use more explicit constructors

memory/buffer/circular.hpp

@@ -27,7 +27,7 @@ namespace util { namespace memory { namespace buffer {
     public:
         using value_type = char;
 
-        circular (size_t bytes);
+        explicit circular (size_t bytes);
         ~circular ();
 
         circular (const circular&) = delete;

pool.hpp

@@ -41,7 +41,9 @@ namespace util {
             size_t m_size;
 
         public:
+            explicit
             pool (unsigned int _capacity);
+
             ~pool ();
 
             // Data management

posix/dir.hpp

@@ -46,7 +46,7 @@ namespace util { namespace posix {
 
     struct dir {
     public:
-        dir (const char *path);
+        explicit dir (const char *path);
         ~dir ();
 
         operator DIR* (void);