[fpc-devel] for-in-index loop

[Jeppe Græsdal Johansen]

Den 23-01-2013 00:54, vrt277 skrev:
> Hi FPC team,
>
> There is good proposed extension of for-in loop on fpc wiki: get 
> enumerator Position if available 
> <http://wiki.freepascal.org/for-in_loop#Proposed_extensions>. From my 
> point of view it's essential part of iterators. Especially for data 
> structures which store pairs of key and value associated with key.
>
> I want to implement this extension. Moreover I started implementation 
> to explore fpc internals. Current /(not finished)/ result available on 
> github. 
> <https://github.com/vkevroletin/freepascal/tree/key-value-iterator>
>
> My motivation is simple: I'm a student. My teacher is Alexander S. 
> Klenin who should be well known to fp? developers. And I want to 
> implement some feature of fpc as my graduate work. Through improvement 
> of for-in loop is not enough for good graduate work but it is good 
> initial step towards other big contribution.
>
> So is get enumerator Position if available 
> <http://wiki.freepascal.org/for-in_loop#Proposed_extensions> good idea?
>
> Thanks,
> Vasiliy Kevroletin
>
> P.S. links for people who dislike computer mouse:
>
> proposed extension - 
> http://wiki.freepascal.org/for-in_loop#Proposed_extensions
> my branch on github - 
> https://github.com/vkevroletin/freepascal/tree/key-value-iterator

I think the idea is good if the feature is implemented as "optional".

That way:
- If the enumerator class implements a CurrentIndex method then the for 
loop can have an index variable.
- If not then the for loop can only behave as current for in loops.
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