What is #pragma implicit and #pragma downcast

In the process of automatically converting my 2.6 project into 3.0, Unity has added

#pragma implicit
#pragma downcast

to all my scripts. Does anyone know why and what these do? The shipped help docs don't say anything about these.

Thanks!

 

#pragma implicit allows you to implicitly declare variables when using #pragma strict.

Code (csharp):

1. #pragma strict
2. foo = 5; // no!
3.  
4. #pragma strict
5. var foo = 5; // yes!
6.  
7. #pragma strict
8. #pragma implicit
9. foo = 5; // yes!

#pragma downcast allows casting from a super type to a sub type when using #pragma strict.

Code (csharp):

1. #pragma strict
2. var go : GameObject;
3. var clone : GameObject = Instantiate(go); // no!  Instantiate returns Object, not GameObject
4.  
5. #pragma strict
6. #pragma downcast
7. var go : GameObject;
8. var clone : GameObject = Instantiate(go); // yes!
9.  
10. #pragma strict
11. var go : GameObject;
12. var clone : GameObject = Instantiate(go) as GameObject; // yes!

The #pragma strict in Unity 2.6 wasn't as strict, so it was essentially using downcast and implicit.

--Eric

 

?

Doesn't #pragma implicit nullify #pragma strict ?

 

Eh? No....

Code (csharp):

1. #pragma strict
2.  
3. function Start () {
4.     var foo = GetComponent(Transform);
5.     foo.position.x = 100.0;  // no!  Can't use dynamic typing with #pragma strict!
6. }

#pragma implicit wouldn't have any effect there. (Might want to use #pragma downcast though, depending on how you fix the dynamic typing.)

--Eric

 

What's wrong with this line ? We just assign 100.0 to the x variable of a transform.position :-|

 

"foo" has no type, i.e. is not explicitly a Transform.

 

Try the code and see what the error is.

Actually no, GetComponent returns Component, so "foo" is of type Component, which has no position variable.

--Eric

 

So what is the best procedure then? To use #pragma downcast, or to adjust the line to not return a Component but a Transform? Code like the following (from the documentation) no longer work without having #pragma downcast.

Code (csharp):

1. var mesh : Mesh = new Mesh ();
2. GetComponent(MeshFilter).mesh = mesh;

So, without using a #pragma downcast, how would I tweak that so I don't get the error about Component not having a .mesh attribute?

 

Code (csharp):

1. (GetComponent(MeshFilter) as MeshFilter).mesh = mesh;

Or use generics:

Code (csharp):

1. GetComponent.<MeshFilter>().mesh = mesh;

--Eric

 

Hey guys, just wondering, in your sections of example code, you have #pragma strict on multiple lines. I thought it only had to be stated once at the top of each script?

 

Those are meant to be separate examples.

--Eric

 

Got it. thought I might have been missing something there for a sec

 

how would be this for enabling script, for example I want to disable/enable script "chack" attached to game object. I have such line:

PHP:

child.gameObject.GetComponent("chack").enabled=true;

and it gives me such error: 'enabled' is not a member of 'UnityEngine.Component'. when I write:

PHP:

child.gameObject.GetComponent.<"chack">().enabled=true;

it gives me this error: Unexpected token: chack.

 

heh, it doesn't need quotes
child.gameObject.GetComponent.<chack>().enabled=true;