I'm trying to test a piece of generic solidity code, I'm trying to figure out how to encode data properly for bytes parameters.
I have a function in a smart contract which looks like so:
function validateAdditionalCalldata(bytes calldata resolverOptions) external view;
function resolve(uint256 amountIn, bytes calldata resolverOptions) public override returns (uint256 amountOut) {
// Decode the additional calldata as a SwapResolverOptions struct
(SwapResolverOptions memory swapResolverOptions) = abi.decode(resolverOptions, (SwapResolverOptions));
return resolveImplementation(amountIn, swapResolverOptions);
}
This solidity code will generate code which takes in a PromiseOrValue<BytesLike>:
resolve(
amountIn: PromiseOrValue<BigNumberish>,
resolverOptions: PromiseOrValue<BytesLike>,
overrides?: Overrides & { from?: PromiseOrValue<string> }
): Promise<ContractTransaction>;
export type SwapResolverOptionsStruct = {
path: PromiseOrValue<BytesLike>;
deadline: PromiseOrValue<BigNumberish>;
amountIn: PromiseOrValue<BigNumberish>;
amountOutMinimum: PromiseOrValue<BigNumberish>;
inputTokenAddress: PromiseOrValue<string>;
targetAddress: PromiseOrValue<string>;
destinationAddress: PromiseOrValue<string>;
};
I'm wondering how I can encode a specific parameter so I can pass it along to ethers. In typescript I have a set of options that looks like this:
const resolverOptions: SwapResolverOptionsStruct = {
path: '0x00',
//This parameter will be removed in the next deployment
deadline: BigNumber.from(1000),
amountIn: BigNumber.from(100000000),
amountOutMinimum: BigNumber.from(0),
inputTokenAddress: WMATIC_MUMBAI,
destinationAddress: owner.address,
targetAddress: ADDRESS_ZERO,
};
I'm trying to encode this parameters in the following way:
import { defaultAbiCoder } from "#ethersproject/abi";
encodedResolverOptions = defaultAbiCoder.encode(
['SwapResolverOptionsStruct'],
[resolverOptions]
);
However when I try to encode it gets and error:
Error: invalid type (argument="type", value="SwapResolverOptionsStruct",
Note: in my paticular use case I cannot just encoded the whole function call.
I would like to pass my data to the validateAdditionalCalldata how ever the parameter is PromiseOrValue<BytesLike>
How can I encoded my resolverOptions so I can pass it as bytes?
I figured out a few way to do this. I'll list each one:
Resolve the type params using ethers and get function. (if there is a function which has your type in it)
const functionFragment = swapResolverInterface.getFunction("resolveImplementation");
encodedResolverOptions = defaultAbiCoder.encode(
[functionFragment.inputs[1]],
[resolverOptions]
);
Resolve it from an object and a method signature with parameter names:
encodedResolverOptions = defaultAbiCoder.encode(
["(bytes path,uint256 deadline,uint256 amountIn,uint256 amountOutMinimum,address inputTokenAddress,address destinationAddress,address targetAddress)"],
[resolverOptions]
);
Resolve it as an array from the method signature without names Note: this assumes the object was declared in the same order as the parameters, alternatively you can manually construct the array:
encodedResolverOptions = defaultAbiCoder.encode(
["(bytes,uint256,uint256,uint256,address,address,address)"],
[Object.values(resolverOptions)]
);
Related
For purposes of testing, it's useful to be able to "prepare" arguments to a function before executing such that the arguments can be checked against any result.
In JavaScript I can do this:
function testFunc ({id, count}) {
/* perform some operation */
return {id, count}
}
const args = {
id: 'someId',
count: Math.round(Math.random() * 10),
}
const res = testFunc({...args})
/* check that count is correct etc */
How do I achieve the same flexibility in Dart?
Map<String, dynamic> testFunc({String id, int count}) {
/* perform some operation */
return {
'id': id,
'count': count,
};
}
final args = /* erm? */
testFunc(args); /* hmmm? */
Am I trying to push the limits of a strongly typed language?
Dart is a statically checked language.
Using a value with an unknown run-time structure, like a map, as parameters makes it impossible to statically check the validity of the arguments.
Take the example:
var data = {#name: "hello", #age: 18};
Person(...data)
(Using symbols for referring to source names, same as Function.apply and noSuchMethod).
Here it looks easy to see that the map actually has a #name and an #age entry, but that's because the map is written as a literal right next to the application. That's the one situation where you don't actually need spread arguments, because you could just write the arguments directly.
In all actually useful cases, it's not possible to see statically which entries the map has, and which types the values are for each key. The type of the map, Map<Symbol, dynamic> is not strong enough to allow checking the call. You should just use Function.apply(Person, [], data) ... except that we (still) do not allow constructors as functions (#216).
