Add support for value(::AbstractArray) without broadcasting (#4010)

Author: araujoms

src/variables.jl

@@ -2698,11 +2698,12 @@ function dual(::GenericVariableRef)
     )
 end
 
-function value(::AbstractArray{<:AbstractJuMPScalar})
-    return error(
-        "`JuMP.value` is not defined for collections of JuMP types. Use" *
-        " Julia's broadcast syntax instead: `JuMP.value.(x)`.",
-    )
+function value(var_value::Function, Q::AbstractArray{<:AbstractJuMPScalar})
+    return value.(var_value, Q)
+end
+
+function value(Q::AbstractArray{<:AbstractJuMPScalar}; result::Int = 1)
+    return value.(Q; result)
 end
 
 # Fallback. See JuMP#3775

test/test_generate_and_solve.jl

@@ -692,4 +692,30 @@ function test_value_hermitian()
     return
 end
 
+function test_value_array()
+    inner = MOI.Utilities.MockOptimizer(
+        MOI.Utilities.UniversalFallback(MOI.Utilities.Model{Float64}()),
+    )
+    model = direct_model(inner)
+    @variable(model, x[i in 1:2], start = 3 - i)
+    @variable(
+        model,
+        y[i in 1:2, j in 1:2] in ComplexPlane(),
+        start = i + im * j
+    )
+    @test_throws OptimizeNotCalled value(x)
+    @test_throws OptimizeNotCalled value(y)
+    @test value(start_value, x) == [2, 1]
+    @test value(start_value, y) == [1+im 1+2im; 2+im 2+2im]
+    optimize!(model)
+    MOI.set(inner, MOI.TerminationStatus(), MOI.OPTIMAL)
+    idx = index.(all_variables(model))
+    MOI.set.(inner, MOI.VariablePrimal(), idx, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+    @test value(x) == [1, 2]
+    @test value(y) == [3+4im 7+8im; 5+6im 9+10im]
+    @test_throws MOI.ResultIndexBoundsError value(x; result = 2)
+    @test_throws MOI.ResultIndexBoundsError value(y; result = 2)
+    return
+end
+
 end  # module

test/test_nlp.jl

@@ -1270,20 +1270,6 @@ function test_multivariate_NLconstraint_is_valid()
     return
 end
 
-function test_broadcast_error_NLexpression()
-    model = Model()
-    @variable(model, x)
-    @NLexpression(model, expr, sin(x))
-    @test_throws(
-        ErrorException(
-            "`JuMP.value` is not defined for collections of JuMP types. " *
-            "Use Julia's broadcast syntax instead: `JuMP.value.(x)`.",
-        ),
-        value([x, x]),
-    )
-    return
-end
-
 function test_interval_errors()
     model = Model()
     @variable(model, x)

test/test_variable.jl

@@ -747,17 +747,6 @@ function test_dual_variable()
     return
 end
 
-function test_value_containers()
-    model = Model()
-    @variable(model, x[1:2])
-    exception = ErrorException(
-        "`JuMP.value` is not defined for collections of JuMP types. Use " *
-        "Julia's broadcast syntax instead: `JuMP.value.(x)`.",
-    )
-    @test_throws exception value(x)
-    return
-end
-
 function test_get_variable_coefficient()
     m = Model()
     x = @variable(m, x)