5 ms·

This is similar to the C preprocessor trick STRINGIZE: #define STRINGIZE_DETAIL(x) #x #define STRINGIZE(x) STRINGIZE_DETAIL(x)

gpderetta 8y ago
It probably uses stringification under the hood, but then relies on constexpr to "canonicalize" the name (removing everything before the dot, template parameters etc).
- Someone 8y ago
  From cursory reading, it seems it doesn’t, at all. It uses compiler-specific predefined values __PRETTY_FUNCTION__ (gcc, clang) or __FUNCSIG__ (MS Visual C++), and doesn’t work on other compilers. It also has to do work to extract the function name from the char arrays/C strings that those macros expand to. Reading answers to https://stackoverflow.com/questions/4384765/whats-the-difference-between-pretty-function-function-func/26907887 https://stackoverflow.com/questions/4384765/whats-the-differ..., it seems it would have been easier to use the __FUNCTION__ in gcc, but I’m not familiar with that (or the other predefined values) at all, so who knows?
  - anon4242 8y ago
    Actually, __FUNCTION__ won't work as it only expands to the name of the function, not any templates or arguments. It's actually a pretty clever way to automagically deduce not only names of variables but also of enums :). Too bad it's most likely not maintainable in the long run as compilers probably change what their __PRETTY_FUNCTION__ (or equivalent) macros expand to in new versions.
    - neargye 8y ago
      I usually check the newest versions of compilers, and if the behavior changes, then I update the code
  - asveikau 8y ago
    Last I knew __FUNCTION__ in GCC doesn't even do name de-mangling. You'd get the raw C symbol name with no C++ types.
    - neargye 8y ago
      https://stackoverflow.com/a/31163837/9514814 https://stackoverflow.com/a/31163837/9514814
      - asveikau 8y ago
        Gcc 7. I could be wrong but I seem to recall a long time ago, when I was learning this stuff in the 90s, __FUNCTION__ wouldn't even demangle.
        neargye 8y ago
        yeap, I use __PRETTY_FUNCTION__.
- neargye 8y ago
  You are absolutely right :)
asveikau 8y ago
That was what I was thinking, then I saw that this will stringify enum values, eg. nameof(c) returns "RED", which the preprocessor #x will not do.
- CalChris 8y ago
  I only use STRINGIZE for error messages. I learned about it from reading the source for assert macros.
- neargye 8y ago
  To be sure: nameof(c) returns "c" (nameof return name of variable) nameof_enum(c) returns "RED" (nameof_enum return enum name of enum variable)

gpderetta 8y ago

It probably uses stringification under the hood, but then relies on constexpr to "canonicalize" the name (removing everything before the dot, template parameters etc).

Someone 8y ago
From cursory reading, it seems it doesn’t, at all. It uses compiler-specific predefined values __PRETTY_FUNCTION__ (gcc, clang) or __FUNCSIG__ (MS Visual C++), and doesn’t work on other compilers. It also has to do work to extract the function name from the char arrays/C strings that those macros expand to. Reading answers to https://stackoverflow.com/questions/4384765/whats-the-difference-between-pretty-function-function-func/26907887 https://stackoverflow.com/questions/4384765/whats-the-differ..., it seems it would have been easier to use the __FUNCTION__ in gcc, but I’m not familiar with that (or the other predefined values) at all, so who knows?
- anon4242 8y ago
  Actually, __FUNCTION__ won't work as it only expands to the name of the function, not any templates or arguments. It's actually a pretty clever way to automagically deduce not only names of variables but also of enums :). Too bad it's most likely not maintainable in the long run as compilers probably change what their __PRETTY_FUNCTION__ (or equivalent) macros expand to in new versions.
  - neargye 8y ago
    I usually check the newest versions of compilers, and if the behavior changes, then I update the code
- asveikau 8y ago
  Last I knew __FUNCTION__ in GCC doesn't even do name de-mangling. You'd get the raw C symbol name with no C++ types.
  - neargye 8y ago
    https://stackoverflow.com/a/31163837/9514814 https://stackoverflow.com/a/31163837/9514814
    - asveikau 8y ago
      Gcc 7. I could be wrong but I seem to recall a long time ago, when I was learning this stuff in the 90s, __FUNCTION__ wouldn't even demangle.
      - neargye 8y ago
        yeap, I use __PRETTY_FUNCTION__.
neargye 8y ago
You are absolutely right :)

asveikau 8y ago

That was what I was thinking, then I saw that this will stringify enum values, eg. nameof(c) returns "RED", which the preprocessor #x will not do.

CalChris 8y ago
I only use STRINGIZE for error messages. I learned about it from reading the source for assert macros.
neargye 8y ago
To be sure: nameof(c) returns "c" (nameof return name of variable) nameof_enum(c) returns "RED" (nameof_enum return enum name of enum variable)