[fpc-pascal] Generic type conflicts

Jonas Maebe jonas at freepascal.org
Fri Nov 8 17:04:24 CET 2019

On 08/11/2019 17:02, Ben Grasset via fpc-pascal wrote:
> The original C++ version used "constexpr" template parameters to
> determine at compile time whether or not the user-provided comparison
> function was one for which it should use the "branchless" version of its
> code for item partitioning or not, and based on that passed the boolean
> "true" or "false" result as another constant template parameter.
> The end result of course being that the compiled code is always tuned
> precisely to the given comparison function, without any kind of runtime
> selection based on non-constant boolean function parameters (which is
> what I've currently had to write the "branchless" choice as, defaulting
> to "true" unless the user specifies otherwise.)
> With Ryan's patch, I'll at least be able to write that choice as a
> constant parameter instead, although I'm unaware of any way to replicate
> actually having the compiler *make* the choice.

You can't. It's the main difference between C++ templates, which is a
Turing-complete programming language, and generics, which is simply a
parametrising mechanic.


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