A simple little design-by-contract library to test out more advanced c++20 features. Looks like clang doesn't do std::source_location right. See https://github.com/llvm/llvm-project/issues/56379

PPP3/dbc.h

@@ -0,0 +1,59 @@
+#include <string>
+#include <source_location>
+#include <fmt/core.h>
+
+using namespace std;
+
+namespace dbc {
+  class Error {
+    public:
+      const string message;
+      Error(string m) : message{m} {}
+      Error(const char *m) : message{m} {}
+  };
+
+  class CheckError : public Error {};
+
+  class SentinelError : public Error {};
+  class PreCondError : public Error {};
+  class PostCondError : public Error {};
+
+  void log(const string &message, std::source_location loc = std::source_location::current()) {
+    fmt::print("[{}:{}:{}] {}\n", loc.file_name(), loc.function_name(), loc.line(), message);
+  }
+
+  void sentinel(const string &message, std::source_location loc = std::source_location::current()) {
+    string err = fmt::format("[SENTINEL! {}:{}:{}:{}] {}\n",
+          loc.file_name(), loc.function_name(),
+          loc.line(), loc.column(), message);
+    throw SentinelError{err};
+  }
+
+  void pre(const string &message, std::function<bool()> tester, std::source_location loc = std::source_location::current()) {
+    if(!tester()) {
+      string err = fmt::format("[PRE! {}:{}:{}:{}] {}\n",
+          loc.file_name(), loc.function_name(),
+          loc.line(), loc.column(), message);
+      throw PreCondError{err};
+    }
+  }
+
+  void post(const string &message, std::function<bool()> tester, std::source_location loc = std::source_location::current()) {
+    if(!tester()) {
+      string err = fmt::format("[POST! {}:{}:{}:{}] {}\n",
+          loc.file_name(), loc.function_name(),
+          loc.line(), loc.column(), message);
+      throw PostCondError{err};
+    }
+  }
+
+  void check(bool test, const string &message, std::source_location loc = std::source_location::current()) {
+
+    if(!test) {
+      string err = fmt::format("[CHECK! {}:{}:{}:{}] {}\n",
+          loc.file_name(), loc.function_name(),
+          loc.line(), loc.column(), message);
+      throw CheckError{err};
+    }
+  }
+}

PPP3/goc.cpp

@@ -5,12 +5,14 @@
 #include <string>
 #include <iterator>
 #include <ctime>
+#include "dbc.h"
 
 using namespace std;
 using namespace fmt;
 
 int main()
 {
+  try {
     regex err_re("(.*?):([0-9]+):([0-9]+):\\s*(.*?):\\s*(.*)");
     string line;
     smatch err;
@@ -19,6 +21,10 @@ int main()
     auto t = time(nullptr);
     auto tm = *std::gmtime(&t);
 
+    dbc::log("TEST 1 of the logging thing");
+    dbc::check(stats_out.good(), "Error opening stats.csv file.");
+    dbc::pre("simple test", [&]() { return stats_out.good(); });
+
     while(getline(cin, line)) {
       print("{}\n", line);
       if(regex_match(line, err, err_re)) {
@@ -34,5 +40,10 @@ int main()
     }
 
     stats_out.close();
+    dbc::post("a post test", [&]() { return !stats_out.is_open(); });
     return 0;
+  } catch(dbc::Error &err) {
+    print("ERROR: {}\n", err.message);
+    return 1;
+  }
 }