C#•3y ago

❔ Create new instance of type unknown at runtime?

Say I have a base class,

abstract class Letter

abstract class Letter

with child classes

, and

.

If I have a variable:

Letter myLetter

Letter myLetter

which is of unknown type (can be any of

, or

, the only guarantee is it's a child of

Letter

Letter

), how can I create a new instance of whatever class

myLetter

myLetter

is?

I need to create a new instance (must call default constructor as well) of whatever

myLetter

myLetter

is and store it in another variable (say

myLetter2

myLetter2

)

Angius•8/1/23, 10:36 PM

So, basically,

ShillelaghOP•8/1/23, 10:37 PM

Yes

Angius•8/1/23, 10:39 PM

Not gonna lie, I wonder why you'd need to do that, but aight

Angius•8/1/23, 10:39 PM

The one and only way I can think of is reflections

ShillelaghOP•8/1/23, 10:39 PM

Ah, I figured

Angius•8/1/23, 10:40 PM

should work

MODiX•8/1/23, 10:41 PM

Angius

REPL Result: Success

Result: bool

Compile: 531.005ms | Execution: 44.365ms | React with ❌ to remove this embed.

Angius•8/1/23, 10:41 PM

Yeah, seems to work file

AAngius Not gonna lie, I wonder why you'd need to do that, but aight

ShillelaghOP•8/1/23, 10:41 PM

Wondering as well if there was another way. In reality I have a reagent clasd which stores properties of the reagent including amount. When I move reagent from one container to another I need to remove the correct quantity from one container (changing its amount variable) and then add a new reagent instance of whatever type the reagent instance is from the first container, set the amount properly and store it I another container

Angius•8/1/23, 10:43 PM

Uh, ca't you just do

JP•8/1/23, 10:43 PM

So you have

And you need to be able to represent a change of state to:

Correct?

AAngius Uh, ca't you just do ```cs containerOne.Reagents.Add(containerTwo.Reagents[0]); ...

ShillelaghOP•8/1/23, 10:44 PM

If I move 100% of the reagent yes, otherwise a new reagent instance is necessary.

JJP So you have ``` ContainerA | Reagent1(30mg) ContainerB | -- ``` And you need to ...

ShillelaghOP•8/1/23, 10:44 PM

Yes

JP•8/1/23, 10:44 PM

This sounds like your reagents should not be C# types

ShillelaghOP•8/1/23, 10:45 PM

Wuh oh

JP•8/1/23, 10:45 PM

I'd have one Reagent type, which has an enum value-ed member , and an amount.

Angius•8/1/23, 10:45 PM

Or should be stored differently, although maybe I'm thinking too much in database terms to be introducing many-to-many lol

JP•8/1/23, 10:49 PM

what happens if you put 2 of the same reagent into a container?

ShillelaghOP•8/1/23, 10:52 PM

Whenever a reagent is added a method, which adds their quantities together

JP•8/1/23, 10:55 PM

my quick sketch, might be useful, might not be. It's here :P

JJP my quick sketch, might be useful, might not be. It's here :P ```csharp public e...

ShillelaghOP•8/1/23, 11:02 PM

Nice. Yes what I have going on is very similar. My previous version used a class in place of an enum (since different reagents have special properties) but was otherwise identical. Previously all combining was done in an addreagent method as well, but I never made on for the slightly newer version

JP•8/1/23, 11:03 PM

have special properties

What do these properties look like? (Literal C# properties?)

ShillelaghOP•8/1/23, 11:04 PM

No, methods that define how a reagent might react with another. The base class has a react method, overridden by a child.

JP•8/1/23, 11:05 PM

Aha, I think I have the solution

JP•8/1/23, 11:05 PM

one moment, sketching

JP•8/1/23, 11:08 PM

Each reagent can be responsible for creating the new one:

ShillelaghOP•8/1/23, 11:10 PM

Ah true

ShillelaghOP•8/1/23, 11:10 PM

That would work

JP•8/1/23, 11:12 PM

If the is always the same for all, can do some generic stuff:

JP•8/1/23, 11:12 PM

alright, I stop spam now haha

ShillelaghOP•8/1/23, 11:14 PM

A generic is clever there

ShillelaghOP•8/1/23, 11:14 PM

Nw, thanks for the help

Accord•8/2/23, 11:26 PM

Was this issue resolved? If so, run

/close

/close

otherwise I will mark this as stale and this post will be archived until there is new activity.