Change how nested interpolations are displayed (omitting unrequired parenthesis).

Add test for nested quotes and interpolations.

Correct small bug preventing correct display of "t[a b;]".

Update metaprogramming docs to better reflect changes in how quoting and unquoting get displayed.

Author: ChiaffarelliMarco

base/show.jl

@@ -1171,6 +1171,7 @@ function show_unquoted(io::IO, ex::Expr, indent::Int, prec::Int)
                 head = :hcat
             end
             args = args[2:end]
+            nargs = nargs - 1
         end
         op, cl = expr_parens[head]
         if head === :vcat || head === :bracescat
@@ -1382,9 +1383,8 @@ function show_unquoted(io::IO, ex::Expr, indent::Int, prec::Int)
         elseif isa(args[1], Symbol) &&
                startswith(string(args[1]::Symbol), "@") &&
                endswith(string(args[1]::Symbol), "_str")
-            m = match(r"^Symbol\(\"@(.+)_str\"\)$",
-                      repr(args[1]))
-            print(io, m.captures[1], "\"", args[3], "\"")
+            s = repr(args[1])
+            print(io, s[10:prevind(s,end,6)], "\"", args[3], "\"")
             if nargs == 4
                 print(io, args[4])
             end
@@ -1473,7 +1473,8 @@ function show_unquoted(io::IO, ex::Expr, indent::Int, prec::Int)
     elseif (head === :& || head === :$) && nargs == 1
         print(io, head)
         a1 = args[1]
-        parens = (isa(a1,Expr) && a1.head !== :tuple) || (isa(a1,Symbol) && isoperator(a1))
+        parens = (isa(a1,Expr) && (a1.head !== :tuple && a1.head !== :$)) ||
+                 (isa(a1,Symbol) && isoperator(a1))
         parens && print(io, "(")
         show_unquoted(io, a1)
         parens && print(io, ")")

doc/src/manual/metaprogramming.md

@@ -126,6 +126,9 @@ julia> Symbol(:var,'_',"sym")
 :var_sym
 ```
 
+Note that to use `:` syntax, the symbol's name must be a valid identifier.
+Otherwise the `Symbol(str)` constructor must be used.
+
 In the context of an expression, symbols are used to indicate access to variables; when an expression
 is evaluated, a symbol is replaced with the value bound to that symbol in the appropriate [scope](@ref scope-of-variables).
 
@@ -265,7 +268,7 @@ quote
 end
 ```
 
-Notice that the result contains `Expr(:$, :x)`, which means that `x` has not been
+Notice that the result contains `$x`, which means that `x` has not been
 evaluated yet.
 In other words, the `$` expression "belongs to" the inner quote expression, and
 so its argument is only evaluated when the inner quote expression is:
@@ -293,7 +296,7 @@ quote
 end
 ```
 
-Notice that `:(1 + 2)` now appears in the result instead of the symbol `:x`.
+Notice that `(1 + 2)` now appears in the result instead of the symbol `x`.
 Evaluating this expression yields an interpolated `3`:
 
 ```jldoctest interp1
@@ -550,7 +553,7 @@ julia> macro twostep(arg)
 @twostep (macro with 1 method)
 
 julia> ex = macroexpand(Main, :(@twostep :(1, 2, 3)) );
-I execute at parse time. The argument is: $(Expr(:quote, :((1, 2, 3))))
+I execute at parse time. The argument is: :((1, 2, 3))
 ```
 
 The first call to [`println`](@ref) is executed when [`macroexpand`](@ref) is called. The

test/show.jl

@@ -767,7 +767,7 @@ test_mt(show_f5, "show_f5(A::AbstractArray{T,N}, indices::Vararg{$Int,N})")
 @test_repr "T[a,b]"
 @test_repr "T[a;b;c]"
 @test_repr "T[a b]"
-# @test_repr "T[a b;]" #= don't now what to expect from this =#
+@test_repr "T[a b;]"
 @test_repr "T[a b c]"
 @test_repr "T[a b; c d]"
 
@@ -797,7 +797,14 @@ end"""
         \$a + \$b
     end
 end""")) ==
-":(macro m(a, b)\n      #= none:2 =#\n      quote\n          #= none:3 =#\n          \$a + \$b\n      end\n  end)"
+"""
+:(macro m(a, b)
+      #= none:2 =#
+      quote
+          #= none:3 =#
+          \$a + \$b
+      end
+  end)"""
 @test repr(Meta.parse(
 """macro m(a, b)
     :(\$a + \$b)
@@ -806,6 +813,30 @@ end""")) ==
 @test repr(Expr(:macro, Expr(:call, :m, :x), Expr(:quote, Expr(:call, :+, Expr(:($), :x), 1)))) ==
 ":(macro m(x)\n      :(\$x + 1)\n  end)"
 
+# nested quotes and interpolations
+@test repr(Meta.parse(
+"""quote
+    quote
+        \$\$x
+    end
+end""")) ==
+"""
+:(quote
+      #= none:2 =#
+      quote
+          #= none:3 =#
+          \$\$x
+      end
+  end)"""
+@test_repr """
+quote
+    #= none:2 =#
+    quote
+        #= none:3 =#
+        \$\$x
+    end
+end"""
+
 # string interpolation, if this is what the comment in test_rep function
 # definition talk about
 @test repr(Expr(:string, "foo", :x, "bar")) == ":(\"foo\$(x)bar\")"