# Upcase in 1.9.2-preview1

**URL:** <https://www.ruby-forum.com/t/upcase-in-1-9-2-preview1/172873>\
**Category:** Ruby\
**Created:** [July 29, 2009, 9:41am UTC](https://www.ruby-forum.com/t/upcase-in-1-9-2-preview1/172873 "2009-07-29T09:41:16Z")\
**Posts on this page:** 8\
**Page:** 1

<div class="post-metadata">

**Author:** ![stickstone](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/6f9a4e/32.png) [@stickstone](https://www.ruby-forum.com/u/stickstone)\
**Post date:** [July 29, 2009, 9:41am UTC](https://www.ruby-forum.com/t/upcase-in-1-9-2-preview1/172873/1 "2009-07-29T09:41:16Z")

</div>

Can someone confirm whether this is intentional or not?

> > RUBY\_DESCRIPTION  
> > =\> “ruby 1.9.2dev (2009-07-18 trunk 24186) [i686-linux]”
> 
> > s = “über”  
> > =\> “über”
> 
> > s.upcase  
> > =\> “üBER”

That is, a lower-case “ü” is not uppercased to “Ãœ”. And yet, “Ãœ” is  
detected as an upper-case letter:

> > “ÃœBER” =~ /[[:upper:]]/  
> > =\> 0
> 
> > “ÃœBER” =~ /[[:lower:]]/  
> > =\> nil

Thanks,

Brian.

---

<div class="post-metadata">

**Author:** ![stickstone](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/6f9a4e/32.png) [@stickstone](https://www.ruby-forum.com/u/stickstone)\
**Post date:** [July 29, 2009, 12:08pm UTC](https://www.ruby-forum.com/t/upcase-in-1-9-2-preview1/172873/2 "2009-07-29T12:08:53Z")

</div>

Hi,

Am Mittwoch, 29. Jul 2009, 16:43:36 +0900 schrieb Brian C.:

> detected as an upper-case letter:
> 
> > > “ÃœBER” =~ /[[:upper:]]/  
> > > =\> 0  
> > > “ÃœBER” =~ /[[:lower:]]/  
> > > =\> nil

By the way: I detected that there are some unicode characters where  
it is not clear whether they are up- or downcase. For example the  
DZ digraph has a version Dz that is the downcased version of DZ  
and the upcased version of dz.

U+01F1 DZ  
U+01F2 Dz  
U+01F3 dz

[Latin Extended-B - Wikipedia](http://en.wikipedia.org/wiki/Latin_Extended-B_unicode_block)

Vim’s ~ operator cycles through the three values. How will or  
should Ruby treat them?

Bertram

---

<div class="post-metadata">

**Author:** ![stickstone](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/6f9a4e/32.png) [@stickstone](https://www.ruby-forum.com/u/stickstone)\
**Post date:** [July 29, 2009, 12:21pm UTC](https://www.ruby-forum.com/t/upcase-in-1-9-2-preview1/172873/3 "2009-07-29T12:21:53Z")

</div>

Bertram S. wrote:

> Vim’s ~ operator cycles through the three values. How will or  
> should Ruby treat them?

I only have access to a slightly older 1.9.2 here, but:

> > RUBY\_DESCRIPTION  
> > =\> “ruby 1.9.2dev (2009-04-08 trunk 23158) [i686-linux]”
> 
> > ["\u01f1", “\u01f2”, “\u01f3”].each { |c| puts c =~ /[[:lower:]]/ }

0  
=\> [“DZ”, “Dz”, “dz”]

> > ["\u01f1", “\u01f2”, “\u01f3”].each { |c| puts c =~ /[[:upper:]]/ }  
> > 0

=\> [“DZ”, “Dz”, “dz”]

So the first is upper, the third is lower, and the second is neither 🙂

upcase/downcase does not affect any of them - but I’m not sure if the  
current behaviour is correct, which is why I started this thread.

---

<div class="post-metadata">

**Author:** ![stickstone](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/6f9a4e/32.png) [@stickstone](https://www.ruby-forum.com/u/stickstone)\
**Post date:** [July 29, 2009, 7:14pm UTC](https://www.ruby-forum.com/t/upcase-in-1-9-2-preview1/172873/4 "2009-07-29T19:14:30Z")

</div>

2009/7/29 Brian C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> That is: only ASCII characters (potentially encoded as UTF16 or  
> whatever) are eligible for case conversion.

