`readprops` can not read files where the top level is an array

[fhagemann]

PropDicts can read this file:

# filename: propdicts.yaml
test:
  - value: 5
  - value: 6

readprops("propdict.yaml")

PropDict with 1 entry:
  :test => Dict{Any, Any}[Dict("value"=>5), Dict("value"=>6)]

However, it cannot read this:

# filename: array.yaml
- value: 5
- value: 6

readprops("array.yaml")

ERROR: MethodError: no method matching substitute_vars!(::Vector{Dict{Any, Any}}, ::Dict{String, String}; use_env::Bool, ignore_missing::Bool, recursive::Bool)
The function `substitute_vars!` exists, but no method is defined for this combination of argument types.

Closest candidates are:
  substitute_vars!(::AbstractDict, ::Dict{String, String}; use_env, ignore_missing, recursive)
   @ PropDicts ~/.julia/packages/PropDicts/2ofWJ/src/varsubst.jl:142
  substitute_vars!(::AbstractDict; ...)
   @ PropDicts ~/.julia/packages/PropDicts/2ofWJ/src/varsubst.jl:142

Stacktrace:
 [1] readprops(filename::String; subst_pathvar::Bool, subst_env::Bool, trim_null::Bool)
   @ PropDicts ~/.julia/packages/PropDicts/2ofWJ/src/propdict.jl:238
 [2] readprops(filename::String)
   @ PropDicts ~/.julia/packages/PropDicts/2ofWJ/src/propdict.jl:224
 [3] top-level scope
   @ REPL[5]:1

One use case where this might be relevant is for example validity files.

Should this be supported in PropDicts?

[oschulz]

Should this be supported in PropDicts?

It's not expected to work, currently . But we could add it.

[fhagemann]

I think the only reason not to add it would be that it would make readprops type-unstable (I guess now it always returns a PropDict)

[oschulz]

I think the only reason not to add it would be that it would make readprops type-unstable (I guess now it always returns a PropDict)

Good point. I think that would be Ok, PropDict itself is not really type stable, after all.

[fhagemann]

Nice, then it would be good to assign someone for this.