On Sunday, 24 July 2016 at 02:45:57 UTC, rikki cattermole wrote:
On 24/07/2016 2:28 PM, Rufus Smith wrote:
NM, ignore. Seems it was something else going on. Although, if
you know
how how dmd resolves this stuff exactly, it would be nice to
know. Does
it just use the module names regardless of path or does the
path where
the module is located have any play(assuming they are properly
passed to
the compiler).
My understanding is this:
1. For each file passed, use supplied module name
2. If an import is unknown look at each of the directories
passed via -I and find it based upon a/b/c.d for module a.b.c;
3. For each file passed, if an import is unknown try to guess
based upon paths
Of course rdmd adds another level of behavior on top and is
mostly based upon the third one.
If in doubt, try using dub. It can show you all this without
looking at code ;)
The thing I remember being confused about was that you had to use
the -I option to specify what root level module directories you
want to import from AND in the file that is being imported you
have to explicitly put the module name at the top of the file. In
both cases, the error message you get usually doesn't make it
obvious what you've done wrong. I think if you forget to put the
module name at the top of the file you'll end up with a very
generic message like "can't import module y".
Note that this only takes care of compilation, and doesn't
include how to make sure linking works. If you need more info on
that let me know.
For your example:
foo
bar
x
baz
y
baz.d(package)
If you had a module inside the y directory, you would need to
include the root level path for the y package like this:
foo/bar/x> dmd main.d -I../baz
Then each module you want from y, should be imported explicitly
like this:
import y.coollib;
import y.awesomeutil;
If you want to import multiple files from y using "import y;",
then there needs to be a package.d file inside the y directory:
foo/baz/y/package.d:
public import y.coollib;
public import y.awesomeutil;
The library may or may not have a package.d file. If it does
not, then each module is probably meant to be imported
independently.
Also if you really need to know what's going on, you can find the
source code that finds imports in dmd here(I just happen to know
this because I just made a PR modifying this code):
https://github.com/dlang/dmd/blob/master/src/dmodule.d#L48
Hope this helps. I do remember being confused about how all this
worked a few years ago but now it all makes sense. Not sure if
this information is easy to find or not, if it's not, it should
be added somewhere.
