Split with negative limit

ruby-talk
1

Word o' warning. I just put this comment in a program:

  lines = self.split("\n",-1) # boy oh boy was that -1 a pain to figure out!

All told I probably wasted half of my day trying to figure this out because it
was causing another part of the program to act oddly (which I still don't
quite get but nonetheless), thus digusing the real issue.

This is VERY unintuitive. The value itself doesn't even /do/ anything when the
limit is negative. Moreover, is the default of supressing null fields really
best? Recommend improvement something like:

  def split( pattern=$; , supres_null=false , limit=nil )

No negative number trick.

Thanks,
T.

2

Word o' warning. I just put this comment in a program:

  lines = self.split("\n",-1) # boy oh boy was that -1 a pain to figure out!

???

  str = "one\n\ntwo\n\nthree"
    ==>"one\n\ntwo\n\nthree"
  str.split("\n")
    ==>["one", "", "two", "", "three"]
  str.split("\n",-1)
    ==>["one", "", "two", "", "three"]
  RUBY_VERSION
    ==>"1.9.0"

What did you gain by adding the -1 in? I tried this same thing using
ruby 1.6.8, got the same results.

Null field filtering is normally only done when no arguments are
passed, or with the special case " " argument.

···

On Sun, 10 Oct 2004 13:18:48 +0900, trans. (T. Onoma) <transami@runbox.com> wrote:

All told I probably wasted half of my day trying to figure this out because it
was causing another part of the program to act oddly (which I still don't
quite get but nonetheless), thus digusing the real issue.

This is VERY unintuitive. The value itself doesn't even /do/ anything when the
limit is negative. Moreover, is the default of supressing null fields really
best? Recommend improvement something like:

  def split( pattern=$; , supres_null=false , limit=nil )

No negative number trick.

Thanks,
T.

3

It's taken from Perl. See 'man perlfunc':

       split /PATTERN/,EXPR,LIMIT
...
               If LIMIT is specified and positive, splits into no more than
               that many fields (though it may split into fewer). If LIMIT is
               unspecified or zero, trailing null fields are stripped (which
               potential users of "pop" would do well to remember). If LIMIT
               is negative, it is treated as if an arbitrarily large LIMIT had
               been specified.

Perhaps in the early days, Ruby being similar to Perl was considered a good
thing :slight_smile:

Regards,

Brian.

···

On Sun, Oct 10, 2004 at 01:18:48PM +0900, trans. (T. Onoma) wrote:

Word o' warning. I just put this comment in a program:

  lines = self.split("\n",-1) # boy oh boy was that -1 a pain to figure out!

All told I probably wasted half of my day trying to figure this out because it
was causing another part of the program to act oddly (which I still don't
quite get but nonetheless), thus digusing the real issue.

This is VERY unintuitive.

4

> Word o' warning. I just put this comment in a program:
>
> lines = self.split("\n",-1) # boy oh boy was that -1 a pain to figure
> out!

???

  str = "one\n\ntwo\n\nthree"
    ==>"one\n\ntwo\n\nthree"
  str.split("\n")
    ==>["one", "", "two", "", "three"]
  str.split("\n",-1)
    ==>["one", "", "two", "", "three"]
  RUBY_VERSION
    ==>"1.9.0"

What did you gain by adding the -1 in? I tried this same thing using
ruby 1.6.8, got the same results.

irb(main):001:0> str = "one\n\ntwo\n\nthree\n\n"
=> "one\n\ntwo\n\nthree\n\n"
irb(main):002:0> str.split("\n")
=> ["one", "", "two", "", "three"]
irb(main):003:0> str.split("\n",-1)
=> ["one", "", "two", "", "three", "", ""]

Null field filtering is normally only done when no arguments are
passed, or with the special case " " argument.

Without the -1 I was loosing all my remaining blank lines.

(using 1.8.2)

T.

···

On Sunday 10 October 2004 12:54 am, Mark Hubbart wrote:

On Sun, 10 Oct 2004 13:18:48 +0900, trans. (T. Onoma) > > <transami@runbox.com> wrote: