support for shadowing of global variabls (#122)

Author: Krastanov

CHANGELOG.md

@@ -1,5 +1,9 @@
 # News
 
+## v1.0.2 - 2025-02-07
+
+- Support shadowing of globals, e.g. `@resumable function f(); a=a+1; end;` where `a` is already an existing global.
+
 ## v1.0.1 - 2024-11-23
 
 - Better macro hygiene (e.g. for better support in Pluto.jl) 

Project.toml

@@ -5,7 +5,7 @@ license = "MIT"
 desc = "C# sharp style generators a.k.a. semi-coroutines for Julia."
 authors = ["Ben Lauwens and volunteer maintainers"]
 repo = "https://github.com/JuliaDynamics/ResumableFunctions.jl.git"
-version = "1.0.1"
+version = "1.0.2"
 
 [deps]
 Logging = "56ddb016-857b-54e1-b83d-db4d58db5568"

src/utils.jl

@@ -247,8 +247,8 @@ end
 # We solve this problem by renaming all variables.
 #
 # We use a ScopeTracker type to keep track of the things that are already
-# renamned. It is basically just a Vector{Dict{Symbol, Symbol}},
-# representing a stack, where the top records the renamend variables in the
+# renamed. It is basically just a Vector{Dict{Symbol, Symbol}},
+# representing a stack, where the top records the renamed variables in the
 # current scope.
 #
 # The renaming is done as follows. If we encounter an assignment of the form
@@ -261,7 +261,7 @@ end
 # This is done in lookup_lhs!. Note that some construction, like `let`, create
 # a new variable in a new scope. This is handled by the `new` keyword.
 #
-# For any other symbol y (which is not the left hand side of an assignmetn),
+# For any other symbol y (which is not the left hand side of an assignment),
 # there are the following two cases:
 #   1) y has been seen before in some scope. Then we replace y accordingly.
 #   2) y has not been seen before, then we don't rename it.
@@ -467,13 +467,14 @@ function scoping(expr::Expr, scope)
       return quote $(res...) end
     end
 
-    # the LHS is a symbol or a tuple of symbols
-    expr.args[1] = lookup_lhs!(expr.args[1], scope)
-
-    # now transform the RHS, this can be anything
+    # first transform the RHS (this can be anything) to check for shadowing of globals
     for i in 2:length(expr.args)
       expr.args[i] = scoping(expr.args[i], scope)
     end
+
+    # only then deal with the LHS (it is a symbol or a tuple of symbols)
+    expr.args[1] = lookup_lhs!(expr.args[1], scope)
+
     return expr
   end
   if expr.head === :macrocall

test/test_globals.jl

@@ -0,0 +1,46 @@
+using ResumableFunctions
+using Test
+
+a = 1
+g() = 1
+h(x) = x+1
+
+@resumable function f1()
+    b = a
+    b = b+1
+    @yield b
+end
+
+@test collect(f1()) == [2]
+
+@resumable function f2()
+    a = a
+    a = a+1
+    @yield a
+end
+
+@test collect(f2()) == [2]
+
+@resumable function f3()
+    g = g()
+    g = g+1
+    @yield g
+end
+
+@test collect(f3()) == [2]
+
+@resumable function f4()
+    a = h(a)
+    a = a+1
+    @yield a
+end
+
+@test collect(f4()) == [3]
+
+@resumable function f5()
+    g = h(g())
+    g = g+1
+    @yield g
+end
+
+@test collect(f5()) == [3]