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Fixes #114; Allow flattening options in objects #118

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Fixes #114; Allow flattening options in objects #118

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nitely Nov 1, 2025
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remove flattenedAccessors
nitely Dec 5, 2025
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1 change: 1 addition & 0 deletions .gitignore
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Original file line number Diff line number Diff line change
Expand Up @@ -10,3 +10,4 @@ tests/test_help
tests/test_argument
tests/test_parsecmdarg
tests/test_obsolete
tests/test_flatten_pragma
18 changes: 18 additions & 0 deletions README.md
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Expand Up @@ -389,6 +389,24 @@ let c = MyConf.load(onLoaded = myLogger)

-----------------

```nim
template flatten* {.pragma.}
```

Apply it to an object field to traverse the object options as if they were "top-level".
This allows the object options to be reused in various configurations.

```nim
template flatten*(v: typed) {.pragma.}
```

The default values for the object options can be overridden
with a tuple of field names and values. For example:
`opts {.flatten: (opt1: "my default").}: OptsConf` where `opt1`
is a `OptsConf` field of type string.

-----------------

```nim
template implicitlySelectable* {.pragma.}
```
Expand Down
178 changes: 156 additions & 22 deletions confutils.nim
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Expand Up @@ -14,7 +14,7 @@ import
std/[enumutils, options, strutils, wordwrap],
results,
stew/shims/macros,
confutils/[defs, cli_parser, config_file]
confutils/[defs, cli_parser, config_file, utils]

export
options, results, defs, config_file
Expand Down Expand Up @@ -809,24 +809,143 @@ template debugMacroResult(macroName: string) {.dirty.} =
echo "\n-------- ", macroName, " ----------------------"
echo result.repr

type
ConfFieldDescRef = ref ConfFieldDesc
ConfFieldDesc = object
field: FieldDescription
parent: ConfFieldDescRef

proc newConfFieldDesc(
field: FieldDescription, parent: ConfFieldDescRef
): ConfFieldDescRef =
ConfFieldDescRef(field: field, parent: parent)

proc fieldCaseBranch(cf: ConfFieldDesc): NimNode =
if cf.field.caseBranch != nil:
cf.field.caseBranch
elif cf.parent != nil:
fieldCaseBranch(cf.parent[])
else:
nil

proc fieldCaseField(cf: ConfFieldDesc): NimNode =
if cf.field.caseField != nil:
cf.field.caseField
elif cf.parent != nil:
fieldCaseField(cf.parent[])
else:
nil

proc validateFlattenOptions(field: FieldDescription, children: openArray[ConfFieldDesc]) =
## Validate flatten tuple options exist
doAssert field.readPragma"flatten" != nil
let ftn = field.readPragma"flatten"
if ftn.kind == nnkTupleConstr:
if ftn.len > 0 and ftn[0].kind != nnkExprColonExpr:
error "invalid flatten options, expected tuple of (k: v)", ftn
var found = newSeq[NimNode]()
for cf in children:
for x in ftn:
if eqIdent(x[0], cf.field.name):
found.add x[0]
for x in ftn:
if x[0] notin found:
error "invalid flatten option: " & $x[0], ftn

proc confFields(typeImpl: NimNode, parent: ConfFieldDescRef = nil): seq[ConfFieldDesc] =
result = newSeq[ConfFieldDesc]()
for field in recordFields(typeImpl):
let ftn = field.readPragma"flatten"
if ftn != nil:
let firstChildIdx = result.len
for cf in confFields(getImpl(field.typ), newConfFieldDesc(field, parent)):
result.add cf
validateFlattenOptions(field, toOpenArray(result, firstChildIdx, result.len-1))
else:
result.add ConfFieldDesc(field: field, parent: parent)

proc genFieldDotExpr(cf: ConfFieldDesc): NimNode =
if cf.parent != nil:
dotExpr(genFieldDotExpr(cf.parent[]), cf.field.name)
else:
cf.field.name

proc fullFieldName(cf: ConfFieldDesc): string =
if cf.parent != nil:
$fullFieldName(cf.parent[]) & "Dot" & $cf.field.name
else:
$cf.field.name

proc fieldCaseFieldFullName(cf: ConfFieldDesc): string =
if cf.field.caseField != nil:
if cf.parent != nil:
fullFieldName(cf.parent[]) & "Dot" & $cf.field.caseField.getFieldName
else:
$cf.field.caseField.getFieldName
else:
doAssert cf.parent != nil, "caseField not found"
fieldCaseFieldFullName(cf.parent[])

proc extractTypedValue(n: NimNode): NimNode =
case n.kind
of nnkSym:
let impl = n.getImpl
case impl.kind
of nnkConstDef: extractTypedValue(impl[2])
of nnkStrLit .. nnkTripleStrLit: impl # Nim 1.6 compat
else: n
else:
n

proc flattenDefaultValue(field: FieldDescription, parent: ConfFieldDescRef): NimNode =
if parent == nil:
return nil
let ancestorVal = flattenDefaultValue(field, parent[].parent)
if ancestorVal != nil:
return ancestorVal
let ftn = parent[].field.readPragma"flatten"
case ftn.kind
of nnkSym: nil
of nnkTupleConstr:
var ret: NimNode = nil
for x in ftn:
if eqIdent(x[0], field.name):
ret = extractTypedValue(x[1])
ret
else:
error "Bad flatten pragma", ftn
nil

