Hi guys,

I'm trying to read a string from a text file which contains a value of an enumeration like:

enum MyEnum : string {
   Entry_1 = "abc",
   Entry_2 = "def",
   Entry_3 = "ghi",
}

Stream s = new File("myFile.ext", FileMode.In);
uint len;
s.read(len);
string entry = cast(string) s.readString(len);
s.close();

writeln(mixin("MyEnum." ~ entry));

myFile.ext may contain:
...
Entry_2
Entry_1
Entry_2
Entry_3
...

But mixin's are for compile time only... is there any chance to do this or do I've to use another method (like if/else or switch/case):

if (entry == "Entry_1") ...
else if (entry == "Entry_2") ...
...

Thanks a lot!

You could generate the if/else-chain, lookup table, etc. via metaprogramming to save you the typing and code duplication (probably a foreach over std.traits.EnumMembers will be involved).

David


On 7/7/11 11:23 PM, nrgyzer wrote:
> Hi guys,
>
> I'm trying to read a string from a text file which contains a value of an enumeration like:
>
> enum MyEnum : string {
>     Entry_1 = "abc",
>     Entry_2 = "def",
>     Entry_3 = "ghi",
> }
>
> Stream s = new File("myFile.ext", FileMode.In);
> uint len;
> s.read(len);
> string entry = cast(string) s.readString(len);
> s.close();
>
> writeln(mixin("MyEnum." ~ entry));
>
> myFile.ext may contain:
> ...
> Entry_2
> Entry_1
> Entry_2
> Entry_3
> ...
>
> But mixin's are for compile time only... is there any chance to do this or do I've to use another method (like if/else or switch/case):
>
> if (entry == "Entry_1") ...
> else if (entry == "Entry_2") ...
> ...
>
> Thanks a lot!

Am 07.07.2011 23:23, schrieb nrgyzer:
> Hi guys,
>
> I'm trying to read a string from a text file which contains a value of an enumeration like:
>
> enum MyEnum : string {
>     Entry_1 = "abc",
>     Entry_2 = "def",
>     Entry_3 = "ghi",
> }
>
> Stream s = new File("myFile.ext", FileMode.In);
> uint len;
> s.read(len);
> string entry = cast(string) s.readString(len);
> s.close();
>
> writeln(mixin("MyEnum." ~ entry));
>
> myFile.ext may contain:
> ...
> Entry_2
> Entry_1
> Entry_2
> Entry_3
> ...
>
> But mixin's are for compile time only... is there any chance to do this or do I've to use another method (like if/else or switch/case):
>
> if (entry == "Entry_1") ...
> else if (entry == "Entry_2") ...
> ...
>
> Thanks a lot!

Metaprogramming is the keyword but you don't have to do it yourself. Just use std.conv.to!MyEnum(string_without_the prefix).

Mafi

== Auszug aus Mafi (mafi@example.org)'s Artikel
> Am 07.07.2011 23:23, schrieb nrgyzer:
> > Hi guys,
> >
> > I'm trying to read a string from a text file which contains a
value of an enumeration like:
> >
> > enum MyEnum : string {
> >     Entry_1 = "abc",
> >     Entry_2 = "def",
> >     Entry_3 = "ghi",
> > }
> >
> > Stream s = new File("myFile.ext", FileMode.In);
> > uint len;
> > s.read(len);
> > string entry = cast(string) s.readString(len);
> > s.close();
> >
> > writeln(mixin("MyEnum." ~ entry));
> >
> > myFile.ext may contain:
> > ...
> > Entry_2
> > Entry_1
> > Entry_2
> > Entry_3
> > ...
> >
> > But mixin's are for compile time only... is there any chance to
do this or do I've to use another method (like if/else or switch/
case):
> >
> > if (entry == "Entry_1") ...
> > else if (entry == "Entry_2") ...
> > ...
> >
> > Thanks a lot!
> Metaprogramming is the keyword but you don't have to do it yourself.
> Just use std.conv.to!MyEnum(string_without_the prefix).
> Mafi

Thanks Mafi, exactly what I'm looking for :)