remove noise, document new getters/setters

Author: vyudu

docs/src/basics/Variable_metadata.md

@@ -54,6 +54,10 @@ using ModelingToolkit: t_nounits as t, D_nounits as D
 
 @variables i(t) [connect = Flow]
 @variables k(t) [connect = Stream]
+hasconnect(i)
+```
+```@example connect
+getconnect(k)
 ```
 
 ## Input or output
@@ -177,8 +181,35 @@ A variable can be marked `irreducible` to prevent it from being moved to an
 `observed` state. This forces the variable to be computed during solving so that
 it can be accessed in [callbacks](@ref events)
 
-```julia
+```@example metadata
 @variable important_value [irreducible = true]
+isirreducible(important_value)
+```
+
+## Units
+
+Units for variables can be designated using symbolic metadata. For more information, please see the [model validation and units](@ref units) section of the docs. Note that `getunit` is equivalent to `get_unit`. 
+
+```@example metadata
+@variable speed [unit=u"m/s"]
+hasunit(speed)
+```
+```@example metadata
+getunit(speed)
+```
+
+## Miscellaneous metadata
+
+User-defined metadata can be added using the `misc` metadata. This can be queried
+using the `hasmisc` and `getmisc` functions.
+
+```@example metadata
+@variables u [misc = :conserved_parameter] y [misc = [2, 4, 6]]
+hasmisc(u)
+```
+
+```@example metadata
+getmisc(y)
 ```
 
 ## Additional functions

src/variables.jl

@@ -8,7 +8,6 @@ struct VariableStatePriority end
 struct VariableMisc end
 Symbolics.option_to_metadata_type(::Val{:unit}) = VariableUnit
 Symbolics.option_to_metadata_type(::Val{:connect}) = VariableConnectType
-Symbolics.option_to_metadata_type(::Val{:noise}) = VariableNoiseType
 Symbolics.option_to_metadata_type(::Val{:input}) = VariableInput
 Symbolics.option_to_metadata_type(::Val{:output}) = VariableOutput
 Symbolics.option_to_metadata_type(::Val{:irreducible}) = VariableIrreducible
@@ -29,7 +28,7 @@ ModelingToolkit.dump_variable_metadata(p)
 """
 function dump_variable_metadata(var)
     uvar = unwrap(var)
-    vartype, name = Symbolics.getmetadata(uvar, VariableSource, (:unknown, :unknown))
+    variable_source, name = Symbolics.getmetadata(uvar, VariableSource, (:unknown, :unknown))
     type = symtype(uvar)
     if type <: AbstractArray
         shape = Symbolics.shape(var)
@@ -41,7 +40,6 @@ function dump_variable_metadata(var)
     end
     unit = getunit(uvar)
     connect = getconnect(uvar)
-    noise = getnoise(uvar) 
     input = isinput(uvar) || nothing
     output = isoutput(uvar) || nothing
     irreducible = isirreducible(var)
@@ -61,13 +59,12 @@ function dump_variable_metadata(var)
 
     meta = (
         var = var,
-        vartype,
+        variable_source,
         name,
         variable_type,
         shape,
         unit,
         connect,
-        noise,
         input,
         output,
         irreducible,
@@ -599,18 +596,3 @@ getunit(x) = get_unit(x)
 Check if the variable `x` has a unit.
 """
 hasunit(x) = getunit(x) !== nothing
-
-## Noise ======================================================================
-"""
-    getnoise(x)
-
-Get the noise type of variable `x`.
-"""
-getnoise(x) = getnoise(unwrap(x))
-getnoise(x::Symbolic) = Symbolics.getmetadata(x, VariableNoiseType, nothing)
-"""
-    hasnoise(x)
-
-Determine if variable `x` has a noise type.
-"""
-hasnoise(x) = getnoise(x) !== nothing

test/test_variable_metadata.jl

@@ -221,8 +221,10 @@ x = ModelingToolkit.setmisc(x, "okay")
 @variables x
 @test ModelingToolkit.getvariabletype(x) == ModelingToolkit.VARIABLE
 @test ModelingToolkit.dump_variable_metadata(x).variable_type == ModelingToolkit.VARIABLE
+@test ModelingToolkit.dump_variable_metadata(x).variable_source == :variables
 x = ModelingToolkit.toparam(x)
 @test ModelingToolkit.getvariabletype(x) == ModelingToolkit.PARAMETER
+@test ModelingToolkit.dump_variable_metadata(x).variable_source == :variables
 
 @parameters y
 @test ModelingToolkit.getvariabletype(y) == ModelingToolkit.PARAMETER