scope(exit) considered FREAKING AWESOME

Sun Nov 8 13:15:14 PST 2009

Justin Johansson wrote:
> downs Wrote:
> 
>> auto var = hairilyAllocatedObject();
>> scope(exit) cleanupObject(var);
>>
>> sock.send("<html><head></head><body>");
>> scope(exit) sock.send("</body></html>");
>>
>> logln("Digraph D {");
>> scope(exit) logln("}");
>>
>> SDL_LockSurface(display.surface);
>> scope(exit) SDL_UnlockSurface(display.surface);
>>
>> auto dg = { performComplexExitCleanupDuty; };
>> scope(exit) dg();
>> ....
>> dg = dg /apply/ (proc dg) { moreCleanup; dg(); };
>> ....
>> /* Half a dozen different ways of leaving the function go here */
>>
>> auto backup = var; var = newValue;
>> scope(exit) var = backup;
> 
> Yes fine.  You demonstrate the cool use of scope(exit) but
> this is a bit like kidding yourself and conscientiously
> thinking you didn't *actually* tell a lie because you just
> withheld information.
> 
> Conspicuous, by the absence of, in your examples is any
> use of scope(exit) inside curly-brace scope statements
> embedded *inside* a function.
> 
> Your examples look fine if one assumes scope(exit) as
> relating to function scope.
> 

I assume scope(exit) is relating to whatever scope I'm currently in. I'm not sure how my examples oppose that.

When I do scope(exit) in a while loop, I expect it to be run at the end of the loop, not at the end of the function.

Don't blame the language for your misunderstanding of it.