From 649dc8efd0f2c67801b1a97b3ee7f506ab890b16 Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Mon, 23 May 2022 16:20:51 +0200
Subject: [PATCH] Allow types that are equivalent to Confirmable

Allows ?TransactionResponse, Option[TransactionResponse] etc
to be used instead of Confirmable.
---
 ethers/contract.nim          | 57 +++++++++++++-----------------------
 testmodule/test.nimble       |  1 +
 testmodule/testContracts.nim |  3 +-
 3 files changed, 24 insertions(+), 37 deletions(-)

diff --git a/ethers/contract.nim b/ethers/contract.nim
index c786381..ca92810 100644
--- a/ethers/contract.nim
+++ b/ethers/contract.nim
@@ -102,35 +102,35 @@ func isConstant(procedure: NimNode): bool =
       return true
   false
 
-func isTxResponse(returntype: NimNode): bool =
-  return returntype.eqIdent($ Confirmable)
-
 func addContractCall(procedure: var NimNode) =
   let contract = procedure[3][1][0]
   let function = $basename(procedure[0])
   let parameters = getParameterTuple(procedure)
   let returntype = procedure[3][0]
-  # procedure[5] =
-  #   quote:
-  #     static: checkReturnType(type(result))
+
+  func call: NimNode =
+    if returntype.kind == nnkEmpty:
+      quote:
+        await call(`contract`, `function`, `parameters`)
+    else:
+      quote:
+        return await call(`contract`, `function`, `parameters`, `returntype`)
+
+  func send: NimNode =
+    if returntype.kind == nnkEmpty:
+      quote:
+        discard await send(`contract`, `function`, `parameters`)
+    else:
+      quote:
+        when typeof(result) isnot Confirmable:
+          {.error: "unexpected return type, missing {.view.} or {.pure.} ?".}
+        return await send(`contract`, `function`, `parameters`)
+
   procedure[6] =
     if procedure.isConstant:
-      if returntype.kind == nnkEmpty:
-        quote:
-          await call(`contract`, `function`, `parameters`)
-      else:
-        quote:
-          return await call(`contract`, `function`, `parameters`, `returntype`)
+      call()
     else:
-      # When ?TransactionResponse is specified as the return type of contract
-      # method, it allows for contract transactions to be awaited on
-      # confirmations
-      if returntype.isTxResponse:
-        quote:
-          return await send(`contract`, `function`, `parameters`)
-      else:
-        quote:
-          discard await send(`contract`, `function`, `parameters`)
+      send()
 
 func addFuture(procedure: var NimNode) =
   let returntype = procedure[3][0]
@@ -143,20 +143,6 @@ func addAsyncPragma(procedure: var NimNode) =
     procedure[4] = newNimNode(nnkPragma)
   procedure[4].add ident("async")
 
-func checkReturnType(procedure: NimNode) =
-  let returntype = procedure[3][0]
-  if returntype.kind != nnkEmpty:
-    # Do not throw exception for methods that have a TransactionResponse
-    # return type as that is needed for .wait
-    if returntype.isTxResponse:
-      return
-
-    if not procedure.isConstant:
-      const message =
-        "only contract functions with {.view.} or {.pure.} " &
-        "can have a return type"
-      error(message, returntype)
-
 macro contract*(procedure: untyped{nkProcDef|nkMethodDef}): untyped =
 
   let parameters = procedure[3]
@@ -164,7 +150,6 @@ macro contract*(procedure: untyped{nkProcDef|nkMethodDef}): untyped =
 
   parameters.expectMinLen(2) # at least return type and contract instance
   body.expectKind(nnkEmpty)
-  procedure.checkReturnType()
 
   var contractcall = copyNimTree(procedure)
   contractcall.addContractCall()
diff --git a/testmodule/test.nimble b/testmodule/test.nimble
index c7c6c46..2ebc1d7 100644
--- a/testmodule/test.nimble
+++ b/testmodule/test.nimble
@@ -4,6 +4,7 @@ description = "Tests for Nim Ethers library"
 license = "MIT"
 
 requires "asynctest >= 0.3.0 & < 0.4.0"
+requires "questionable >= 0.10.3 & < 0.11.0"
 
 task test, "Run the test suite":
   exec "nimble install -d -y"
diff --git a/testmodule/testContracts.nim b/testmodule/testContracts.nim
index d805e46..26e6646 100644
--- a/testmodule/testContracts.nim
+++ b/testmodule/testContracts.nim
@@ -1,5 +1,6 @@
 import std/json
 import pkg/asynctest
+import pkg/questionable
 import pkg/stint
 import pkg/ethers
 import ./hardhat
@@ -19,7 +20,7 @@ method totalSupply*(erc20: Erc20): UInt256 {.base, contract, view.}
 method balanceOf*(erc20: Erc20, account: Address): UInt256 {.base, contract, view.}
 method allowance*(erc20: Erc20, owner, spender: Address): UInt256 {.base, contract, view.}
 method transfer*(erc20: Erc20, recipient: Address, amount: UInt256) {.base, contract.}
-method mint(token: TestToken, holder: Address, amount: UInt256): Confirmable {.base, contract.}
+method mint(token: TestToken, holder: Address, amount: UInt256): ?TransactionResponse {.base, contract.}
 
 suite "Contracts":