Quite sure a simple basic problem...

[docandrew via Digitalmars-d-learn]

On Thursday, 2 June 2016 at 00:37:58 UTC, WhatMeWorry wrote:
> I've got a fairly complex D project (25+ modules) that has 
> grown haphazardly over time. So it is not well designed. But I 
> want to get the thing fully ported before refining the code. 
> (that's called refactoring, I believe?)
>
> Anyway, there is a new module called audio.d which which has 
> all the sound functionality.
>
> And in the (main.d) module is a code snippet like so
>
> void main(string[] argv)
> {
>     // . . .
>     auto blop = new AlurePlaySound("../bleep.wav");
>     blop.play();
>     // . . .
> }
>
> So all is well and good except I need to place the sound in 
> another module (game.d) where
> collisions are detected.
>
> I tried:
>
> module game;
> import main;   // is this as ugly as I think it is?
>
> if (collision[0])  // If collision make sound
>     blop.play();
>
>
> but this returns:  game.d(501): Error: undefined identifier 
> 'blop'
>
>
> So can someone tell me what various solutions to this problem 
> or type of problems?  I presume there are quick and dirty 
> solutions (like here) and more elegant solutions?
>
> Would this type of problem fall under the domain of "scope".  
> Like in global scope. But I don't think D has such a concept.
>
> Thanks.

Since blop is being declared inside your main() function, it 
isn't visible to other modules or functions. You're right that 
the issue is a problem of "scope".

Importing your main module will work, but you must declare your 
as a global variable outside the main() function.

i.e.

----------------------

module main;

AlurePlaySound blop;

void main()
{
    //etc...

    blop = new AlurePlaySound("../beep.wav");

    //etc...
}

----------------------

module game;

import main;

void collision()
{
     blop.play(); //or whatever
}

If your game loop is running in a separate thread, then I think 
you'll want to use:

__gshared AlurePlaySound blop;

for the declaration, since variables are thread-local by default.

Using global variables is generally frowned upon for production 
code because you can never be sure which functions are modifying 
it. But for a quick hack, it works! A better option might be to 
make a third module with a class containing all your audio 
objects, initialize it in main(), and then pass it to your main 
game loop.

-Jon