synchronized keyword

[Walter Bright]

Robert Libby wrote:
> I'm relatively new to D, but I’d just like to say kudos to Mr. Bright for
> creating such a wonderful language!
> 
> I just ran across an interesting issue.  I may have missed something somewhere,
> but, I had a function inside of a class declared:
> 
> public class Logger {
> ..
> public synchronized void log(char s[]) {
> printf("The log entry is %.*s\n", s);
> }
> ..
> }
> 
> I was under the impression that this would safely lock a mutex so that it would
> be thread safe (as it would in Java).  However, I found instances where the
> output of two threads were happening at the same time, producing garbled output.
> 
> I changed the code to:
> public void log(char s[]) {
> synchronized {
> printf("The log entry is %.*s\n", s);
> }
> }
> 
> Which seemed to work as expected.

synchronized as a statement with no object in () means it syncs on a 
global mutex.

> So my question is, what does putting synchronized in the declaration do,

It synchronizes on the instance of Logger. You can see it in the 
generated code (try running obj2asm on it).

> and why
> doesn't it give a warning or error if it is not supposed to be there?

It not working on your code suggests that two different instances of 
Logger were calling log?