[cmake-developers] Questions about coding conventions

[Ben Boeckel]

On Mon, Jun 13, 2016 at 00:03:29 +0200, Daniel Pfeifer wrote:
> Can you show an example? To be clear: We are looking for a function,
> that has a code path for `str == NULL` and a *different* codepath for
> `str[0] = '\0'`.

As input to functions? Usually NULL means "unset". See properties,
variable values, etc. As an output, any place which doesn't care should
already be using GetSafeDefinition().

As a concrete example, `set(CACHE)` cares about NULL versus *s == NULL:

    const char* existingValue = state->GetCacheEntryValue(variable);
    if (existingValue &&
        (state->GetCacheEntryType(variable) != cmState::UNINITIALIZED)) {
      // if the set is trying to CACHE the value but the value
      // is already in the cache and the type is not internal
      // then leave now without setting any definitions in the cache
      // or the makefile
      if (cache && type != cmState::INTERNAL && !force) {
        return true;
      }
    }

    // if it is meant to be in the cache then define it in the cache
    if (cache) {
      this->Makefile->AddCacheDefinition(variable, value.c_str(), docstring,
                                         type, force);
    } else {
      // add the definition
      this->Makefile->AddDefinition(variable, value.c_str());
    }

--Ben