Programming languages

Table of Contents

• Programming languages
  • Subsets of C++ used in code_saturne
  • Subsets of C++ not (or rarely) used in code_saturne.

Programming languages

The code_saturne tool is written mostly in C++, but was only recently converted from C, so most programming constructs encountered in the code will be Very similar to C rather than "modern" C++.

Subsets of C++ used in code_saturne

• Functions with the same name but different arguments. This "syntaxic sugar" can allow handling variants of a function without requiring long and excessively verbose names.
• Templated functions. Using templated types allows a single function for various data types, which allows for better code factoring.
• Lambda functions. Lambda functions are an essential part of the cs_dispatch mechanism used to handle local parallel constructs, and enabling generation of CPU and GPU execution from the same source code.

Subsets of C++ not (or rarely) used in code_saturne.

• Class methods. Since most of code_saturne was only recently converted to C++, although many structures use an object-oriented approach, they are still only defined as C structures and do not (yet) use a C++ method syntax.
  • For example, given a cs_field_t structure *f, we can call a = cs_field_get_key_double(f, k), but not a = f->get_key_double(k).
  • For the same reason, constructors and destructors are explicit.
• Inheritance. For the same reasons, code_saturne does do not currently use class inheritance. Class inheritance may be used in the future, though caution must be used with virtual methods, to avoid performance issues (i.e. these must be used only for high-level contructs and operations).
• Exceptions. Actually, a few try/catch exceptions handling examples may be found in the SYCL portions of the code, but exceptions must be avoided in performance-ciritical portions of the code (and were not available in C).