Re: Concatenation and Characters

[Mark Biggar <mark.a.biggar@attbi.com>]

Programmer Dude wrote:
> Mark Biggar wrote:
> 
> 
>>Becasue evaluating an uninitialized variable is only a bounded error,
>>which is handled at run-time.
> 
> 
> I'm new to, and just beginning to explore, Ada.  It surprised me that
> Ada allows evalutation of an uninitialized variable without saying
> *something* about it during compile.
> 
> Surely I'm missing something?

It should be obvious that the general problem of detecting all
accesses to uninitialized variables is equivalent to the halting
problem.  So it is impossible for a compiler to do a perfect job, thus
some form of run-time detection or action is necessary anyway.  So the
LRM can't require compile time detection, so it makes it optional.  The
LRM does allow compilers to warn you when you write code that will
always raise an expection and as raising Program_Error is one of the
allowed run-time responses to accessing an uninitialized variable the
LRM does allows for optional warnings for this case.  If your complier
doesn't issue such warnings, it's only a "quality of implementation"
issue not a compiler bug.

-- 
Mark Biggar
mark.a.biggar@attbi.com