If Dart had typed structs/named tuples, it might be possible to do:
// Static type is the named tuple type `(String name, int age)`
var data = (name: "name", age: 18);
var person = Person(...data);
At this point, the static type of data is specific enough to allow the call to be checked statically.
also this is issue in GitHub which I take the answer from
I'd like to store instances of models in a common provider using their classes or interfaces as a keys and then pop them up by class references. I have written some code:
class Provider {
public function new() { }
public function set<T:Any>(instance:T, ?type:Class<T>) {
if (type == null)
type = Type.getClass(instance);
if (type != null && instance != null)
map.set(type, instance);
}
public function get<T:Any>(type:Class<T>):Null<T> {
return cast map.get(type);
}
var map = new Map<Class<Any>, Any>();
}
...alas, it's even doesn't compile.
Probably I have to use qualified class name as a key rather than class/interface reference? But I'd like to keep neat get function design that takes type as argument and returns object just of type taken, without additional type casting.
Is it possible or should I change my approach to this problem?
The issue of using Class<T> as a Map key come up every so often, here is a related discussion. The naive approach of Map<Class<T>, T> fails to compile with something like this:
Abstract haxe.ds.Map has no #:to function that accepts haxe.IMap<Class<Main.T>, Main.T>`
There's several different approaches to this problem:
One can use Type reflection to obtain the fully qualified name of a class instance, and then use that as a key in a Map<String, T>:
var map = new Map<String, Any>();
var name = Type.getClassName(Main);
map[name] = value;
For convenience, you would probably want to have a wrapper that does this for you, such as this ClassMap implementation.
A simpler solution is to simply "trick" Haxe into compiling it by using an empty structure type ({}) as the key type. This causes ObjectMap to be chosen as the underlying map implementation.
var map = new Map<{}, Any>();
map[Main] = value;
However, that allows you to use things as keys that are not of type Class<T>, such as:
map[{foo: "bar"}] = value;
The type safety issues of the previous approach can be remedied by using this ClassKey abstract:
#:coreType abstract ClassKey from Class<Dynamic> to {} {}
This still uses ObjectMap as the underlying map implementation due to the to {} implicit cast. However, using a structure as a key now fails at compile time:
var map = new Map<ClassKey, Any>();
map[{foo: "bar"}] = value; // No #:arrayAccess function accepts arguments [...]
Now I'm using UIEventListener to add a clicker.When I write it in one file, it works all right.like this:
UIEventListener.Get(popButton).onClick = showPop;
But when I wrote it to two seprate files it gives me error.first file:
public class Adapter{
var grid:GameObject;
function addItems(data:List.<PrintItem>, prefab:GameObject, func:Function){
for(var i:int=0;i<data.Count;i++){
var gameObject:GameObject = NGUITools.AddChild(grid, prefab);
UIEventListener.Get(gameObject).onClick = func;
}
}
}
second file:
//I use the funtion like this
adapter.addItems(list, GO[0], hidePop);
//the hidePop is like this
var hidePop:Function = function(){
switchPopMenu(false);
};
when I run the unity give me the error
InvalidCastException: Cannot cast from source type to destination type.
Adapter.addItems (System.Collections.Generic.List`1 data,
UnityEngine.GameObject prefab, ICallable func) (at
Assets/Scripts/yhj/Tools/Adapter.js:12)
try using EventDelegate.Add(obj.onClick, func);. Direct assignment may cause certain issues.
How do I write a class that implements this TypeScript interface (and keeps the TypeScript compiler happy):
interface MyInterface {
(): string;
text2(content: string);
}
I saw this related answer:
How to make a class implement a call signature in Typescript?
But that only works if the interface only has the bare function signature. It doesn't work if you have additional members (such as function text2) to be implemented.
A class cannot implement everything that is available in a typescript interface. Two prime examples are callable signatures and index operations e.g. : Implement an indexible interface
The reason is that an interface is primarily designed to describe anything that JavaScript objects can do. Therefore it needs to be really robust. A TypeScript class however is designed to represent specifically the prototype inheritance in a more OO conventional / easy to understand / easy to type way.
You can still create an object that follows that interface:
interface MyInterface {
(): string;
text2(content: string);
}
var MyType = ((): MyInterface=>{
var x:any = function():string { // Notice the any
return "Some string"; // Dummy implementation
}
x.text2 = function(content:string){
console.log(content); // Dummy implementation
}
return x;
}
);
There's an easy and type-safe way to do this with ES6's Object.assign:
const foo: MyInterface = Object.assign(
// Callable signature implementation
() => 'hi',
{
// Additional properties
text2(content) { /* ... */ }
}
)
Intersection types, which I don't think were available in TypeScript when this question was originally asked and answered, are the secret sauce to getting the typing right.
