Hello everyone!

I try to compile this recipe with dmd (2.089.0), ldc2 (1.18.0):
https://wiki.dlang.org/Using_string_mixins_for_logging
but get the same error:

mixin_log.d(64): Error: basic type expected, not __FUNCTION__
mixin_log.d(64): Error: declaration expected, not __FUNCTION__

in that part of code:

mixin template set_func_name(string fn)
{
    enum __FUNCTION__ = fn;
}

There is no doubt that this recipe once worked. How to fix it now?

On Wednesday, 15 July 2020 at 07:07:55 UTC, Vitalii wrote:
> Hello everyone!
>
> I try to compile this recipe with dmd (2.089.0), ldc2 (1.18.0):
> https://wiki.dlang.org/Using_string_mixins_for_logging
> but get the same error:
>
> mixin_log.d(64): Error: basic type expected, not __FUNCTION__
> mixin_log.d(64): Error: declaration expected, not __FUNCTION__
>
> in that part of code:
>
> mixin template set_func_name(string fn)
> {
>     enum __FUNCTION__ = fn;
> }
>
> There is no doubt that this recipe once worked. How to fix it now?

that wiki entry is from 2012. __FUNCTION__, __PRETTY_FUNCTION__ and __MODULE__ were introduced in 2013, making that old __FUNCTION__ definition code obsolete.

In fact all of the code on that page can now be more easily written as:


enum LogLevel { INFO, WARN, ERROR }

template log(LogLevel level)
{
    void log(Args...)(Args args, string fn = __FUNCTION__, string file = __FILE__, size_t line = __LINE__)
    {
        writeln(Clock.currTime(), " [", level, "] ", file, '(', line, "): ", fn, ": ", args);
    }
}

alias info = log!(LogLevel.INFO);
alias warn = log!(LogLevel.WARN);
alias error = log!(LogLevel.ERROR);


no longer requiring any mixins or boilerplate code in your calling functions.

---

void main(string[] args)
{
    info("hello", "world");
    warn("i am ", "number ", 1);
    error(true);
    log!(LogLevel.INFO)("manual call");
}

>>>

2020-Jul-15 08:12:00.5900346 [INFO] onlineapp.d(21): onlineapp.main: helloworld
2020-Jul-15 08:12:00.5901559 [WARN] onlineapp.d(22): onlineapp.main: i am number 1
2020-Jul-15 08:12:00.5901745 [ERROR] onlineapp.d(23): onlineapp.main: true

---

This uses default values after variadic parameters which is allowed since 2.079.0 and also uses a nested template to allow for the aliases with default LogLevel.

Many thanks!

On Wednesday, 15 July 2020 at 07:36:49 UTC, Vitalii wrote:
> Many thanks!

I have now deprecated the old wiki page and linked to a new one with more examples: https://wiki.dlang.org/Logging_mechanisms