代码之家 › 专栏 › 技术社区 › Duck Dodgers

如何在C++中“退出当前函数,如果当前语句出现错误”

runtime-error macros logging c c++

Duck Dodgers · 技术社区 · 6 年前

我从一个例子开始阐述我的问题。最后以问题的确切陈述结束。

在C语言中,我们可以编写这样的宏,

#define NO_ERROR 0
#define RETURN_IF_ERROR(function)                                       \
{                                                                       \
  RetCode = function;                                                   \
  if (RetCode != NO_ERROR)                                              \
  {                                                                     \
      LOG(ERROR,"[%d] line [%d] [%s]", RetCode, __LINE__, __FILE__ ) ); \
      return RetCode;                                                   \
  }                                                                     \
  else {                                                                \
      LOG(VERBOSE,"[%d] line [%d] [%s]", RetCode, __LINE__, __FILE__ ) );\
  }                                                                     \
}

现在这个宏可以用在这样的函数中,

int ConstructAxes() {
    RETURN_IF_ERROR(GetAxis("alpha"));
    RETURN_IF_ERROR(GetAxis("beta"));
    RETURN_IF_ERROR(GetAxis("gamma"));
    RETURN_IF_ERROR(GetAxis("delta"));
    .
    .
    .
}

因此,我们立即退出当前函数(如constructaxs),并返回一个错误代码,如果在中调用的函数之一返回错误代码。如果没有这个宏,对于这4个语句中的每一个,我都必须编写一个if…else块。最后,我将使用4行代码来显示实际的功能或任务,然后再使用16行错误检查(和/或可选的日志记录)。(我见过700多行的函数,只有20到30行的函数和600多行的if…else错误检查和日志记录。不太容易遵循主逻辑。)

(另外,在有人指出之前,我不能使用例外。这是一个遗留项目,不使用异常,也不希望使用异常,我也不是编写异常安全代码的专家。同样,在任何人指出之前,返回的错误代码在更高的层次上被重新解释为一些有意义的文本。在哪里以及如何与手头的这个问题无关。)

问题是,宏可能有问题,我更喜欢函数。那么,在C++中,有没有使用宏的一些简洁而优雅的方法呢?我觉得这是不可能的。

5 回复 | 直到 6 年前

Jarod42 6 年前

int RunFunctions(int line, // __LINE__
                 const char* file, // __FILE__
                 std::initializer_list<std::function<int()>> functions)
{
    int counter = 0;
    for (auto f : functions) {
        auto RetCode = f();

        if (RetCode != NO_ERROR) {
            LOG(ERROR,"[%d] line [%d] [%s] [%d]", RetCode, line, file, counter ));
            return RetCode;
        } else {
            LOG(VERBOSE,"[%d] line [%d] [%s] [%d]", RetCode, line, file, counter ) );
        }
        ++counter;
    }
    return NO_ERROR;
}

int ConstructAxes() {
    return RunFunctions(__LINE__, __FILE__, {
        []() { return GetAxis("alpha"); },
        []() { return GetAxis("beta"); },
        []() { return GetAxis("gamma"); },
        []() { return GetAxis("delta"); }
    });
}

std::source_location __LINE__ __FILE__

std::function

Serge Ballesta 6 年前

  int test_and_log(int RetCode) {
    if (RetCode != NO_ERROR)
      {
          LOG(ERROR,"[%d] line [%d] [%s]", RetCode, __LINE__, __FILE__ ) );
      }
      else {
          LOG(VERBOSE,"[%d] line [%d] [%s]", RetCode, __LINE__, __FILE__ ) );
      }
    return RetCode;
  }

#define RETURN_IF_ERROR(x) { int cr; if ((cr = test_and_log(x)) != NO_ERROR) return cr; }

int ConstructAxes() {
    RETURN_IF_ERROR(GetAxis("beta"));
    RETURN_IF_ERROR(GetAxis("gamma"));
    RETURN_IF_ERROR(GetAxis("delta"));
    .
    .
    .
    return 0;                            // ensure a return value if every line passes
}

  void test_and_log(int RetCode) {
    if (RetCode != NO_ERROR)
      {
          LOG(ERROR,"[%d] line [%d] [%s]", RetCode, __LINE__, __FILE__ ) );
          throw RetCode;
      }
      else {
          LOG(VERBOSE,"[%d] line [%d] [%s]", RetCode, __LINE__, __FILE__ ) );
      }
  }