Is it the correct approach?  
For me it’s very clear that the upcase version of á is Á.

---

<div class="post-metadata">

**Author:** ![stickstone](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/6f9a4e/32.png) [@stickstone](https://www.ruby-forum.com/u/stickstone)\
**Post date:** [July 29, 2009, 12:32pm UTC](https://www.ruby-forum.com/t/upcase-in-1-9-2-preview1/172873/5 "2009-07-29T12:32:37Z")

</div>

Brian C. wrote:

> Can someone confirm whether this is intentional or not?
> 
> > > s = “über”  
> > > =\> “über”
> > 
> > > s.upcase  
> > > =\> “üBER”

To answer my own question: looking at the source code, it looks like  
this _is_ intentional. From encoding.c:

int  
rb\_enc\_toupper(int c, rb\_encoding \*enc)  
{  
return  
(ONIGENC\_IS\_ASCII\_CODE©?ONIGENC\_ASCII\_CODE\_TO\_UPPER\_CASE©:©);  
}

int  
rb\_enc\_tolower(int c, rb\_encoding \*enc)  
{  
return  
(ONIGENC\_IS\_ASCII\_CODE©?ONIGENC\_ASCII\_CODE\_TO\_LOWER\_CASE©:©);  
}

That is: only ASCII characters (potentially encoded as UTF16 or  
whatever) are eligible for case conversion.

---

<div class="post-metadata">

**Author:** ![stickstone](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/6f9a4e/32.png) [@stickstone](https://www.ruby-forum.com/u/stickstone)\
**Post date:** [July 29, 2009, 7:28pm UTC](https://www.ruby-forum.com/t/upcase-in-1-9-2-preview1/172873/6 "2009-07-29T19:28:05Z")

</div>

Iñaki Baz C. wrote:

> 2009/7/29 Brian C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):
> 
> > That is: only ASCII characters (potentially encoded as UTF16 or  
> > whatever) are eligible for case conversion.
> 
> Is it the correct approach?  
> For me it’s very clear that the upcase version of á is Á.

There are perfectly clear Unicode rules for case conversion, but they  
are not simple. In some cases you need to replace one character by two  
(e.g. ß to SS)

There is a useful discussion about this from Python’s point of view  
here:

> **[convert Unicode to lower/uppercase? - Python](https://bytes.com/topic/python/answers/22883-convert-unicode-lower-uppercase)**
>
> convert Unicode to lower/uppercase?. Python Forums on Bytes.

---

<div class="post-metadata">

**Author:** ![stickstone](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/6f9a4e/32.png) [@stickstone](https://www.ruby-forum.com/u/stickstone)\
**Post date:** [July 29, 2009, 7:33pm UTC](https://www.ruby-forum.com/t/upcase-in-1-9-2-preview1/172873/7 "2009-07-29T19:33:50Z")

</div>

Hi,

In message “Re: upcase in 1.9.2-preview1”  
on Thu, 30 Jul 2009 02:13:41 +0900, Iñaki Baz C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
writes:

|\> That is: only ASCII characters (potentially encoded as UTF16 or  
|\> whatever) are eligible for case conversion.  
|  
|Is it the correct approach?  
|For me it’s very clear that the upcase version of á is Á.

But it’s locale dependent. In some languages, upper/lower case  
conversion is not one-to-one mapping.

```
          matz.

```

---

<div class="post-metadata">

**Author:** ![stickstone](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/6f9a4e/32.png) [@stickstone](https://www.ruby-forum.com/u/stickstone)\
**Post date:** [August 3, 2009, 2:54pm UTC](https://www.ruby-forum.com/t/upcase-in-1-9-2-preview1/172873/8 "2009-08-03T14:54:50Z")

</div>

Yukihiro M. wrote:

> But it’s locale dependent. In some languages, upper/lower case  
> conversion is not one-to-one mapping.

99% of the time it’s locale independant. I don’t follow this logic of  
“if we can’t make it work for everyone then it should stay broken for  
everyone”. Following the Unicode rules would fix uppercasing for 95% of  
those not using english. And for the 5% of those who have to deal with  
those asymmetric upper/lower case rules… well, they’d have to deal  
with it either way.

\*percentages above are guesswork