Re: [boost] [mpl]suggested additioninvault/cppljevans/mpl/child_i_depth_j.zip

From: Jonathan Turkanis (technews_at_[hidden])
Date: 2005-08-04 01:01:00

Larry Evans wrote:
> Jonathan Turkanis wrote:
>> Larry Evans wrote:
>>
>>> child_i_depth_j allows the traversal of a tree of applications.
>>> It's useful for accessing, for example, the i-th superclass of
>>> the results of mpl/fold, as demonstrated by the test file:

>>> Could this be added to mpl?  Is there something I could do
>>> to facilitate this addition?
>>
>>
>> Writing some documentation might help. For instance, what is an
>> application? You
>
>  >>accessing, for example, the i-th superclass of
>  >>the results of mpl/fold,
>
> For example, I've used fold to calculate the size of both a tuple and
> variant.  In order to access the offset of the j-th element of the
> tuple, I can use child_i_depth_j.  I've also used it to access the
> j-th acceptor method in a class derived the variant.  For a variant
> of n elements, there are n acceptor methods, one for each element.
> They are generated also with fold.  Given that the value of the
> variant's tag is a run-time value, I need to create a vector
> of methods and access the appropriate acceptor method.... Oh it's
> getting to complicated to explain. I'll just upload it to the vault.

What I meant is that you should write a detailed decription of what it does: how
many arguments it takes, what properties they must have, what nested types the
result has, etc.

Jonathan