Bug #11406: Inconsistent behavior when creating a range of strings which end in an integer greater than 10

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: 2.2.2
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN

[iMIchael (Michael Martinez)]

Steps to Reproduce

In Ruby v2.2.2

1. Create a range of strings using 'foo1' up to 'foo9':

   ('foo1'..'foo9').to_a
   => ["foo1", "foo2", "foo3", "foo4", "foo5", "foo6", "foo7", "foo8", "foo9"]
   

   Observe the results are as we expect

2. Create a range of strings using 'foo1' up to 'foo10'

   ('foo1'..'foo10').to_a
   => ["foo1", "foo2","foo3","foo4","foo5", "foo6", "foo7", "foo8", "foo9", "fop0","fop1", "fop2", "fop3", "fop4", "fop5", "fop6", "fop7", "fop8", "fop9", "foq0", ....]
   

   Also:

   ('foo1'..'foo10').to_a.size
   => 4707939
   

   Observe that the output loops 1..9 about 523104 times (arbitrarily?)

Expected Results

The output in step 1 makes me expect for Ruby's range class to intelligently create ranges using a strings that include integers inside them. However this only seems to work for 1..9 ranges.

Actual Results

Inconsistent behavior for range creation.

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)

It's not inconsistent, but derived from the behavior of String#succ.

p "foo9".succ #=> "fop0"

And it ended with "zzzz9", or exceeds the length of "foo10".

I agree that the current behavior is less convenient in such cases.

[nobu (Nobuyoshi Nakada)]

https://github.com/nobu/ruby/tree/bug/11406-String%23upto-numeric-suffix

[Hanmac (Hans Mackowiak)]

i think that might break some things ... (it might break some applications)

like with "1.2.9".succ, i dont know if that still work

[nobu (Nobuyoshi Nakada)]

Hans Mackowiak wrote:

i think that might break some things ... (it might break some applications)

like with "1.2.9".succ, i dont know if that still work

String#succ isn't changed at all with my patch, but only String#upto when the receiver and the limit share common prefix and numerical suffixes.

The case affected is that alphabetical part is followed by the numerical suffix.
E.g.,

"1a2b9".upto("1a2b10").to_a

returns an empty array now, but ["1a2b9", "1a2b10"] with this patch.

In other words, your example has been handled specially already.

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed