[fastx adapter] change entrypoint type signature rules to accept `&mu… #144
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…t TxContext`
Previously, the adapter expected the last argument of an entrypoint to be an owned `TxContext`.
When playing with some example Move code, I realized that this makes entrypoint composition inconvenient. For example, say you
have the following entrypoints:
```
public fun main1(ctx: TxContext) { ... }
public fun main2(ctx: TxContext) { ... }
```
If you want to create a third entrypoint that composes `main1` and `main2` like so
```
public fun main_compose(ctx: TxContext) {
main1(ctx);
main2(ctx) // error: ctx moved on previously line
}
```
, this will not work.
Switching the entrypoint signature to use `&mut TxContext` instead solves this problem without otherwise changing the programming experience.
huitseeker
reviewed
Jan 9, 2022
Couple of reasons:
|
gdanezis
approved these changes
Jan 10, 2022
| // Input ref parameters we put in should be the same number we get out | ||
| debug_assert!(mutable_ref_objects.len() == mutable_ref_values.len()); | ||
| // Input ref parameters we put in should be the same number we get out, plus one for the &mut TxContext | ||
| debug_assert!(mutable_ref_objects.len() + 1 == mutable_ref_values.len()); |
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Ok, just to check: this is not a mutable object that our system will persist right? It is internal to the move call?
| // Input ref parameters we put in should be the same number we get out, plus one for the &mut TxContext | ||
| debug_assert!(mutable_ref_objects.len() + 1 == mutable_ref_values.len()); | ||
| // discard the &mut TxContext arg | ||
| mutable_ref_values.pop().unwrap(); |
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I think you just answered my question be poping and discarding. But then why return it at all?
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Ah ok, because the move call returns it.
huitseeker
approved these changes
Jan 10, 2022
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…t TxContext`
Previously, the adapter expected the last argument of an entrypoint to be an owned
TxContext.When playing with some example Move code, I realized that this makes entrypoint composition inconvenient. For example, say you have the following entrypoints:
If you want to create a third entrypoint that composes
main1andmain2like so, this will not work.
Switching the entrypoint signature to use
&mut TxContextinstead solves this problem without otherwise changing the programming experience.