# Re: Hash order bug?

**URL:** <https://www.ruby-forum.com/t/re-hash-order-bug/99796>\
**Category:** Ruby\
**Created:** [July 25, 2006, 4:15pm UTC](https://www.ruby-forum.com/t/re-hash-order-bug/99796 "2006-07-25T16:15:14Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![BergerS\_Daniel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/bc8723/32.png) [@BergerS\_Daniel](https://www.ruby-forum.com/u/BergerS_Daniel)\
**Post date:** [July 25, 2006, 4:15pm UTC](https://www.ruby-forum.com/t/re-hash-order-bug/99796/1 "2006-07-25T16:15:14Z")

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> > > =\> false}  
> > > Now, i delete the foo function from the code (the foo
> > 
> > Hashes are unordered. If you need an ordered collection,  
> > you’ll need  
> > to use an array.
> > 
> > David
> 
> Oh my god, i didn’t know it, sorry. Is that a missing feature?

No, it’s just the way hashes behave. Note that there are ordered hash  
implementations on the RAA:

[http://raa.ruby-lang.org/project/orderedhash/](http://raa.ruby-lang.org/project/orderedhash/)

You can also use a Struct to get roughly the same effect.

Regards,

Dan

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**Author:** ![BergerS\_Daniel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/bc8723/32.png) [@BergerS\_Daniel](https://www.ruby-forum.com/u/BergerS_Daniel)\
**Post date:** [July 26, 2006, 2:39am UTC](https://www.ruby-forum.com/t/re-hash-order-bug/99796/2 "2006-07-26T02:39:29Z")

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Berger, Daniel wrote:

> No, it’s just the way hashes behave. Note that there are ordered hash  
> implementations on the RAA:
> 
> [http://raa.ruby-lang.org/project/orderedhash/](http://raa.ruby-lang.org/project/orderedhash/)
> 
> You can also use a Struct to get roughly the same effect.

In case anyone tries to refer me to these, I’ll point out that  
there are _three_ reasons I like a hash.

1. It indexes on an arbitrary value, not on an integer like  
an array.
2. It consists of explicit pairings of key and value.
3. There is a convenient sybtax for literals:  
{a=\>b, c=\>d, e=\>f}

Note that there are _no_ ordered hash solutions that preserve  
the third criterion.

Most would require me to do something like:

oh = OrdHash.new(a,b, c,d, e,f)

or

oh = OrdHash.new([a,b], [c,d], [e,f])

or something just as bad.

Don’t underestimate the importance of a convenient notation!  
What if arrays in Ruby were like arrays in C? In C, you can  
specify an array literal (barely) when you declare it; that’s  
about it.

Hal