ldc and gdc

[Marco Leise]

Am 05.08.2011, 08:35 Uhr, schrieb Jacob Carlborg <doob at me.com>:

> On 2011-08-04 22:37, Marco Leise wrote:
>> Am 04.08.2011, 19:34 Uhr, schrieb Jonathan M Davis  
>> <jmdavisProg at gmx.com>:
>>
>>>> By the way... the druntime and phobos patches for LDC - are they
>>>> applicable to GDC and DMD as well? I'm asking because I could imagine
>>>> installing druntime, phobos, DMD, GDC and LDC and all three compilers
>>>> would use the same installation of the standard library.
>>>
>>> They _can't_ all use the same installations. At minimum, druntime must  
>>> be
>>> different for each of them. That's expected and by design. Whether  
>>> Phobos
>>> needs to be different for each or not as far as source goes, I don't  
>>> know
>>> (hopefully not, but there might be a reason why it has to). But since  
>>> the
>>> compiled library includes both druntime and Phobos, that can't be  
>>> shared.
>>>
>>> - Jonathan M Davis
>>
>> Thank you for the clarification. My impression was that druntime was
>> created to make it possible to use either phobos or tango. If the
>> compiled library includes both (with which compiler anyway? both GDC and
>> LDC?) I figure that I could not install any two of the three compilers
>> in their default locations on Linux, correct? If I take the time to
>> create packages for Gentoo for the alternative compilers that is good to
>> know. Symlinks and altered library names for druntime/phobos would be
>> required. But with a mix of DMD1, DMD2, GDC, LDC, Phobos and Tango
>> things could become messy :p
>
> In the future, DVM could be used for this. DVM lets you easily install  
> different versions of a D compiler and switch among them. Although it  
> currently only supports DMD. DVM: https://bitbucket.org/doob/dvm

I have noticed DVM around.
The situation on Gentoo is typically that when there are different  
versions of the same package, that can be installed in different 'slots'.  
A dependency of these packages is a control file for eselect, a tool to  
switch between the currently active implementation (OpenJDK, Sun Java,  
...), package version (boost) and several other system configuration  
options. 'python' for example ends up as a symlink to either python2.7 or  
python3.1 and there are corresponding directory names for the libraries.  
It would be ideal if dmd was a symlink to either dmd1 or dmd2 and they  
would both use a separate dmd.conf. But since the source code is available  
for a while now that should be easy to make possible.
I have never used DVM, but I imagine it works like Maven or the Eclipse  
updater. So it would download precompiled compilers and libraries into the  
user's home directory, right? With Gentoo being a source distribution it  
is usually avoided to download binaries from the internet so I guess DVM  
would be one of two options to install D compilers on Gentoo. The  
difference in usage would be like this for an installation:
dvm: "dvm install 1.068"
portage: "emerge =dmd-1.068"
and this for setting the system-wide default compiler:
dvm use 1.068 -d
eselect dmd set dmd1
Granted, the portage version would only allow one dmd 1 compiler to be  
installed at a time, but that is ok for most users. I guess in theory  
there could even be slots for every single release of dmd. This is already  
done for Boost and automake in practice (with major revisions). OTOH there  
is no option to set the compiler for the current shell, but maybe "export  
DMD=dmd1", "make posix.mak" should work.