int ConstructAxes() {
  try {
    test_and_log(GetAxis("beta"));
    test_and_log(GetAxis("gamma"));
    test_and_log(GetAxis("delta"));
    .
    .
    .
  }
  catch (int RetCode) {
    return RetCode;
  }
  return 0;                            // ensure a return value if every line passes
}

std::exception

test_and_log inline

Sander De Dycker 6 年前

int ConstructAxes() {
    int retCode = NO_ERROR;

    auto fail_if_error = [&retCode](int result) -> bool {
        retCode = result;
        if (retCode != NO_ERROR) {
            LOG(ERROR, "[%d] line [%d] [%s]", retCode, __LINE__, __FILE__);
            return false;
        }
        LOG(VERBOSE, "[%d] line [%d] [%s]", retCode, __LINE__, __FILE__);
        return true;
    };

    fail_if_error(GetAxis("alpha"))
      && fail_if_error(GetAxis("beta"))
      && fail_if_error(GetAxis("gamma"))
      && fail_if_error(GetAxis("delta"));

    return retCode;
}

mnistic 6 年前

#define RETURN_IF_ERROR(function)                                       \
{                                                                       \
  RetCode = function;                                                   \
  if (RetCode != NO_ERROR)                                              \
  {                                                                     \
      goto return_with_error;                                                   \
  }                                                                     \
  else {                                                                \
      LOG(VERBOSE,"[%d] line [%d] [%s]", RetCode, __LINE__, __FILE__ ) );\
  }                                                                     \
}

int ConstructAxes() {
    int RetCode;
    RETURN_IF_ERROR(GetAxis("alpha"));
    RETURN_IF_ERROR(GetAxis("beta"));
    RETURN_IF_ERROR(GetAxis("gamma"));
    RETURN_IF_ERROR(GetAxis("delta"));
    .
    .
    .
    return RetCode;
return_with_error:
    cleanup();
    LOG(ERROR,"[%d] line [%d] [%s]", RetCode, __LINE__, __FILE__ ) );
    return RetCode;
}

in C is fine

alk 6 年前

do {... break on error ...} while(0)

break

#define NO_ERROR (0)

// log level IDs
#define LL_ERROR (0)
// more log levels here
#define LL_VERBOSE (10)
// more log levels here
#define LL_DEBUG (13)
// more log levels here
#define LL_MAXIMUM (16)

// log level long names
static const char * log_level_names[LL_MAXIMUM] = {
  "error",
  // more here
  "verbose"
  // more here
  "debug"
  // more here
}

int loglevel = LL_ERROR; // default logging-level to error; to be set to any LL_xxxx

// return date-time-stamp string (can be any, and most likely should be ;-)
#define DATETIMESTAMP_STR asctime(localtime(time(NULL)))

// Generic logging
#define LOG(ll, fmt, rc, ...) \
  while (ll <= loglevel) { \
    fprintf(stderr, "%s [%s]: " fmt, DATETIMESTAMP_STR, log_level_name[loglevel], __VA_ARGS__); \
    break; \
  };

// Specific logging
#define LOG_ERROR_OR_VERBOSE(rc, line, fname) \
  do { \
    LOG(NO_ERROR != (rc) ?LL_ERROR :LL_VERBOSE, "[%d] line [%d] [%s]", rc, line, fname); \
  while (0)


int foo(void)
{
  int result = NO_ERROR;

  LOG(LL_DEBUG, "entering '%s'", __func__);

  do {
    result = bar1(...);
    LOG_ERROR_OR_VERBOSE(result, __LINE__, __FILE__);
    if (NO_ERROR <> result) 
      { break; }

    result = bar2(...);
    LOG_ERROR_OR_VERBOSE(result, __LINE__, __FILE__);
    if (NO_ERROR <> result) 
      { break; }

    ...
  } while (0);

  LOG(LL_DEBUG, "leaving '%s' (rc = %d)", __func__, result);

  return result;
}

if (NO_ERROR <> result) 
  { break; }

if (NO_ERROR <> result) { break; }

result = bar1(...);
LOG_ERROR_OR_VERBOSE(result, __LINE__, __FILE__);

LOG_ERROR_OR_VERBOSE(result = bar1(...), __LINE__, __FILE__);