On Wednesday, 22 February 2017 at 22:37:25 UTC, Profile Anaysis
wrote:
On Wednesday, 22 February 2017 at 21:27:47 UTC, WhatMeWorry
wrote:
I'm doing conditional compilation using static ifs like so:
enum bool audio = true;
// if audio flag is present and set to true, add to code build
static if ( (__traits(compiles, audio)) && audio)
playSound(soundSys, BLEEP );
This works, but I thought there might be a simpler way. For
instance,
after perusing std.traits, I thought I would find something
like
isPresent(audio) or isSymbol(audio) templates.
Or am I being obtuse here?
Thanks.
You do realize that audio is a compile time constant? This
means that in the binary, everything that depends on it is
evaluated(as it can be, since it is known). This means that
whatever app you are using will not be able to be able to
"adapt" to the system changes. In this case, if the system has
audio there is no way for the binary to use it because you
compiled it out(if audio = false).
In such a case you do not want to use a static or compile time
variable unless you plan on creating multiple binaries.
If your example above was just for demo then yes, you can do
that but compiles is not what you want. Compiles only checks if
the statement that follows is compilable as valid D code and it
doesn't have anything to do with the value of the variables.
Definitely overthought this one big time. But there is so much
meta goodness in std.traits that I felt compelled to use
"compiles" :)
There are a few options:
1. static if(audio)
2. version(audio)
3. if (audio)
It looks like you are trying to create the version(audio)
semantic(if exists then use, else don't).
Ultimately, though, if you are trying to make a binary that can
either use audio or not depending on where it is ran, you'll
have to stick to using actual run time variables and probably
be a bit more organized about it.
option 1 is the one I was shooting for. does the static if
(audio) just check for the existence of audio, or does it also
check to see if audio is true as well?
I've got a game tutorial with 15 sequential projects. Each
project introduces a new concept by building on the previous
project code. But I soon had so much
code duplication that I decided to use common modules/functions.
The specific code could be injected via flags in the apps.d
Hence my original question.
