From 4758f9e97294ed62d50a1bcf8848b7714b76237a Mon Sep 17 00:00:00 2001
From: shenleban tongying <shenlebantongying@gmail.com>
Date: Mon, 11 Nov 2024 23:10:53 -0500
Subject: [PATCH] refactor: change `DEF_EX` macro's underlying implementation
 to template

---
 .clang-tidy      |  7 +++++-
 src/common/ex.hh | 65 ++++++++++++++++++++++++++++--------------------
 2 files changed, 44 insertions(+), 28 deletions(-)

diff --git a/.clang-tidy b/.clang-tidy
index 689c8aa3..1447cfea 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -17,7 +17,6 @@ Checks: >
   portability-*,
   readability-*,
   -bugprone-easily-swappable-parameters,
-  -bugprone-reserved-identifier,
   -cppcoreguidelines-owning-memory,
   -cppcoreguidelines-prefer-member-initializer,
   -cppcoreguidelines-pro-bounds-array-to-pointer-decay,
@@ -44,5 +43,11 @@ CheckOptions:
     value: 1
   - key: cppcoreguidelines-explicit-virtual-functions.IgnoreDestructors
     value: 1
+  - key: modernize-avoid-c-arrays.AllowStringArrays
+    value: 1
+  - key: cppcoreguidelines-avoid-c-arrays.AllowStringArrays
+    value: 1
+  - key: hicpp-avoid-c-arrays.AllowStringArrays
+    value: 1
 ...
 
diff --git a/src/common/ex.hh b/src/common/ex.hh
index 233f8c40..aec624b0 100644
--- a/src/common/ex.hh
+++ b/src/common/ex.hh
@@ -4,22 +4,17 @@
 #pragma once
 
 #include <string>
+#include <fmt/format.h>
+
+// clang-format off
 
 /// A way to declare an exception class fast
 /// Do like this:
 /// DEF_EX( exErrorInFoo, "An error in foo encountered", std::exception )
 /// DEF_EX( exFooNotFound, "Foo was not found", exErrorInFoo )
-
-#define DEF_EX( exName, exDescription, exParent ) \
-  class exName: public exParent                   \
-  {                                               \
-  public:                                         \
-    virtual const char * what() const noexcept    \
-    {                                             \
-      return ( exDescription );                   \
-    }                                             \
-    virtual ~exName() noexcept {}                 \
-  };
+#define DEF_EX( exName, exDescription, exParent )         \
+  constexpr static char ExStr_## exName[] = exDescription; \
+  using exName = defineEx< exParent, ExStr_## exName >;
 
 /// Same as DEF_EX, but takes a runtime string argument, which gets concatenated
 /// with the description.
@@ -29,20 +24,36 @@
 ///   throw exCantOpen( "example.txt" );
 ///
 ///   what() would return "can't open file example.txt"
+///
+#define DEF_EX_STR( exName, exDescription, exParent )     \
+  constexpr static char ExStr_## exName[] = exDescription; \
+  using exName = defineExStr< exParent, ExStr_## exName >;
 
-#define DEF_EX_STR( exName, exDescription, exParent )      \
-  class exName: public exParent                            \
-  {                                                        \
-    std::string value;                                     \
-                                                           \
-  public:                                                  \
-    explicit exName( std::string const & value_ ):         \
-      value( std::string( exDescription ) + " " + value_ ) \
-    {                                                      \
-    }                                                      \
-    virtual const char * what() const noexcept             \
-    {                                                      \
-      return value.c_str();                                \
-    }                                                      \
-    virtual ~exName() noexcept {}                          \
-  };
+// clang-format on
+
+template< typename ParentEx, const char * description >
+class defineEx: public ParentEx
+{
+public:
+  virtual const char * what() const noexcept
+  {
+    return description;
+  }
+};
+
+template< typename ParentEx, const char * description >
+class defineExStr: public ParentEx
+{
+public:
+  explicit defineExStr( std::string const & message_ ):
+    message( fmt::format( "{} {}", description, message_ ) )
+  {
+  }
+  virtual const char * what() const noexcept
+  {
+    return message.c_str();
+  }
+
+private:
+  std::string message;
+};