Implement printing

src/StructJuMP.jl

@@ -260,9 +260,11 @@ function JuMP.set_objective(m::StructuredModel, sense::MOI.OptimizationSense,
     m.objective_function = f
 end
 JuMP.objective_sense(m::StructuredModel) = m.objective_sense
-function JuMP.objective_function(m::StructuredModel, FT::Type)
-    m.objective_function isa FT || error("The objective function is not of type $FT")
-    m.objective_function
+JuMP.objective_function_type(model::StructuredModel) = typeof(model.objective_function)
+JuMP.objective_function(model::StructuredModel) = model.objective_function
+function JuMP.objective_function(model::StructuredModel, FT::Type)
+    model.objective_function isa FT || error("The objective function is not of type $FT")
+    model.objective_function
 end
 
 # Names
@@ -275,6 +277,30 @@ function JuMP.set_name(cref::StructuredConstraintRef, name::String)
     cref.model.connames[cref.idx] = name
 end
 
+# Show
+function JuMP.show_backend_summary(io::IO, model::StructuredModel) end
+function JuMP.show_objective_function_summary(io::IO, model::StructuredModel)
+    println(io, "Objective function type: ",
+            JuMP.objective_function_type(model))
+end
+function JuMP.objective_function_string(print_mode, model::StructuredModel)
+    return JuMP.function_string(print_mode, JuMP.objective_function(model))
+end
+_plural(n) = (isone(n) ? "" : "s")
+function JuMP.show_constraints_summary(io::IO, model::StructuredModel)
+    n = length(model.constraints)
+    print(io, "Constraint", _plural(n), ": ", n)
+end
+function JuMP.constraints_string(print_mode, model::StructuredModel)
+    strings = String[]
+    # Sort by creation order, i.e. ConstraintIndex value
+    constraints = sort(collect(model.constraints), by = c -> c.first.value)
+    for (index, constraint) in constraints
+        push!(strings, JuMP.constraint_string(print_mode, constraint))
+    end
+    return strings
+end
+
 include("BendersBridge.jl")
 
 end

test/printhook.jl

@@ -5,21 +5,38 @@ using StructJuMP
 @testset "printhook" begin
 
     numScen = 2
-    m = StructuredModel(num_scenarios=numScen)
+    parent = StructuredModel(num_scenarios=numScen)
 
-    @variable(m, 0 <= x <= 1)
-    @variable(m, 0 <= y <= 1)
+    @variable(parent, 0 <= x <= 1)
+    @variable(parent, 0 <= y <= 1)
 
-    @constraint(m, x + y == 1)
-    @objective(m, Min, x*x + y)
+    @constraint(parent, x + y == 1)
+    @objective(parent, Min, x*x + y)
 
     for i in 1:numScen
-        bl = StructuredModel(parent=m, id=i)
+        bl = StructuredModel(parent=parent, id=i)
         @variable(bl, w >= 0)
         @constraint(bl, w - x - y <= 1)
         @objective(bl, Min, w*w + w)
     end
 
-    str = string(m)
-    @test occursin("Child", str)
+    str = string(parent)
+    @test sprint(print, parent) == """
+Min x² + y
+Subject to
+ x + y = 1.0
+"""
+    @test sprint(show, parent) == """
+A JuMP Model
+Minimization problem with:
+Variables: 2
+Objective function type: GenericQuadExpr{Float64,StructJuMP.StructuredVariableRef}
+Constraint: 1
+Names registered in the model: x, y"""
+    @test sprint(show, "text/latex", parent) == """
+\$\$ \\begin{alignat*}{1}\\min\\quad & x^2 + y\\\\
+\\text{Subject to} \\quad & x + y = 1.0\\\\
+\\end{alignat*}
+ \$\$"""
+    #@test occursin("Child", str)
 end

test/runtests.jl

@@ -1,5 +1,5 @@
-#include("printhook.jl")
-#
+include("printhook.jl")
+
 include("benderstest.jl")
 #
 #include("farmer.jl")