enum behaivor. another rehash of the topic

[Marco Leise]

Am Sun, 15 Dec 2013 02:16:39 +0100
schrieb "Joseph Rice" <ricejm01 at gmail.com>:

> While I must first Admit I'm new to D.   However; I have been a 
> C/C++ programmer for 15 years. I am excited about D.  One of the 
> features I love is being able to access my legacy code.    But 
> there are some cases were a complete re-write/re-factor to D 
> makes sense. I've come to it very frustrating code that has been 
> stable for years now needs to be changed because of a language 
> quirk.  The main selling point about D is C/C++ is almost the 
> same syntax,  I see potential in D to replace C/C++.
> 
> I've noticed that enum behavior is dramatically different.  This 
> is my opinion,  but I see this as a flaw in D.  Again let me 
> repeat, My opinion.   While I understand D's approach to enum's.  
> It is a hard pill to swallow for an experienced programmer.
> 
> The D compiler should know the type of the enum from the symbol.  
> You should not have to type the NAME.element when doing a 
> comparison or assignment.   Declaring an enum FOO { one, two, 
> three} should be the same as declaring a new type.   So that when 
> you declare `FOO bar;` in code, assignment and comparison of 
> `bar`  should know what bar is comprised of because it is of type 
> enum FOO.   Therefore anything of type enum FOO can only comprise 
> of the values 'one', 'two', or 'three'.
> 
> I've prepared 3 examples, a C, C++, and Finally D.  All 
> essentially the same code.  You will notice that the D version, 
> has some vast differences. For example you can not define an enum 
> and declare the variable all at once.   This gets me to the 
> annoying part.  assigning and Comparing.
> 
> jrice at Wayland:~/prj/enum_example$ gcc -o enum_c enum.c
> jrice at Wayland:~/prj/enum_example$ g++ -o enum_cpp enum.cpp
> jrice at Wayland:~/prj/enum_example$ dmd enum.d
> jrice at Wayland:~/prj/enum_example$ ./enum_c
> It's test1
> jrice at Wayland:~/prj/enum_example$ ./enum_cpp
> It's test1
> jrice at Wayland:~/prj/enum_example$ ./enum
> It's test1
> jrice at Wayland:~/prj/enum_example$ cat enum.c
> #include <stdio.h>
> 
> void main() {
> 	enum TEST {
> 		test1=0,
> 		test2
> 	} test;
> 
> 	test = test1;
> 	
> 	switch (test) {
> 		case test1:
> 			printf("It's test1\n");
> 			break;
> 		case test2:
> 			printf("It's test2\n");
> 			break;
> 		default:
> 		break;
> 	}
> }
> jrice at Wayland:~/prj/enum_example$ cat enum.cpp
> #include <iostream>
> using namespace std;
> 
> int main() {
> 	enum TEST {
> 		test1=0,
> 		test2
> 	} test;
> 
> 	test = test1;
> 	
> 	switch (test) {
> 		case test1:
> 			cout << "It's test1" << endl;
> 			break;
> 		case test2:
> 			cout << "It's test2" << endl;
> 			break;
> 		default:
> 		break;
> 	}
> 	return 0;
> }
> jrice at Wayland:~/prj/enum_example$ cat enum.d
> import std.stdio;
> 
> void main() {
> 	enum TEST {
> 		test1=0,
> 		test2
> 	};
> 
> 	TEST test = TEST.test1;
> 	
> 	switch (test) {
> 		case TEST.test1:
> 			writeln("It's test1");
> 			break;
> 		case TEST.test2:
> 			writeln("It's test2");
> 			break;
> 		default:
> 		break;
> 	}
> }
> 
> So as you can see, D is just awkward, and it becomes tedious 
> especially if you have many many many values in the enum.
 

void main() {
	enum TEST {
		test1,
		test2
	}

	TEST test = TEST.test1;
	
	with(TEST) final switch (test) {
		case test1:
			writeln("It's test1");
			break;
		case test2:
			writeln("It's test2");
			break;
	}
}


-- 
Marco