use the safer Object_createChild SBML methods.

[exaexa]

This depends on sbmlteam/libsbml#252 to be merged,
because some of the functions were actually not exposed to the C API.

Creating the members from the parent objects seems safer because all XML
metadata and versioning info gets automatically propagated. Also the code is a
bit shorter.

[exaexa]

(PS. obviously this won't work until the linked patch is in SBML_jll. :D )

[giordano]

I agree this pattern is a bit better, when it can be used 👍

[codecov]

Codecov Report

Merging #225 (d0284be) into master (8705bd1) will decrease coverage by 0.08%.
The diff coverage is 96.55%.

@@            Coverage Diff             @@
##           master     #225      +/-   ##
==========================================
- Coverage   93.76%   93.68%   -0.09%     
==========================================
  Files          10       10              
  Lines         754      728      -26     
==========================================
- Hits          707      682      -25     
+ Misses         47       46       -1     

Impacted Files	Coverage Δ
src/unitful.jl	100.00% <ø> (ø)
src/writesbml.jl	94.17% <96.55%> (-0.35%)	⬇️
src/interpret.jl	76.92% <0.00%> (+4.92%)	⬆️

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[exaexa]

when it can be used

Patchdozer disagrees. This will be used everywhere. :D

[giordano]

This PR also removes all uses of WRITESBML_PKG_DEFAULT_*

SBML.jl/src/writesbml.jl

Lines 4 to 7 in 9577bc1

	# Level/Version/Package version for the package
	const WRITESBML_PKG_DEFAULT_LEVEL = 3
	const WRITESBML_PKG_DEFAULT_VERSION = 1
	const WRITESBML_PKG_DEFAULT_PKGVERSION = 2

apart from where we get the URI of the fbc extension

SBML.jl/src/writesbml.jl

Lines 760 to 768 in 9577bc1

	uri = ccall(
	sbml(:SBMLExtension_getURI),
	Cstring,
	(VPtr, Cuint, Cuint, Cuint),
	sbmlext,
	WRITESBML_PKG_DEFAULT_LEVEL,
	WRITESBML_PKG_DEFAULT_VERSION,
	WRITESBML_PKG_DEFAULT_PKGVERSION,
	)

which sounds a good improvement in terms of consistency!

[exaexa]

Yeah that was the point. I kindof hope we'll eventually be able to spew out e.g. SBML L2V4 by just specifying the correct version and not filling in anything L3-specific into the sbml structure.

[exaexa]

now depends on JuliaPackaging/Yggdrasil#5224