On Tuesday, 23 June 2015 at 17:11:57 UTC, Adam D. Ruppe wrote:
On Tuesday, 23 June 2015 at 16:14:59 UTC, Marc Schütz wrote:
But that's more an argument against putting anything _except_
the basic definitions into package.d, no? Then you can always
exclude the more specific stuff whenever you need it, and
those modules themselves can publicly import package.d.
What if you want the basic definitions alone to build something
off of?
If I want to write an image library that can share pixels with
your image library, I might import std.color just to get the
pixel format. I don't need the list of colors nor any
algorithms, I just want to share the basic type so our two
libraries can pass data back and forth.
So I write like
RGBA8[] readImage() {}
With the std.color functions, some other library can now take
that pixel array and convert it or whatever they need to do.
Great, you can use my thing pretty easily.
But I don't need any conversions myself. I don't do
transformations. I don't use named colors, blending functions,
or anything else. (Maybe my image format is extremely simple.)
So pulling the rest of the library would waste compile time and
binary space. Especially if a user wanted my extremely simple
image format exactly because they were short on time and space.
So ideally, my module would ONLY import std.color.basic_types
or something like that.... but alas, RGBA8 is defined in
package.d, so if I want it, whether I like it or not, I just
pulled half the std.color library....
which just pulled std.traits and std.typecons, which,
thankfully, didn't import anything else, but that's not the
case for so many Phobos modules.
This layout isn't bad today, the std.color in the PR is pretty
small and pretty lazy thanks to the templates and local imports
in them, but I still want to set a precedent in Phobos of
untangling the web of dependencies by moving as much
independent code as reasonably possible to independent modules.
Isn't this what selective imports are for? Admittedly it's not
quite as convenient, but it does let you choose exactly what you
want. You can even make a module that wraps a manually selected
set of imports, e.g. you do your own basic_types module.
In the end, if you have specific requirements, you have to be
specific.
