On 13/09/2018 11:54 PM, Jonathan Marler wrote:
"Selective imports" limit the symbols imported from a module by
providing a list of all the symbols to include:
import std.stdio : writeln, writefln;
The complement of this would be a "Filtered import", meaning, import all
the symbols except the ones in the provided list. I imagine the syntax
would look something like:
import std.stdio ~ writeln, writefln;
To provide a use case for this, say you have a module that uses a fair
amount of symbols from `std.file` but you want to make sure that all
calls to `chdir` are logged. Using a filtered import would allow you to
exclude `chdir` from being available globally so you could create a
wrapper that all code is forced to go through.
import std.stdio;
import std.file ~ chdir;
void chdir(R)(R path)
{
writefln("chdir '%s'", path);
from!"std.file".chdir(path);
}
It's an interesting variation on D's current repertoire of import
semantics. Possibly worth consideration as an addition to the language.
Grammar Changes:
-----------------------------------------------------
ImportBindings: (existing rule)
Import : ImportBindList (existing rule)
Import ~ ImportExcludeList (new rule)
ImportExcludeList: (new rule)
Identifier, ImportExcludeList (new rule)
-----------------------------------------------------
import std.stdio;
import std.file;
void chdir(R)(R path) {
writeln("changing dir to ", path);
std.file.chdir(path);
}
void main()
{
chdir("/tmp");
}
