Voting: std.logger

[Marco Leise via Digitalmars-d]

Am Sun, 31 Aug 2014 01:09:32 +0000
schrieb "Ola Fosheim Grøstad"
<ola.fosheim.grostad+dlang at gmail.com>:

> I've got some questions:
> 
> How does logging interact with pure? You need to be able to log 
> in pure functions.

How do you come to that conclusion? Purity is a synonym for
_not_ having side effects. That said - as usual - "debug"
statements allow you to punch a hole into purity.

> […]
> 
> Is logf() needed? Can't you somehow detect that the string is an 
> immutable string literal with string formatting characters?

1) The first argument does not need to be a literal.
2) Checking the first argument for formatting chars slows the
   system down.
3) If you want to log a regular string, e.g. an incoming HTTP
   request or something that contains formatting symbols, log()
   would throw an exception about a missing second argument.
   This in turn could become a DOS vulnerability.

Other than that, you could create an additional log function
that only accepts compile-time known formatting strings as a CT
argument and verifies the runtime argument types at the same
time.

-- 
Marco