> On (15 May 97) Louis Rizzuto wrote to Carey Bloodworth...
 > LR> Is it plausible to write such RT apps in C++ - and still meet real
 > LR> time criteria?  I am not sure.  Perhaps some else here can comment 
 > LR> on this.
 > Yes.  There's not a lot of difference between doing RT
 > programming in
 > C and in C++.  In both cases, there are some obvious
 > restrictions such
 > as on using dynamic memory allocation unless your library has
 > an
 > allocator with know worst-case speed.
 > One thing that does change is that typical C++ programs _do_
 > tend to use
 > dynamic allocation more than their C counterparts, at least
 > in my
 > experience.  Likewise, it's not necessarily as easy to "see"
 > which
 > things are likely to consume time by examining source code. 
 > For
 > instance in C an assignment statement:
 >     a = b;
 > is always going to be relatively simple and straightforward. 
 > About the
 > only time it's going to consume significant time is if `a'
 > and `b' are
 > struct's of relatively large size.
 > However, in C++, that same assignment statement might
 > disguise an
 > arbitrary amount of complex code, and may well involve a
 > number of
 > function calls.
 > However, in both cases things come out more or less the same
 > in any
 > case: you've got to find your absolute worst-case path
 > through the code
 > and you've got to verify that it's within requirements.
 
Thanks for replying Jerry.  In Real Time apps, both memory and execution time 
are often critical.  I agree that typically C++ pgms use dynamic allocation 
of memory but I wonder if this is adviseable in a C++ RT app due to typical 
RT memory constraints.  
C++ complex generated code may add to the problem of controlling both
memory and execution times.  C++ is primarily a language noted for 
reuseability of code; but are RT apps so similar that they would benefit from 
such reuseabilty?  If the guess that C++ can be used in a RT envirnment 
proves to be a fiasco backing off and back to 'C' and ass'y may cancel out 
any perceived labor benefits from using C++.
What do you think, Jerry?
For that matter why not use Java since it claims portabilty and is coming on 
strong as the future development environment?
 
Regards, -= Lou =-
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