🚀 go-pugleaf

Why are there no ifstream and ofstream constructors that take a
std::string rather than plain char* for the ``file name''?

The following `idiom' was, I think, often used (I use `S', and not `s', 
because this is not a proposed standard string class):

     cout >> "Enter file name -> ";
     String file_name;
     ifstream (file_name); // or: ofstream (file_name);

Declaring file_name as String, instead of char[file_name_length], 
one does not have to worry about reserving space for file name
(file_name_lengths are very different on different operating systems). 

The call to istream/ostream constructor is possible because String 
classes use to have:
    String::operator const char*() const
    
According to proposed standard one should write:
    ifstream (file_name.c_str());
because implicit conversion of string to const char* is not defined.

I agree that implicit conversion is (almost always) dangerous, and I
_do not_ propose to add conversion operator to string class. Instead, I
think that fstream classes, beside (or even instead of) constructors that
take const char*s, should have constructors that take strings.

In many C++ books we can read that plain C arrays (including char[]s 
and char*s) are to low level, and that we should use vector and string 
classes. Also, it is supposed that iostream classes and operators are 
`on the higher level of abstraction' than cstdio types and functions.
So, why do we have to manualy convert `high level constructs' to `low 
level constructs'?


Kresimir Fresl
Faculty of Civil Engineering, Zagreb, Croatia
fresl@master.grad.hr
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