Phobos/Tango Unification Plans

[Don]

Sean Kelly wrote:
> Bruno Medeiros wrote:
>> Don wrote:
>>> Benji Smith wrote:
>>>> I was just looking through bearophile's library (which is based on 
>>>> Phobos) and thinking about how it's too bad that I can't use it 
>>>> because my code is all based on Tango.
>>>>
>>>> I know there are plans currently in the works to implement a 
>>>> compatible runtime layer, via Sean's druntime project. And it'll be 
>>>> a breath of fresh air to get rid of the basic incompatibilities in 
>>>> the two runtimes.
>>>>
>>>> But if that's all that happens, it'll still leave an undesirable 
>>>> situation, since all the other userland stuff will be incompatible.
>>>>
>>>> Eventually, any significantly complex project is likely to have some 
>>>> dependent libraries built on top of both Phobos and Tango. At the 
>>>> very least, string-processing routines from both libraries will get 
>>>> compiled into the final executable.
>>>>
>>>> Not only will that result in duplication of functionality (and code 
>>>> bloat), but it'll also mean a bunch of bit-twiddling whenever 
>>>> sending a Tango type into a Phobos-dependent library function (and 
>>>> vice versa).
>>>>
>>>> Are there any plans in the works to mitigate that problem? Like, 
>>>> perhaps, negotiating a common API so that at least the names and 
>>>> argument types are the same in both libraries?
>>>>
>>>> I'm sure the two libraries will always include different subsets of 
>>>> functionality, but whenever they implement the same basic features, 
>>>> it'd be great if they used a compatible API.
>>>>
>>>> --benji
>>>
>>>
>>> That could have some difficult aspects, but here's an uncomplicated 
>>> second step: The math libraries for Tango and Phobos aren't merely 
>>> compatible, they are THE SAME! They are a cut-and-paste of each 
>>> other, with a couple of trivial name changes.
>>> There are no licensing issues or personality clashes to worry about 
>>> -- I've written most of both of them. They have no dependencies on 
>>> anything else in either Phobos or Tango. I have write access to 
>>> repositories of both Phobos and Tango.
>>> YET -- there are two bodies of code! This is absolutely ridiculous, 
>>> and it's driving me mad.
>>>
>>> How can we turn this into ONE body of code?
>>> It will only be possible if there is a namespace which is present in 
>>> both Tango and Phobos. There are exactly three ways in which this can 
>>> be done:
>>> Either
>>> (1) Tango needs to include part of the std namespace,
>>> (2) Phobos needs to include part of the tango namespace, or
>>> (3) Both need to start including a new namespace which is common to 
>>> both.
>>>
>>> Of these options, I think (2) is the least natural. For (1) to work, 
>>> the modules invoved would need to be clearly designated as common.
>>
>> I don't get it. Why is it that "For (1) to work, the modules invoved 
>> would need to be clearly designated as common." ? Since Tango will 
>> become compatible with Phobos (same runtime), can't Tango just 
>> use/depend-on some of Phobos functionality?
> 
> I believe Tango aims to continue being separately distributable from 
> Phobos, so this isn't likely to happen.  Another option would be for the 
> math package to live in a separate project that's bundled with both 
> libraries, though I don't know how either team feels about the logistics 
> of such an arrangement.

That's option (3).