envy for "Writing Go Packages"

[Andrei Alexandrescu]

Michel Fortin wrote:
> On 2010-05-07 13:55:34 -0400, Walter Bright <newshound1 at digitalmars.com> 
> said:
> 
>> Source code could look something like:
>>
>>      import http.d_repository.foo.version1_23;
>>
>> and the compiler could interpret "http" as meaning the rest is an 
>> internet url, foo is the package name, and version1_23 is the 
>> particular version of it.
> 
> So now, each time a new version of a library pops up you need to 
> search-replace the version number for all your source code, and source 
> code of other library you depend on? This is insane.

Not at all. Some builds want to peg the code against a specific version, 
so they encode that in the path. Some others may just want to use the 
latest, so they'd import http.d_repository.foo.current. On the server, 
current is always aliased to the latest.

This scheme is used everywhere on Unix.

> The version number shouldn't be there, except perhaps if it's a 'major' 
> version number full of breaking changes.

When I delivered my book, my publisher asked me to send them all LaTeX 
packages I used. I replied, "they're the system-provided packages coming 
with LiveTeX x.y.z". They insisted they need the exact files so they 
have them. It's not at all uncommon (albeit sad) that software is built 
for a very specific version of some software. My employer has huge issues m

> Also, putting in the source code the location or protocol to fetch the 
> repository isn't much better. There's a reason we have a module import 
> path: so that finding external code depends on compile-time 
> configuration, not on the actual code you build.

That's a good point. At a minimum, there should be the possibility to 
define aliases like this:

alias http.erdani.com.tdpl.code tdpl;
...
import tdpl.stuff;

Then the alias definition becomes a unique point of maintenance. 
Unfortunately something like that doesn't currently work, so if the 
online modules feature is introduced, we need to introduce such aliases 
as well.

> Allowing URLs in the import path might be an interesting idea though.

Yah. Unfortunately other languages don't have it so it's difficult to 
learn from others' experience.


Andrei