Simplify implementation of Algorithm(::Symbol) (#224)

Author: odow

src/NLopt.jl

@@ -63,14 +63,12 @@ end
 Base.convert(::Type{nlopt_algorithm}, a::Algorithm) = nlopt_algorithm(Int(a))
 Base.convert(::Type{Algorithm}, r::nlopt_algorithm) = Algorithm(Int(r))
 
-const _SYMBOL_TO_ALGORITHM = Dict(Symbol(i) => i for i in instances(Algorithm))
-
-function Algorithm(name::Symbol)
-    algorithm = get(_SYMBOL_TO_ALGORITHM, name, nothing)
-    if algorithm === nothing
-        throw(ArgumentError("unknown algorithm $name"))
+function Algorithm(name::Symbol)::Algorithm
+    algorithm = nlopt_algorithm_from_string("$name")
+    if UInt32(algorithm) == 0xffffffff
+        throw(ArgumentError("unknown algorithm: $name"))
     end
-    return algorithm::Algorithm
+    return algorithm
 end
 
 # enum nlopt_result

test/C_API.jl

@@ -75,8 +75,8 @@ function test_issue_156_no_error()
 end
 
 function test_invalid_algorithms()
-    @test_throws ArgumentError("unknown algorithm BILL") Algorithm(:BILL)
-    @test_throws ArgumentError("unknown algorithm BILL") Opt(:BILL, 420)
+    @test_throws ArgumentError("unknown algorithm: BILL") Algorithm(:BILL)
+    @test_throws ArgumentError("unknown algorithm: BILL") Opt(:BILL, 420)
     return
 end