Re: singleton template

From:
"mlimber" <mlimber@gmail.com>
Newsgroups:
comp.lang.c++
Date:
3 Jul 2006 08:08:11 -0700
Message-ID:
<1151939291.742574.32920@j8g2000cwa.googlegroups.com>
Tilman Kuepper wrote:

Hi Nick,

there are indications that the constructor is getting called more
than once in some circumstances (tracing in one of the
instantiations of the template).

Are there potential problems with the use of static data?


I had exactly this problem when using Visual C++ 6.0. But only
in Release mode, not in Debug mode. Perhaps a problem with
the optimizer...?!


Possible but it seems more likely that this is symptomatic of other
latent problems. See "Surviving the Release Version" by Joseph M.
Newcomer:

http://www.flounder.com/debug_release.htm

Particularly, this section:

http://www.flounder.com/debug_release.htm#Compiler%20Bugs%20(again)

The solution was to move the implementation of the instance()
method from the .h to the .cpp file.


That's generally a bad idea. Absent the export keyword, for
maintainability the function should be in the header. Duplicating it by
hand in every file that needs it is a maintenance nightmare. (I should
note that one of my compilers complained if I defined the Instance()
function given elsewhere in this thread inline in the class definition,
but moving it outside the class definition but still in the header file
quelled the complaint but kept maintenance the same.)

Cheers! --M

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