It's more of a multi-part question,
I've been trying to read tuples using 'slurp', though later realised one of the types was an enum, I'm guessing that's what was the problem, which lead me down a whole rabbit hole.

- Can I directly read tuples using slurp? It doesnt seem to like slurp!TUPLE_ALIAS_HERE(etc

- Since slurp can read files into tuples, can I somehow tell slurp to name the fields?
(For example, I have `alias Instruction = Tuple!(OPERATION, "operation", int, "argument");`, but I'm not sure if it's possible to make slurp output one), or alternatively, can I define it's output tuple 'type'?

- If it's possible to make user types print in certain ways (https://wiki.dlang.org/Defining_custom_print_format_specifiers), is it possible to also read them back? Say using formattedRead or slurp or parse or even to? And if so, how does this work?

- Is it possible to read (formatted) data into enums, as for example I would like? I wouldnt be surprised if this question stands loose from the previous one, as it's not entirely the same situation.
I have an enum;
enum OPERATION {NOP, // Would like to read 'nop' hereto
		ACCUMULATE, // 'acc' likewise
		JUMP // and 'jmp'
		}

🤔I'm either asking a stupid question, asking it in a wrong way, or asking an important question. Clueless nontheless. . .

On 12/31/20 8:36 AM, Rekel wrote:
> 🤔I'm either asking a stupid question, asking it in a wrong way, or asking an important question. Clueless nontheless. . .

Your post was interesting to me but trying to duplicate your situation seemed difficult.

Can you describe it with a piece of code? If the code shows what the current undesired output is and what you want instead, perhaps we can find a solution.

Ali

On Thursday, 31 December 2020 at 18:19:54 UTC, Ali Çehreli wrote:
> Can you describe it with a piece of code? If the code shows what the current undesired output is and what you want instead, perhaps we can find a solution.

Regarding the enum part;
While trying to do this I noticed one cannot use either slurp or formattedRead to read enums, while it is possible to use formattedWrite and write to write them.
Strangely enough this was also mentioned in old issue '18051' (https://forum.dlang.org/thread/mailman.735.1512835762.9493.digitalmars-d-bugs@puremagic.com) which should have been resolved.

Example code;
```
import std.stdio;
import std.file : slurp;
import std.format;
import std.typecons;

enum Thing {
	A,
	B
}

void main() {
	File file = File("temp.txt", "r");
	foreach (line; file.byLine) {
		int integer;
		Thing thing;
		formattedRead!"%s %s"(line, integer, thing); // crashes with thing as Thing, works with thing as char.
		formattedWrite(stdout.lockingTextWriter, "%s %s\n", integer, thing);
	}
}
```

And regarding the rest,

I'm curious about reading back user types, without defining a new seperate method for it, such as structs, unions and tuples, (although I'm unsure to what extent tuples are really a user-defined-type).

The other thing just resolved itself;
I was wondering, as slurp kind of already reads tuples from files, whether or not it's possible to tell it what tuple you want it to read, instead of redefining a possibly previously aliased tuple.
It seems now I found a way to do just that . . . I honestly don't know why this went wrong before, must have made a mistake somewhere. This now works:

	alias Entry = Tuple!(int, "a", char, "b");
	Entry[] results = slurp!Entry("temp.txt", "%s %s");
	results.writeln;

Im actually kind of surprised it does, as nothing in the documentation seems to hint to me this makes sense, neither did I find any example like it elsewhere.