Embedded C++ : to use STL or not?

Question

I have always been an embedded software engineer, but usually at Layer 3 or 2 of the OSI stack. I am not really a hardware guy. I have generally always done telecoms product

Answer 1

The biggest problem with STL in embedded systems is the memory allocation issue (which, as you said, causes a lot of problems).

I'd seriously research creating your own memory management, built by overriding the new/delete operators. I'm pretty sure that with a bit of time, it can be done, and it's almost certainly worth it.

As for the exceptions issue, I wouldn't go there. Exceptions are a serious slowdown of your code, because they cause every single block ({ }) to have code before and after, allowing the catching of the exception and the destruction of any objects contained within. I don't have hard data on this on hand, but every time I've seen this issue come up, I've seen overwhelming evidence of a massive slowdown caused by using exceptions.

Edit:
Since a lot of people wrote comments stating that exception handling is not slower, I thought I'd add this little note (thanks for the people who wrote this in comments, I thought it'd be good to add it here).

The reason exception handling slows down your code is because the compiler must make sure that every block ({}), from the place an exception is thrown to the place it is dealt with, must deallocate any objects within it. This is code that is added to every block, regardless of whether anyone ever throws an exception or not (since the compiler can't tell at compile time whether this block will be part of an exception "chain").

Of course, this might be an old way of doing things that has gotten much faster in newer compilers (I'm not exactly up-to-date on C++ compiler optimizations). The best way to know is just to run some sample code, with exceptions turned on and off (and which includes a few nested functions), and time the difference.