Creates special case for '=' processing (#253)

# Pull Request

- Fixes #252

### Changes description

- Adds special case for `=` as it is not recognizes as `language` in S4
dispatch

### Note to reviewers

the code with `=` call has a language type, but it tales priority
somewhere on the dispatcher and tries to dispatch with this class (`->`
doesn't have a problem)

---------

Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>

Author: averissimo

R/qenv-eval_code.R

@@ -98,7 +98,14 @@ setMethod("eval_code", signature = c("qenv", "expression"), function(object, cod
   if (length(srcref)) {
     eval_code(object, code = paste(attr(code, "wholeSrcref"), collapse = "\n"))
   } else {
-    Reduce(eval_code, init = object, x = code)
+    Reduce(function(u, v) {
+      if (inherits(v, "=") && identical(typeof(v), "language")) {
+        # typeof(`=`) is language, but it doesn't dispatch on it, so we need to
+        # explicitly pass it as first class of the object
+        class(v) <- unique(c("language", class(v)))
+      }
+      eval_code(u, v)
+    }, init = object, x = code)
   }
 })
 

tests/testthat/test-qenv_within.R

@@ -131,3 +131,21 @@ testthat::test_that("within run on qenv.error returns the qenv.error as is", {
 
   testthat::expect_identical(qe, qee)
 })
+
+testthat::describe("within run with `=`", {
+  testthat::it("single expression", {
+    q <- qenv()
+    q <- within(q, {
+      i = 1 # nolintr: assigment. styler: off.
+    })
+  })
+
+  testthat::it("multiple '=' expressions", {
+    q <- qenv()
+    q <- within(q, {
+      j = 2 # nolintr: assigment. styler: off.
+      i = 1 # nolintr: assigment. styler: off.
+    })
+    testthat::expect_equal(q$i, 1)
+  })
+})