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Make defaults work on generic types #14

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Make defaults work on generic types #14

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23 changes: 20 additions & 3 deletions src/constructor/defaults.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -34,16 +34,30 @@ macro defaults*(genFlags: static set[DefaultFlag], tdef: untyped): untyped =
objDef = objectDef(tdef).copy() # This is just the object definiton (type Obj = object ...)
name = $objDef.name
innerIdent = genSym(nskType, ident = "Inner") # Inner type identificator
innerIdentTypedesc = newTree(nnkBracketExpr, ident("typedesc"), innerIdent) # typedesc[InnerType]
procIdentBase =
if tdef[2].kind == nnkRefTy:
"new"
else:
"init"
emptyNode = newEmptyNode()
innerIdentGeneric = newTree(nnkBracketExpr, innerIdent) # This is innerIdent with the generic parameters of objDef
procGenericParams = newTree(nnkGenericParams) # These are the generic params for the init/new procedures

# Here we collect all the names for the generic params [A, B: int = 1, C] -> [A, B, C]
for identdef in objDef.genericParams:
procGenericParams.add NimNode identdef
for name in identdef.names:
innerIdentGeneric.add NimNode name

let
# Inner//Inner[T]
innerIdent2 = # I know, horrible name
if procGenericParams.len > 0: innerIdentGeneric
else: innerIdent
innerIdentTypedesc = newTree(nnkBracketExpr, ident("typedesc"), innerIdent2) # typedesc[InnerType]

var
params = @[innerIdent] # First parameter is the return type
params = @[innerIdent2] # First parameter is the return type
constrParams = params # Object constructor parameters, first param is the constructor type
typeProcIdent = ident(procIdentBase)
procIdent = ident(procIdentBase & name)
Expand Down Expand Up @@ -72,7 +86,10 @@ macro defaults*(genFlags: static set[DefaultFlag], tdef: untyped): untyped =

let newTypeProc = newProc(typeProcIdent, params, objCStr)

# This procedure checks for instantiation errors
newProc[2] = procGenericParams
newTypeProc[2] = procGenericParams

# This procedure checks for instantiation errors when defTypeConstr or defBothConstr
let checkProc = newProc(genSym(nskProc, "checker"), body = newTree(nnkDiscardStmt, newCall(ident(procIdentBase), innerIdentTypedesc)))

var body = newStmtList(newTree(nnkTypeSection, NimNode objDef))
Expand Down