks too verbose for the work it is doing    title          tokens Title  strip     tokens Title  if  tokens Title  nil    Assume tokens is a array obtained by splitting a CSV line  now the functions like strip  chomp  et  all return nil if the string was not modified   abc  strip         gt  nil   abc   strip       gt   abc    What is the Ruby way to say trim it if it contains extra leading or trailing spaces without creating copies   Gets uglier if I want to do tokens Title  chomp  strip

User · Answer

If you have either ruby 1 9 or activesupport  you can do simply   title   tokens Title  try  tap   amp  strip    This is really cool  as it leverages the  try and the  tap method  which are the most powerful functional constructs in ruby  in my opinion   An even cuter form  passing functions as symbols altogether    title   tokens Title  send  try   tap   amp  strip

User · Answer

I guess what you want is    title   tokens Title   title strip    The  strip  method will return nil if it didn t strip anything  and the variable itself if it was stripped   According to Ruby standards  a method suffixed with an exclamation mark changes the variable in place   Hope this helps   Update  This is output from irb to demonstrate    gt  gt   title    abc    gt   abc   gt  gt   title strip    gt  nil  gt  gt   title   gt   abc   gt  gt   title     abc     gt    abc    gt  gt   title strip    gt   abc   gt  gt   title   gt   abc

User · Answer

I think your example is a sensible approach  although you could simplify it slightly as    title   tokens Title  strip     tokens Title  if tokens Title    Alternative you could put it on two lines    title   tokens Title         title strip

User · Answer

My way    gt    title     abc    strip     gt   abc    gt   title    gt   abc

User · Answer

If you want to use another method after you need something like this     str strip    str   split        This way you can strip and still do something after

User · Answer

There s no need to both strip and chomp as strip will also remove trailing carriage returns - unless you ve changed the default record separator and that s what you re chomping   Olly s answer already has the canonical way of doing this in Ruby  though if you find yourself doing this a lot you could always define a method for it   def strip or self  str    str strip     str end   Giving    title   strip or self  tokens Title   if tokens Title    Also keep in mind that the if statement will prevent  title from being assigned if the token is nil  which will result in it keeping its previous value  If you want or don t mind  title always being assigned you can move the check into the method and further reduce duplication   def strip or self  str    str strip     str if str end   As an alternative  if you re feeling adventurous you can define a method on String itself   class String   def strip or self      strip     self   end end   Giving one of    title   tokens Title  strip or self  if tokens Title    title   tokens Title   amp  amp  tokens Title  strip or self

User · Answer

If you are using Ruby on Rails there is a squish   gt   title     abc      gt    abc      gt   title squish    gt   abc   gt   title    gt    abc     gt   title squish     gt   abc   gt   title    gt   abc     If you are using just Ruby you want to use strip  Herein lies the gotcha   in your case you want to use strip without the bang    while strip  certainly does return nil if there was no action it still updates the variable so strip  cannot be used inline  If you want to use strip inline you can use the version without the bang    strip  using multi line approach   gt  tokens  Title       abc      gt    abc    gt  tokens  Title   strip     gt   abc   gt   title   tokens  Title      gt   abc    strip single line approach    YOUR ANSWER   gt  tokens  Title       abc      gt    abc    gt   title   tokens  Title   strip if tokens  Title   present     gt   abc

User · Answer

Btw  now ruby already supports just strip without       Compare   p  abc  strip       abc   strip     false  because  abc  strip  will return nil p  abc  strip      abc   strip      true   Also it s impossible to strip without duplicates  See sources in string c    static VALUE rb str strip VALUE str        str   rb str dup str       rb str strip bang str       return str      ruby 1 9 3p0  2011-10-30   i386-mingw32   Update 1  As I see now -- it was created in 1999 year  see rev  372 in SVN     Update2  strip  will not create duplicates     both in 1 9 x  2 x and trunk versions

User · Answer

title   tokens Title  strip     tokens Title    It s entirely possible i m not understanding the topic  but wouldn t this do what you need     success   strip      rescue     gt   success   failure  strip      rescue     gt   rescue

[ruby] What is the canonical way to trim a string in Ruby without creating a new string?

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