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digitalmars.D.learn - Get type from string

reply DarkRiDDeR <DarkRiDDeRr ya.ru> writes:
Example:

class Bob {
  static void print ()
  {
    write("str");
  }
}
string name = "Bob";
__traits(getMember, Types.getType(name), "print")();

How can you implement "Types.getType(name)"? I do not know in 
advance what can be the class names.
Oct 28 2015
parent reply Adam D. Ruppe <destructionator gmail.com> writes:
On Wednesday, 28 October 2015 at 17:38:45 UTC, DarkRiDDeR wrote:

 string name = "Bob";
 __traits(getMember, Types.getType(name), "print")();

 How can you implement "Types.getType(name)"? I do not know in 
 advance what can be the class names.


You don't. __traits works at compile time, the string isn't known 
until run time.

If you can rewrite it to use an interface, you can make that work 
though.

interface Printable {
    void print();
}

class Bob : Printable {
    void print() { writeln("hey"); }
}

void main() {
    string name = "test.Bob"; // module name needed
    Printable printable = cast(Printable) Object.factory(name);
    if(printable is null) throw new Exception("bad class");

    printable.print();
}


Object.factory's neck is on the chopping block, but it might 
stick around anyway, and even if it goes away there will be an 
alternative. You could register classes in your own code, for 
example.

Regardless, this is a solution for now.
Oct 28 2015
parent reply DarkRiDDeR <DarkRiDDeRr ya.ru> writes:
Thank you! Is it possible to call a method from a string at run 
time?
Oct 28 2015
parent reply Adam D. Ruppe <destructionator gmail.com> writes:
On Wednesday, 28 October 2015 at 17:57:16 UTC, DarkRiDDeR wrote:

 Thank you! Is it possible to call a method from a string at run 
 time?


Yes, though you have to prepare code to do it. Again, I'd try to 
make it work on interfaces on some level.

The free sample chapter of my book 
https://www.packtpub.com/application-development/d-cookbook shows 
an example near the end of how to write that code. Basically, you 
loop over members at compile time and generate wrapper functions 
for them, which you then call based on a runtime string.
Oct 28 2015
parent DarkRiDDeR <DarkRiDDeRr ya.ru> writes:
On Wednesday, 28 October 2015 at 20:04:51 UTC, Adam D. Ruppe 
wrote:

 On Wednesday, 28 October 2015 at 17:57:16 UTC, DarkRiDDeR wrote:

 Thank you! Is it possible to call a method from a string at 
 run time?


 Yes, though you have to prepare code to do it. Again, I'd try 
 to make it work on interfaces on some level.

 The free sample chapter of my book 
 https://www.packtpub.com/application-development/d-cookbook 
 shows an example near the end of how to write that code. 
 Basically, you loop over members at compile time and generate 
 wrapper functions for them, which you then call based on a 
 runtime string.


I had the same idea to solve this problem. But the book is 
already good examples. Thank you.
Oct 29 2015