Re: Keeping imports clean

[Andrej Mitrovic]

On 4/2/12, James Miller  wrote:
> So in short, it isn't relevant at all.

It is relevant to build times. Compare the build times of this:

import std.algorithm;
import std.array;
import std.conv;
import std.file;
import std.string;
import std.stdio;
import std.typetuple;
import std.typecons;
import std.traits;
import std.range;

void main() { }

With this:
void main() { }

First:
$ timeit dmd test.d
Elapsed Time: 0:00:00.296

Second:
$ timeit dmd test.d
Elapsed Time: 0:00:00.031

That's not a lot of time wasted but it does affect compile times a
little bit. I wonder if DMD could be improved a bit in this regard.

Re: Keeping imports clean

[Guillaume Chatelet]

Thanks for the quick answer. Indeed it's by far less relevant 
than for C++ but a build tool still needs to figure out the 
dependencies. I know D is very fast to compile but you still want 
to keep compilation at a minimum. Wouldn't it matter for a very 
big project ?

Re: Keeping imports clean

[James Miller]

On 2 April 2012 10:12, Guillaume Chatelet  wrote:
> In C++ it clearly matters to have very clean dependencies to keep
> compilation time as low as possible ( Google even built a tool to check
> unused #include - http://code.google.com/p/include-what-you-use ).
>
> So I was telling to myself it would be great to have the D compiler report
> about unused import because it might already have all the necessary
> information. But maybe such a tool already exists ? Or maybe this is simply
> irrelevant ?

D doesn't have includes, importing a module that you don't use doesn't
matter because D only needs the imports to find function declarations.
This is clear in the import syntax:

import std.random : uniform //import only uniform from the std.random module

so it is a symbolic import, not a textual import. Also note that while
D has .di ("D Interface") files, they are not required, and often
people don't even bother with them, merely distributing the source.

So in short, it isn't relevant at all, since there is no preprocessor
to f**k things up.

--
James Miller

Re: Keeping imports clean

[q66]

On Sunday, 1 April 2012 at 22:13:00 UTC, Guillaume Chatelet wrote:
In C++ it clearly matters to have very clean dependencies to 
keep compilation time as low as possible ( Google even built a 
tool to check unused #include - 
http://code.google.com/p/include-what-you-use ).


So I was telling to myself it would be great to have the D 
compiler report about unused import because it might already 
have all the necessary information. But maybe such a tool 
already exists ? Or maybe this is simply irrelevant ?


in c++ it's text expansion, D imports are symbolic; it's not by 
far as relevant