change mixins

[sybrandy]

On 02/15/2010 05:37 PM, Pelle Månsson wrote:
> On 02/15/2010 10:53 PM, sybrandy wrote:
>> In short: I'm using mixins so that the person who's using the library
>> doesn't have to put in version(DoLogging)... all over the place. By
>> containing it in one location, I was trying to keep the code using the
>> library cleaner.
> void trace(string s) {
> version (NoTrace) {
> //do nothing
> } else {
> //do tracing
> }
> }
>
> trace("Stuff");
>
> will this not work?

It will work, however I was going for "if you're not logging, why have 
the logging code in there?"  Like I said, I was going for performance 
and with mixins I could ensure there was no runtime overhead with 
instantiating the class, setting up the logger, etc. when the user 
turned logging off.

In this version:


template Trace(string msg)
{
     version (NoLogging)
     {
     }
     else
     {
         // Write to the log file...
     }
}

If NoLogging is turned on, then no code to perform the logging is even 
added to the file.  It seemed to me that this was favorable to having a 
bunch of empty functions laying around.  Now, if DMD was smart enough to 
eliminate empty functions, that would be great and I wouldn't have to do 
this.

Regardless, I'm still all for moving the "mixin" keyword to the mixin 
declaration vs. where it's instantiated.