• Gary Willoughby (13/13) May 28 2013 Why does the following snippet print:
• bearophile (10/23) May 28 2013 It looks like a compiler bug :-) (Enums of strings are not well
• John Colvin (12/25) May 28 2013 I don't really know what the correct way of doing this is. There
• John Colvin (3/4) May 28 2013 or alternatively .name of course. Either way there should be a
• Jesse Phillips (11/11) May 28 2013 I do not believe this is a bug. You should be able to print the
• bearophile (5/6) May 28 2013 You are right, I was wrong. writeln is meant to write the name of
• Kenji Hara (17/30) May 28 2013 This is not compiler bug, it is an intended behavior of writefln.

"Gary Willoughby" <dev kalekold.net> writes:

Why does the following snippet print:

"Started name revision" instead of "Started my-app 1.0a"?

import std.stdio;

enum application : string
{
	name     = "my-app",
	revision = "1.0a",
}

void main(string[] arguments)
{
	writefln("Started %s %s", application.name, 
application.revision);
}

"bearophile" <bearophileHUGS lycos.com> writes:

Gary Willoughby:

 Why does the following snippet print:

 "Started name revision" instead of "Started my-app 1.0a"?

 import std.stdio;

 enum application : string
 {
 	name     = "my-app",
 	revision = "1.0a",
 }

 void main(string[] arguments)
 {
 	writefln("Started %s %s", application.name, 
 application.revision);
 }

It looks like a compiler bug :-) (Enums of strings are not well 
supported. enums were invented mostly for integral types.) If 
it's not already in Bugzilla then I suggest to add it there.

By the way, in D enum names as "application" usually start with 
an upper case ("Application"), and the name of the main array is 
usually "args". Sticking with common practices is better, unless 
you have (uncommon) real reasons to do something different.

Bye,
bearophile

"John Colvin" <john.loughran.colvin gmail.com> writes:

On Tuesday, 28 May 2013 at 11:49:25 UTC, Gary Willoughby wrote:
 Why does the following snippet print:

 "Started name revision" instead of "Started my-app 1.0a"?

 import std.stdio;

 enum application : string
 {
 	name     = "my-app",
 	revision = "1.0a",
 }

 void main(string[] arguments)
 {
 	writefln("Started %s %s", application.name, 
 application.revision);
 }

I don't really know what the correct way of doing this is. There 
really ought to be a property .value of enums.

The stringof property will return what you want, although 
annoyingly with quotation marks around it ([1 .. $-1] on the end 
will clear that up of course). For types other than string it 
returns cast(application)value as a string, which is not 
particularly helpful.

BTW this only happens with named enums, anonymous enums print the 
value not the name.


I don't know how much any of this is intended behaviour and how 
much is just by chance.

"John Colvin" <john.loughran.colvin gmail.com> writes:

On Tuesday, 28 May 2013 at 12:16:51 UTC, John Colvin wrote:
 There really ought to be a property .value of enums.

or alternatively .name of course. Either way there should be a 
way to choose whether you want the name or the value.

"Jesse Phillips" <Jesse.K.Phillips+D gmail.com> writes:

I do not believe this is a bug. You should be able to print the 
value by casting to string. (to!() will not work as it will 
provide the same results)

Usually enumeration values are not descriptive for how they 
should be used. And when printing to the screen it is usually for 
debugging or some other task where a meaningful name would be 
better.

String enum's are a little different since there value can be 
fairly descriptive. But still they usually are not descriptive 
about how they should be used. And it would be odd for enum of 
int to print the enum name while string enum to print the value.

"bearophile" <bearophileHUGS lycos.com> writes:

On Tuesday, 28 May 2013 at 14:35:22 UTC, Jesse Phillips wrote:
 I do not believe this is a bug.

You are right, I was wrong. writeln is meant to write the name of 
enums and not their contents.

Bye,
bearophile

"Kenji Hara" <k.hara.pg gmail.com> writes:

On Tuesday, 28 May 2013 at 11:49:25 UTC, Gary Willoughby wrote:
 Why does the following snippet print:

 "Started name revision" instead of "Started my-app 1.0a"?

 import std.stdio;

 enum application : string
 {
 	name     = "my-app",
 	revision = "1.0a",
 }

 void main(string[] arguments)
 {
 	writefln("Started %s %s", application.name, 
 application.revision);
 }

This is not compiler bug, it is an intended behavior of writefln.

writefln always print the name for named enum members.

enum E1 { a, b }
writefln("%s", E1.a);    // prints a

enum E2 { a = 10, b = 20 }
writefln("%s", E2.a);    // prints a

enum E3 : string { a = "aaa", b = "bbb" }
writefln("%s", Ee.a);    // prints a

If you want to make a set of compile time values, you can write 
as follows:

struct application  // or class
{
     enum name     = "my-app",
          revision = "1.0a";
}

Kenji Hara