Re: [boost] [TTI] Review for The Type Traits Introspection library by Edward Diener **extended**

Subject: Re: [boost] [TTI] Review for The Type Traits Introspection library by Edward Diener **extended**
From: Edward Diener (eldiener_at_[hidden])
Date: 2011-07-18 19:49:32

On 7/18/2011 1:34 PM, Jeffrey Lee Hellrung, Jr. wrote:
> On Sun, Jul 17, 2011 at 3:18 PM, Edward Diener<eldiener_at_[hidden]>wrote:
>
>> On 7/17/2011 4:15 PM, Jeffrey Lee Hellrung, Jr. wrote:
>>
>>> On Sun, Jul 17, 2011 at 12:35 PM, Edward Diener<eldiener_at_[hidden]**
>>>> wrote:
>>>
>>>   On 7/17/2011 2:22 PM, Jeffrey Lee Hellrung, Jr. wrote:
>>>>
>>>>   Well, if the naming scheme is simple (I think it is), I don't think we
>>>>> have
>>>>> to worry about the metafunction provider nor the metafunction user not
>>>>> understanding the naming scheme.  Have users been requesting these GEN
>>>>> macros?  Are the GEN macros targeted toward the metafunction provider
>>>>> (who
>>>>> should know what identifiers he's injecting into the namespace) or the
>>>>> metafunction user (who will need to read documentation either way to get
>>>>> the
>>>>> name of the metafunction)?  I don't really see the point, and I now
>>>>> refer
>>>>> you to my comment about "less is more" at the top.
>>>>>
>>>>>
>>>> The GEN macros are targeted at the metafunction user. If people really
>>>> feel
>>>> it is easier reading the documentation and looking at the way that
>>>> metafunction names are generated than to just repeat the metafunction
>>>> macro,
>>>> add _GEN to the end, and pass it element name to automatically generate
>>>> the
>>>> metafunction name, I may remove the GEN macros. I still think that using
>>>> the
>>>> equivalent GEN macro for each metafunction macro is a nice and easy way
>>>> to
>>>> get the refer to the name of the metafunction for each metafunction
>>>> macro.
>>>>
>>>>
>>> They'd have to read the documentation to figure out how to use the GEN
>>> macros, too :)  Also "reading the documentation and looking at the way
>>> that
>>> metafunction names are generated" is 13 words worth work, while "repeat
>>> the
>>> metafunction macro, add _GEN to the end, and pass it element name to
>>> automatically generate the metafunction name" is 20 words worth work, so
>>> the
>>> former is by far easier than the latter :)
>>>
>>
>> I thought it would be easier, given let's say macro
>>
>> BOOST_TTI_HAS_STATIC_MEMBER_**FUNCTION(name),
>>
>> to refer to the metafunction name as
>>
>> BOOST_TTI_HAS_STATIC_MEMBER_**FUNCTION_GEN(name)
>>
>> than to remember it is:
>>
>> 'has_static_member_function_**name'.
>>
>> I admit I can be wrong about this but I really, really do not see what harm
>> those GEN macros can cause for those who want to use them instead.
>>
>
> If the GEN macros are primarily for the metafunction *users*, you're really
> taking up the burden that should be carried by the metafunction
> *providers*.

By metafunction users I mean programmers using TTI in their 
metaprogramming along with MPL, type traits, and such.

>  It would be the metafunction provider's job to ensure their
> users know their API.  The metafunction user may not even know or care about
> the existence of the TTI library (they should, of course, but I think it's a
> reasonable possibility).
>
> And, sorry, I don't see how one is easier to remember than the other :/
> Just take the part of the macro after BOOST_TTI_, lowercase it, and append
> _'name'.

Actually in one case this is currently not followed ( he looks up aghast 
<g> ). The current BOOST_TTI_VM_HAS_TEMPLATE_CHECK_PARAMS generates the 
same metafunction name as BOOST_TTI_HAS_TEMPLATE_CHECK_PARAMS, which is 
'has_template_check_params_' instead of 'vm_has_template_check_params_'. 
My reasoning for this was that the non-variadic macro and variadic macro 
version did the same thing.

But this anomaly will go away with the new combined BOOST_TTI_TEMPLATE 
macro.

>  I mean, I thought one of the points about the automatic name
> generation is so people *don't* have to think about the name of the
> metafunction...

True.

>
> You're giving users 2 different ways to do the same thing.  One way you
> don't really have any choice to give (the user can just use the name of the
> metafunction directly), and I just don't see the other (the GEN macros)
> offering any compelling advantages.  I think this is laying the groundwork
> for confusion.

I acknowledge I provide two ways, but I do not think confusion is involved.

Even the process of taking a macro name, dropping BOOST_TTI_, 
lowercasing the rest, and adding _name may seem laborious to some to 
remember. Can't you conceive that it might be easier for the end-user to 
use the equivalent _GEN macro. I found it easier when creating the 
examples so surely there are others who might like that idea.