Implementation of varname_and_value_leaves that can handle containers

[torfjelde]

We often find ourselves in situations where we need to flatten both varnames and values together to produce a "simple" map varname => value where value isa Real rather than a Vector or NamedTuple, e.g. in construction of MCMCChains.Chains.

For this we have the function varname_and_value_leaves(vn, x) which takes in a VarName and some value x, e.g. a Vector, and returns an iterator over pairs of VarName and Real as desired:

DynamicPPL.jl/src/utils.jl

Lines 970 to 985 in 0e40bd0

	"""
	varname_and_value_leaves(vn::VarName, val)
	Return an iterator over all varname-value pairs that are represented by `vn` on `val`.
	# Examples
	```jldoctest varname-and-value-leaves
	julia> using DynamicPPL: varname_and_value_leaves
	julia> foreach(println, varname_and_value_leaves(@varname(x), 1:2))
	(x[1], 1)
	(x[2], 2)
	julia> foreach(println, varname_and_value_leaves(@varname(x[1:2]), 1:2))
	(x[1:2][1], 1)
	(x[1:2][2], 2)

But very often we actually want to do this for a container of multiple VarNames, e.g. OrderedDict or NamedTuple. Currently we just do this "by hand" every time we need this, but that seems unnecessary.

Sooo this PR just adds an implementation for OrderedDict and NamedTuple (which are the most common containers we work with, though the impl is very trivial) so we don't have to do this by hand everywhere.

Ref: #663 where we would benefit from this in the tests.

[coveralls]

Pull Request Test Coverage Report for Build 11049301945

Details

• 4 of 4 (100.0%) changed or added relevant lines in 1 file are covered.
• 19 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.03%) to 77.511%

---

Files with Coverage Reduction	New Missed Lines	%
src/model.jl	1	88.46%
src/threadsafe.jl	18	49.57%

Totals
Change from base Build 10992907511:	0.03%
Covered Lines:	2716
Relevant Lines:	3504

---

💛 - Coveralls

[mhauru]

Looks good, just a question about whether this could be defined more broadly.

[torfjelde]

Thanks @mhauru !