[cmake-developers] $LIST_LENGTH{} syntax

[Torsten at Robitzki.de]

> Am 22.01.2019 um 17:03 schrieb Brad King <brad.king at kitware.com>:
> 
> Yes, something more extensible would be fine.  We need to be careful
> not to slow down the variable reference syntax parser though.

Currently, the Code that evaluates the ${}-Syntax only evaluates the key, if the key is not an empty string:

const char* cmCommandArgumentParserHelper::ExpandSpecialVariable(
  const char* key, const char* var)
{
  if (!key) {
    return this->ExpandVariable(var);
  }
  if (!var) {
    return "";
  }
  if (strcmp(key, "ENV") == 0) {
    std::string str;
    if (cmSystemTools::GetEnv(var, str)) {
      if (this->EscapeQuotes) {
        return this->AddString(cmSystemTools::EscapeQuotes(str));
      }
      return this->AddString(str);
    }
    return "";
  }
  if (strcmp(key, „CACHE") == 0) {

…

so, there seems to be no risk to slow down the ExpandVariable()-Path (but of cause, I would measure the difference).

kind regards,

Torsten
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