Merge pull request #1128 from JuliaOpt/bl/nosolver

Remove solver concept and AbstractSolverInstanceAttribute

src/JuMP.jl

@@ -35,7 +35,7 @@ export
     PSDCone,
 # Functions
     # Model related
-    setobjectivesense, setsolver,
+    setobjectivesense,
     writeLP, writeMPS,
     #addSOS1, addSOS2,
     solve,
@@ -76,10 +76,6 @@ const BINREF = MOICON{MOI.SingleVariable,MOI.ZeroOne}
 
 @MOIU.instance JuMPInstance (ZeroOne, Integer) (EqualTo, GreaterThan, LessThan, Interval) (Zeros, Nonnegatives, Nonpositives, SecondOrderCone, RotatedSecondOrderCone, PositiveSemidefiniteConeTriangle) () (SingleVariable,) (ScalarAffineFunction,ScalarQuadraticFunction) (VectorOfVariables,) (VectorAffineFunction,)
 
-# dummy solver
-type UnsetSolver <: MathOptInterface.AbstractSolver
-end
-
 ###############################################################################
 # Model class
 # Keeps track of all model and column info
@@ -141,7 +137,6 @@ mutable struct Model <: AbstractModel
     # internal solver instance object
     solverinstance
     # Solver+option object from MPB or MOI
-    solver
     solverinstanceattached::Bool
     # callbacks
     callbacks
@@ -172,11 +167,8 @@ mutable struct Model <: AbstractModel
     # dictionary keyed on an extension-specific symbol
     ext::Dict{Symbol,Any}
     # Default constructor
-    function Model(;solver=UnsetSolver(), simplify_nonlinear_expressions::Bool=false)
+    function Model(; simplify_nonlinear_expressions::Bool=false)
         # TODO need to support MPB also
-        if !isa(solver,MOI.AbstractSolver)
-            error("solver argument ($solver) must be an AbstractSolver")
-        end
         m = new()
         # TODO make pretty
         m.instance = JuMPInstance{Float64}()
@@ -192,7 +184,6 @@ mutable struct Model <: AbstractModel
         m.objbound = 0.0
         m.objval = 0.0
         m.solverinstance = nothing
-        m.solver = solver
         m.solverinstanceattached = false
         m.callbacks = Any[]
         m.solvehook = nothing
@@ -404,18 +395,6 @@ dualstatus(m::Model) = MOI.get(m, MOI.DualStatus())
 # setobjective(::Model, ::Symbol, x::AbstractArray) =
 #     error("in setobjective: array of size $(_size(x)) passed as objective; only scalar objectives are allowed")
 
-"""
-    setsolver(m::Model, solver::MathOptInterface.AbstractSolver)
-
-Change the solver which will be used for the next call to `solve()`, discarding the current internal model if present.
-"""
-function setsolver(m::Model, solver::MOI.AbstractSolver)
-    m.solver = solver
-    m.solverinstance = nothing
-    m.solverinstanceattached = false
-    nothing
-end
-
 # # Deep copy the model
 # function Base.copy(source::Model)
 #

src/solverinterface.jl

@@ -10,9 +10,9 @@ Attach the JuMP model `m` to a new solver instance. All instance data is transfe
 and while the solver instance remains attached, all modifications to the JuMP model are immediately mirrored
 in the solver instance. See also `isattached()` and `detach()`.
 """
-function attach(m::Model)
+function attach(m::Model, solverinstance::MOI.AbstractSolverInstance)
     @assert !m.solverinstanceattached
-    m.solverinstance = MOI.SolverInstance(m.solver)
+    m.solverinstance = solverinstance
     solvervariables = MOI.addvariables!(m.solverinstance, numvar(m)) # TODO numvar shouldn't return unsigned int
 
     m.variabletosolvervariable = Dict{MOIVAR,MOIVAR}()
@@ -60,24 +60,24 @@ function detach(m::Model)
 end
 
 """
-    canget(m::JuMP.Model, attr::MathOptInterface.AbstractSolverInstanceAttribute)::Bool
+    canget(m::JuMP.Model, attr::MathOptInterface.AbstractInstanceAttribute)::Bool
 
 Return `true` if one may query the attribute `attr` from the solver instance attached to the JuMP model,
 false if not.
 Throws an error if no solver instance is currently attached.
 """
-function MOI.canget(m::Model, attr::MOI.AbstractSolverInstanceAttribute)
+function MOI.canget(m::Model, attr::MOI.AbstractInstanceAttribute)
     @assert m.solverinstanceattached
     return MOI.canget(m.solverinstance, attr)
 end
 
 """
-    get(m::JuMP.Model, attr::MathOptInterface.AbstractSolverInstanceAttribute)
+    get(m::JuMP.Model, attr::MathOptInterface.AbstractInstanceAttribute)
 
 Return the value of the attribute `attr` from the solver instance attached to the JuMP model.
 Throws an error if no solver instance is currently attached.
 """
-function MOI.get(m::Model, attr::MOI.AbstractSolverInstanceAttribute)
+function MOI.get(m::Model, attr::MOI.AbstractInstanceAttribute)
     @assert m.solverinstanceattached
     return MOI.get(m.solverinstance, attr)
 end
@@ -91,9 +91,7 @@ function solve(m::Model;
         return m.solvehook(m)
     end
 
-    if !m.solverinstanceattached
-        attach(m)
-    end
+    @assert m.solverinstanceattached
     MOI.optimize!(m.solverinstance)
 
     empty!(m.variableresult)

test/lp.jl

@@ -5,13 +5,14 @@
         # st   x + y <= 1   (x + y - 1 ∈ Nonpositives)
         #       x, y >= 0   (x, y ∈ Nonnegatives)
 
-        m = Model(solver=CSDPSolver(printlevel=0))
+        m = Model()
         @variable(m, x >= 0.0)
         @variable(m, y >= 0.0)
         @objective(m, Min, -x)
 
         @constraint(m, x + y <= 1)
 
+        JuMP.attach(m, CSDPInstance(printlevel=0))
         JuMP.solve(m)
 
         @test JuMP.isattached(m)