Re: Safe cast

[Виталий Фадеев via Digitalmars-d-learn]

On Friday, 6 March 2020 at 12:35:29 UTC, Виталий Фадеев wrote:

Searching info for object casting with checking class type at runtime.

Like this:

class A
{
    //
}

class B
{
    int bVar;
}


unittest
{
    A a = new A();

    A x = cast( A )a;     // ok
    A x = cast( B )a;     // ok, but unsafe
    A x = safeCast( B )a; // throw exception
    A x = safeCast( A )a; // ok
}


Searching some like next:

T safeCast( CLS )( CLS o )
{
  ... // checking type of o
  ... // may be check ClassInfo...
  return T;
}

Has function like a safeCast() ?
Or other solution ? ...

I using now next code:

import std.stdio;

class Base {}

class A : Base {}
class B : Base {}


T safeCast( T, CLS )( CLS o )
{
        if ( typeid( o ) == typeid( T ) )
                return cast(T)o;
        else
                throw new Exception( "casting error" );
}


void main()
{       
    Base a = new A();

    A x1 = cast( A )a;      // ok
    B x2 = cast( B )a;      // ok, but unsafe
    B x3 = safeCast!B( a ); // throw exception
    A x4 = safeCast!A( a ); // ok
}