It's only a reformulation of Ulises comment but I would say:
1) abstract away how the data is accessed
2) introduce change one function at a time by swapping the past accessor
with the new accessor (really it is like a getter/setter)
3) if you have final consumer(s) you might need to introduce a
datastructure (a map?) stating which id should be accessed with the new
implementation of the accessor
Bertrand
Le jeudi 22 mai 2014 10:21:30 UTC+2, Ulises a écrit :
>
> How are you accessing the data?
>
> I suppose that if you were accessing (maybe you are) the data via helper
> functions, that's where most of the refactoring should happen.
>
>
> On 22 May 2014 09:17, Jakub Holy <jakub...@iterate.no <javascript:>>wrote:
>
>> I have a nested data structure, used by a bunch of functions that presume
>> knowledge of its structure, and I wonder how to change a part of the
>> structure in a safe way, preferably in small incremental steps, rather than
>> having my code broken until I update all the functions and tests for the
>> new structure. I believe many of you must have experiences with this, would
>> you care to share some tips?
>>
>> The data structure is first built incrementally and the collected data is
>> later summarized. Instead of replacing the raw data with their summary, I
>> want to keep both, so I want to wrap the data with a map; i.e. from:
>> { <id> [ data...] } ;; later replaced with {<id> summary}
>> to
>> {<id> {:data [data...], :summary ...}
>>
>> I have a number of functions operating on the structure and tests for
>> those functions (with test data that also need to be updated w.r.t. the
>> refactoring).
>>
>> When I change one of the functions to produce the new data structure
>> (i.e. data wrapped in a map instead of the data itself), everything else
>> breaks. So I fix some tests and another function and get even more
>> failures. This does not feel as a good way to do it as I prefer to have
>> limited
>> red <http://www.infoq.com/presentations/The-Limited-Red-Society> and am
>> fond of parallel
>> change<http://theholyjava.wordpress.com/wiki/development/parallel-design-parallel-change/>for
>> that reason.
>>
>> Ideally, I would have an automated refactoring or the possibility to wrap
>> the data in some kind of a two-faced proxy that could behave both as a
>> vector (towards the old code) or as a map containing the vector (towards
>> the updated code) [some thing like lenses/cursor?!]. I haven't either so I
>> guess the only option remaining is a well-controlled process of updating
>> the structure and code. Any advice?
>>
>> Thank you! /Jakub
>> --
>> *Forget software. Strive to make an impact, deliver a valuable change.*
>>
>> *(**Vær så snill og hjelp meg med å forbedre norsken **min –** skriftlig
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>>
>> Jakub Holy
>> Solutions Engineer | +47 966 23 666
>> Iterate AS | www.iterate.no
>> The Lean Software Development Consultancy
>> - http://theholyjava.wordpress.com/ -
>>
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