Re: [Yaml-core] YAC#24 - Big warning if Mixing Tabs and Spaces

[Brian I. <in...@tt...>]

On 07/03/02 09:19 -0500, Clark C . Evans wrote:
> Ok.  I have a refinement!
> 
>    The _only_ tab/space mixing policy is TAB:8, aka TASTY.
>    YAML emitters then either use tabs or spaces depending on 
>    the user's choice and _never_ produce YAML that mixes tabs
>    and spaces.   If tabs and spaces are _mixed_ in an input 
>    file, the parser must produce this warning:

I would prefer that YAML emitters never emit tabs.

>      WARNING: This file's indentation mixed tabs and spaces.  Mixing
>      of tabs and spaces may not be portable since different editors
>      may have different policies.  In a YAML file, tabs are mixed with
>      spaces by treating a tab as 1..8 spaces such that the resulting
>      column is evenly divisible by 8 (standard unix treatment).a
> 
>    The goal of this warning is to irritate the user enough that they
>    stop mixing tabs and spaces, thus it should not be suppressable else
>    we will cause ourselves a big headache down the road.  Further, 
>    We then put up a big warning sign on our website and FAQ describing
>    how TABs and SPACE mixing can cause compatibility problems with
>    various editors.
> 
> IMHO, this seems the simplest.  Our problem isn't with TABS, it's
> with the Mixing of TABS with SPACEs.

Clark. How many times do I need to repeat myself? We *can't* encode YAML with
just TABS. That means we must either have mixing or disallow tabs. 

The reason is because of our explicit multiline indentation notation:

   foo: |3 
   bar: ]\5 
   
etc. This is in terms of spaces not TABs.

Cheers, Brian