c++ - Type trait to identify types that can be read/written in binary form -

is there type trait (or concept) identify types following safe?

template <typename t> std::enable_if_t<std::some_type_trait<t>::value> write(std::ostream &os,const t &x)   { os.write(reinterpret_cast<const char *>(&x),sizeof(t)); }  template <typename t> std::enable_if_t<std::some_type_trait<t>::value> read(std::istream &is,t &x)   { is.read(reinterpret_cast<char *>(&x),sizeof(t)); } 

i’m thinking of classes containing pod excluding pointers (but not arrays). standardlayouttypes without pointers. neither want constrain objects trivialtype nor triviallycopyable.

sorry if i’m inaccurate. know little of data representation.

given 1^st parameter of s, read method:

extracts characters , stores them successive locations of character array first element pointed s

so real question is: if have initialized object writing string of bytes it's address, valid?

this concept of value representation. , value representation of trivially copyable types such that:

copying bytes occupied object in storage sufficient produce object same value

thus want ensure object trivially copyable isn't per standard concept can succinctly defined as:

• every copy constructor trivial or deleted
• every move constructor trivial or deleted
• every copy assignment operator trivial or deleted
• every move assignment operator trivial or deleted
• at least 1 copy constructor, move constructor, copy assignment operator, or move assignment operator non-deleted
• trivial non-deleted destructor

the spirit of assertion @ least 1 trivial initializer exists object boils down these requirements of trivially copyable type, it's non-static members, , of it's base classes:

1. it's given trivial initializer is, or behaves as, corresponding default intializer
2. it has no virtual methods
3. it has no members of volatile-qualified type

as far requirement of trivial destructor:

• the destructor not user-provided (meaning, either implicitly declared, or explicitly defined defaulted on first declaration)
• the destructor not virtual (that is, base class destructor not virtual)
• all direct base classes have trivial destructors
• all non-static data members of class type (or array of class type) have trivial destructors

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having defined means trivially copyable type, impossible "type trait or concept" determine whether of these requirements met in cases, example: type defines trivial initializer signature matches default initializer may or may not trivially copyable contingent on code initializes type in initializers body; such type, way determine if it's trivially copyable human inspection of initializer. if willing tighten requirements is detectable, is_trivially_copyable guarantee type trivially copyable.