Problem with external constant for the macro @constraint

[newptcai]

I just tried the example in the document. This is what I get.

julia> a = 3;
julia> C = @constraint x^2 + y^2 <= $a
ERROR: LoadError: TypeError: in Interval, in T, expected T<:Real, got Type{Expr}
Stacktrace:
 [1] ..(::Float64, ::Expr) at /home/xinca341/.julia/packages/IntervalArithmetic/W4cqS/src/intervals/intervals.jl:136
 [2] parse_comparison(::Expr) at /home/xinca341/.julia/packages/IntervalConstraintProgramming/ta93g/src/separator.jl:88
 [3] @constraint(::LineNumberNode, ::Module, ::Expr, ::Any) at /home/xinca341/.julia/packages/IntervalConstraintProgramming/ta93g/src/separator.jl:185 (repeats 2 times)
in expression starting at REPL[57]:1

[dpsanders]

Oops, that seems to have broken at some point "recently".
cc @Yashcodes

[dpsanders]

Try without the variable:

C = @constraint x^2 + y^2 <= 3

[dpsanders]

Here's an alternative:

julia> using ModelingToolkit

julia> @variables x y
(x, y)

julia> a = 3
3

julia> C = Separator(x^2 + y^2 < a)
Separator:
  - variables: x, y
  - expression: x ^ 2 + y ^ 2 == [-∞, 3]

[newptcai]

The alternative works, but is this a bug?

julia> C = Separator(x^2+y^2<=a)
ERROR: MethodError: no method matching iterate(::Nothing)
Closest candidates are:
  iterate(::Core.SimpleVector) at essentials.jl:600
  iterate(::Core.SimpleVector, ::Any) at essentials.jl:600
  iterate(::ExponentialBackOff) at error.jl:218
  ...
Stacktrace:
 [1] indexed_iterate(::Nothing, ::Int64) at ./tuple.jl:66
 [2] Separator(::Array{Any,1}, ::Operation) at /home/xinca341/.julia/packages/IntervalConstraintProgramming/ta93g/src/separator.jl:199
 [3] Separator(::Operation) at /home/xinca341/.julia/packages/IntervalConstraintProgramming/ta93g/src/separator.jl:203
 [4] top-level scope at REPL[77]:1

[dpsanders]

That is a detail of ModelingToolkit.jl:
SciML/ModelingToolkit.jl#101

For now use < instead of <=.

[lucaferranti]

With the @constraint macro, the interpolation works if the variable is on the left-hand side. The following seems to work on 1.4 and 1.5

julia> a = 3
3

julia> C = @constraint x^2 + y^2 - $a <= 0
Separator:
  - variables: x, y
  - expression: (x ^ 2 + y ^ 2) - 3 ∈ [-∞, 0]

[hisacro]

With the @constraint macro, the interpolation works if the variable is on the left-hand side. The following seems to work on 1.4 and 1.5

julia> a = 3
3

julia> C = @constraint x^2 + y^2 - $a <= 0
Separator:
  - variables: x, y
  - expression: (x ^ 2 + y ^ 2) - 3 ∈ [-∞, 0]

this stopped working on julia 1.9

a = 3
C = @constraint x^2 + y^2 - $a <= 0

ERROR: UndefVarError: `a` not defined
Stacktrace:
 [1] top-level scope
   @ ~/.julia/packages/IntervalConstraintProgramming/HiqgO/src/separator.jl:127