On Thu, Dec 13, 2012 at 3:11 AM, Igor Stasenko <siguctua@gmail.com> wrote:

On 13 December 2012 03:08, Igor Stasenko <siguctua@gmail.com> wrote:
> On 11 December 2012 20:33, Ciprian Teodorov <ciprian.teodorov@gmail.com> wrote:
>> Hi guys,
>>
>> today I have commited to the NativeBoost repository a new core class, the
>> NBExternalEnumerationType,
>> which reifies the enum declarations in C and offers a nice interface
>> (especially in terms of debug/inspect).
>>
>> To use it just subclass the NBExternalEnumeration and add an #enumDecl
>> method to the class side such as:
>>
>> NBExternalEnumeration subclass: #NBTestEnumeration
>> instanceVariableNames: ''
>> classVariableNames: ''
>> poolDictionaries: ''
>> category: 'NativeBoost-Tests'
>>
>> NBTestEnumeration class>>enumDecl
>> ^ {(#AAA -> 1).
>> (#BBB -> 2).
>> (#CCC -> 3).
>> (#DDD -> 2400)} asDictionary
>>
> just one comment: imo, it would be better to not force users to
> remember that they should use
> complicated syntax in this method.
>
> i propose following syntax:
>
> NBTestEnumeration class>>enumDecl
> �^ #(
> � #AAA 1
> � #BBB -> 2
> � #CCC -> 3
> � #DDD -> 2400
> � )
>

oops, of course it should be just pairs, e.g.:
#( A 1 B 2 C 3)

Yep this is a good idea for most cases so I'll integrate it. But there are those cases where your enum has many items (more than the number of literals we can have in a method), and I think in those cases having the user give us a prebuilt dictionary is better.
> then you can have
>
> NBTestEnumeration class>>initializeEnum
>
> � dict := Dictionary newFromPairs: self enumDecl
> � �.....
>
> then #initialize should just do 'self initializeEnum'
>
>
>
>> DO NOT FORGET to call the #initialize method on your class. The rest is
>> automatically done ;)
>>
>> You can use your new enum in two ways:
>>
>> add it to a client class poolDictionaries list (see �#NBExternalEnumTests
>> for an example), and then just write CCC in your code -- CCC here is an item
>> of your enum
>> or you can send the name of an item to your class --- NBTestEnumeration DDD
>>
>> The NBExternalEnumeration implements �(instance and class) some more API
>> methods like:
>>
>> #itemAt: retrieves the item having a specific value �--- NBTestEnumeration
>> itemAt: 2
>> #includes: checks the existence of a specific item in the enum ---
>> NBTestEnumeration includes: #AAA
>>
>> Having this already gives us a nice interface to working with enums. Now I
>> plan to improve a little bit on performance and usage scenarios:
>>
>> the possibility to accept smalltalk integers as valid input/output for
>> functions(or callbacks) that use enums as arguments/return.
>> support the different representation types for the enum values (int/uint)
>>
>
> to my thinking, it not worth implementing separate type converter for enums..
> just put a note that if people would like to deal nicely with enums
> returned by function(s),
> they should use a converter , something like that:
>
> enumValue := MyEnumeration fromInteger: (self callSomeFunctionReturningInt)

This is a good idea too.�

>
> then this method can implement converting from int->enum object,
> as well as do a range checking etc.
> in same way, if people want to use 'enumValue' for passing it as
> parameter to external function,
> they should not pass it directly , but use 'enumValue value'
>
> In general, it would be cool to have good 'enum type' converter..
> (despite that i will never use it,
> because to my taste its not really worth it, and i can live with
> integers and in most cases you hide such low-level details from
> end-user anyways ;))
> but for those, who want more clarity and better structure in their
> code, of course, they can use it .
>

I do not completely agree with you on this one (but you already now it). The thing is that if we use integers then the user will have to constantly ask which enum value should I pass here... If you want that you can always have it by declaring your function signature as #(void fct(int anEnumValue)) and then call it with MyEnum DDD value (that's fine). Having an enum type converter is very good for documenting the argument types (and automatically checking them). So I think this should be the user choice. Moreover, I'm for incremental development (and learning) so the way I see it is: When you first implement the ffi wrapper just try to be as precise as you can be, then after your library binding is done you can change some declarations to use more 'low level types' (the underlying representation) for speed reasons mainly (if it ever comes to that).�

But at the end I think we should give our users options, which will help them make decisions based on their particular needs, not based on our "gut" feeling ;)

>
>> So that will be for now. Feel free to try it out and send me any comments
>> and/or improvement ideas, It will be my pleasure to improve it.
>> Cheers,
>> --
>> Dr. Ciprian TEODOROV
>> Ing�nieur D�veloppement CAO
>>
>> t�l : 06 08 54 73 48
>> mail : ciprian.teodorov@gmail.com
>> www.teodorov.ro
>
>
>
> --
> Best regards,
> Igor Stasenko.

--
Best regards,
Igor Stasenko.