proc readDefaultValueOverride(cf: ConfFieldDesc): NimNode =
flattenDefaultValue(cf.field, cf.parent)

proc readDefaultValue(cf: ConfFieldDesc): NimNode =
result = cf.readDefaultValueOverride()
if result == nil:
result = cf.field.readPragma"defaultValue"

proc generateFieldSetters(RecordType: NimNode): NimNode =
var recordDef = getImpl(RecordType)
let makeDefaultValue = bindSym"makeDefaultValue"

result = newTree(nnkStmtListExpr)
var settersArray = newTree(nnkBracket)

for field in recordFields(recordDef):
for cf in confFields(recordDef):
let field = cf.field
var
setterName = ident($field.name & "Setter")
setterName = ident(cf.fullFieldName() & "Setter")
fieldName = field.name
namePragma = field.readPragma"name"
paramName = if namePragma != nil: namePragma
else: fieldName
paramName =
if namePragma != nil:
namePragma
else:
fieldName
configVar = ident "config"
configField = newTree(nnkDotExpr, configVar, fieldName)
defaultValue = field.readPragma"defaultValue"
completerName = ident($field.name & "Complete")
configField = dotExpr(configVar, genFieldDotExpr(cf))
defaultValue = cf.readDefaultValue()
completerName = ident(cf.fullFieldName() & "Complete")
isFieldDiscriminator = newLit field.isDiscriminator

if defaultValue == nil:
Expand Down Expand Up @@ -877,6 +996,8 @@ proc generateFieldSetters(RecordType: NimNode): NimNode =
debugMacroResult "Field Setters"

func checkDuplicate(cmd: CmdInfo, opt: OptInfo, fieldName: NimNode) =
if opt.kind == Discriminator and opt.isCommand:
return
for x in cmd.opts:
if opt.name == x.name:
error "duplicate name detected: " & opt.name, fieldName
Expand Down Expand Up @@ -920,16 +1041,22 @@ proc cmdInfoFromType(T: NimNode): CmdInfo =

var
recordDef = getImpl(T)
discriminatorFields = newSeq[OptInfo]()
discriminatorFields = newSeq[(string, OptInfo)]()
fieldIdx = 0

for field in recordFields(recordDef):
for cf in confFields(recordDef):
let
field = cf.field
isImplicitlySelectable = field.readPragma"implicitlySelectable" != nil
defaultValue = field.readPragma"defaultValue"
defaultValue = cf.readDefaultValue()
defaultValueDesc = field.readPragma"defaultValueDesc"
defaultInHelp = if defaultValueDesc != nil: defaultValueDesc
else: defaultValue
defaultInHelp =
if cf.readDefaultValueOverride() != nil:
defaultValue
elif defaultValueDesc != nil:
defaultValueDesc
else:
defaultValue
defaultInHelpText = toText(defaultInHelp)
obsoleteMsg = field.readPragma"obsolete"
separator = field.readPragma"separator"
Expand Down Expand Up @@ -962,7 +1089,7 @@ proc cmdInfoFromType(T: NimNode): CmdInfo =
inc fieldIdx

if field.isDiscriminator:
discriminatorFields.add opt
discriminatorFields.add (cf.fullFieldName(), opt)
let cmdType = field.typ.getImpl[^1]
if cmdType.kind != nnkEnumTy:
error "Only enums are supported as case object discriminators", field.name
Expand All @@ -988,20 +1115,25 @@ proc cmdInfoFromType(T: NimNode): CmdInfo =
if opt.defaultSubCmd == -1:
error "The default value is not a valid enum value", defaultValue

if field.caseField != nil and field.caseBranch != nil:
let fieldName = field.caseField.getFieldName
var discriminator = findOpt(discriminatorFields, $fieldName)
let caseField = cf.fieldCaseField()
let caseBranch = cf.fieldCaseBranch()
if caseField != nil and caseBranch != nil:
let fieldName = cf.fieldCaseFieldFullName()
var discriminator: OptInfo
for (name, opt) in discriminatorFields:
if fieldName == name:
discriminator = opt

if discriminator == nil:
error "Unable to find " & $fieldName
error "Unable to find " & $caseField.getFieldName

if field.caseBranch.kind == nnkElse:
if caseBranch.kind == nnkElse:
error "Sub-command parameters cannot appear in an else branch. " &
"Please specify the sub-command branch precisely", field.caseBranch[0]
"Please specify the sub-command branch precisely", caseBranch[0]

# support multiple subcommands in the same branch; skip branch body
for enumValIdx in 0 .. field.caseBranch.len - 2:
var branchEnumVal = field.caseBranch[enumValIdx]
for enumValIdx in 0 .. caseBranch.len - 2:
var branchEnumVal = caseBranch[enumValIdx]
if branchEnumVal.kind == nnkDotExpr:
branchEnumVal = branchEnumVal[1]
let cmd = findCmd(discriminator.subCmds, $branchEnumVal)
Expand Down Expand Up @@ -1030,6 +1162,8 @@ macro configurationRtti(RecordType: type): untyped =

result = newTree(nnkPar, newLitFixed cmdInfo, fieldSetters)

debugMacroResult "configurationRtti"

when hasSerialization:
template addConfigFileImpl(
secondarySources: auto,
Expand Down
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