Call a function with arguments from a Blob value

qwertytrewq · January 1, 2025, 2:47am

In Motoko, let f be a shared method and b be arguments of f encoded as a blob (e.g. by to_candid). How to call f with these arguments, if the types of f arguments are unknown (so, we can’t use from_candid).

skilesare · January 3, 2025, 1:30pm

github.com

dfinity/motoko-base/blob/c6331b0f236e13581b6b094a9b6442ffbc0b254c/src/ExperimentalInternetComputer.mo#L32


      
          /// let ledger = Principal.fromText("ryjl3-tyaaa-aaaaa-aaaba-cai");
          /// let method = "decimals";
          /// let input = ();
          /// type OutputType = { decimals : Nat32 };
          ///
          /// let rawReply = await IC.call(ledger, method, to_candid(input)); // serialized Candid
          /// let output : ?OutputType = from_candid(rawReply); // { decimals = 8 }
          /// ```
          ///
          /// [Learn more about Candid serialization](https://internetcomputer.org/docs/current/motoko/main/reference/language-manual#candid-serialization)
          public let call : (canister : Principal, name : Text, data : Blob) -> async (reply : Blob) = Prim.call_raw;
          
          /// Given computation, `comp`, counts the number of actual and (for IC system calls) notional WebAssembly
          /// instructions performed during the execution of `comp()`.
          ///
          /// More precisely, returns the difference between the state of the IC instruction counter (_performance counter_ `0`) before and after executing `comp()`
          /// (see [Performance Counter](https://internetcomputer.org/docs/current/references/ic-interface-spec#system-api-performance-counter)).
          ///
          /// NB: `countInstructions(comp)` will _not_ account for any deferred garbage collection costs incurred by `comp()`.
          ///
          /// Example:

qwertytrewq · January 3, 2025, 8:41pm

In my question, the name of the function f is unknown. Also, its canister is unknown. Only a shared function variable f is known.

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Call a function with arguments from a Blob value

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