std.conv - custom string to struct conversion ?

[Douglas Petterson]

Is there a way to convert a string to a struct, similarly to the 
conversion of a struct to a custom string representation ?

The following code works fine when using format("%s",C) or 
to!string(C):

     struct sCustomConv
     {
         string toString()
         {
             return "My custom representation";
         }
     }

     sCustomConv C;
     string MyBackup = to!string(C);

But I can't find which class operator must be overloaded (or more 
simply how-to) to make this possible:

     C = to!sCustomConv(MyBackup);

Thx.