Here's an elaboration on the accepted answer.
As far as I know, the only way to implement a call-signature is to use a function/method. To implement the remaining members, just define them on this function. This might seem strange to developers coming from C# or Java, but I think it's normal in JavaScript.
In JavaScript, this would be simple because you can just define the function and then add the members. However, TypeScript's type system doesn't allow this because, in this example, Function doesn't define a text2 member.
So to achieve the result you want, you need to bypass the type system while you define the members on the function, and then you can cast the result to the interface type:
//A closure is used here to encapsulate the temporary untyped variable, "result".
var implementation = (() => {
//"any" type specified to bypass type system for next statement.
//Defines the implementation of the call signature.
var result: any = () => "Hello";
//Defines the implementation of the other member.
result.text2 = (content: string) => { };
//Converts the temporary variable to the interface type.
return <MyInterface>result;
})(); //Invokes the closure to produce the implementation
Note that you don't need to use a closure. You could just declare your temporary variable in the same scope as the resulting interface implementation. Another option is to name the closure function to improve readability.
Here's what I think is a more realistic example:
interface TextRetriever {
(): string;
Replace(text: string);
}
function makeInMemoryTextRetriever(initialText: string) {
var currentText = initialText;
var instance: any = () => currentText;
instance.Replace = (newText: string) => currentText = newText;
return <TextRetriever>instance;
}
var inMemoryTextRetriever = makeInMemoryTextRetriever("Hello");
I'm working on finishing up my server for my first iPhone application, and I want to implement a simple little feature.
I would like to run a function (perhaps method as well), if another function returns a certain value after a certain waiting period. Fairly simple concept.... right?
Here's my basic foundation.
template <typename T,class TYP>
struct funcpar{
T (*function)(TYP);
TYP parameter;
funcpar(T (*func)(TYP),TYP param);
funcpar& operator=(const funcpar& fp);
};
The goal here is to be able to call funcpar::function(funcpar::parameter) to run the stored function and parameter, and not have to worry about anything else...
When I attempted to use a void* parameter instead of the template, I couldn't copy the memory as an object (because I didn't know what the end object was going to be, or the beginning for that matter) and when I tried multiple timers, every single object's parameter would change to the new parameter passed to the new timer... With the previous struct I have a
question:
Is it possible to make an all-inclusive pointer to this type of object inside a method of a class? Can I templatize a method, and not the whole class? Would it work exactly like a function template?
I have a managing class that holds a vector of these "jobs" and takes care of everything fairly well. I just don't know how to use a templatized function with the struct, or how to utilize templates on a single method in a class..
I'm also utilizing this in my custom simple threadpool, and that's working fairly well, and has the same problems...
I have another question:
Can I possibly store a function with a parameter before it's run? Something like toRun = dontrunmeyet(withThisParameter);? Is my struct even necessary?
Am I going about this whole thing incorrectly?
If this is overly ambiguous, I can set you up with my whole code for context
In order to create a class method that takes a template parameter, yes, it would work almost exactly like a function template. For example:
class A
{
public:
template<typename T>
void my_function(const T& value) { }
};
int main()
{
A test;
test.my_function(5);
return 0;
}
Secondly, for your structure, you can actually turn that into a functor-object that by overloading operator(), lets you call the structure as-if it were a function rather than having to actually call the specific function pointer members inside the structure. For instance, your structure could be re-written to look like this:
#include <iostream>
template <class ReturnType, class ParameterType>
class funcpar
{
private:
ReturnType (*function)(ParameterType);
ParameterType parameter;
public:
funcpar(ReturnType (*func)(ParameterType),ParameterType param):
function(func), parameter(param) {}
funcpar& operator=(const funcpar& fp);
//operator() overloaded to be a function that takes no arguments
//and returns type ReturnType
ReturnType operator() ()
{
return function(parameter);
}
};
int sample_func(int value)
{
return value + 1;
}
int main()
{
funcpar<int, int> test_functor(sample_func, 5);
//you can call any instance of funcpar just like a normal function
std::cout << test_functor() << std::endl;
return 0;
}
BTW, you do need the functor object (or your structure, etc.) in order to bind a dynamic parameter to a function before the function is called in C/C++ ... you can't "store" a parameter with an actual function. Binding a parameter to a function is actually called a closure, and in C/C++, creating a closure requires a structure/class or some type of associated data-structure you can use to bind a function with a specific parameter stored in memory that is used only for a specific instance of that function call.