Address back-handed requested missing feature to have "secret" option…

…s via

    nim-lang/Nim#12425
Usage is the CL author saying `help={"param": "SUPPRESS"}` with the special
string being re-definable via, e.g., `clCfg.hTabSuppress = "**HIDDEN**"`.
Ammend test prog to try it out & update reference output for line numbers.

cligen.nim

@@ -24,6 +24,7 @@ type    # Main defns CLI authors need be aware of (besides top-level API calls)
     reqSep*:      bool           ## ``parseopt3.initOptParser`` parameter
     sepChars*:    set[char]      ## ``parseopt3.initOptParser`` parameter
     opChars*:     set[char]      ## ``parseopt3.initOptParser`` parameter
+    hTabSuppress*: string        ## Magic val for per-param help to suppress
 
   HelpOnly*    = object of Exception
   VersionOnly* = object of Exception
@@ -40,7 +41,8 @@ var clCfg* = ClCfg(
   reqSep:      false,
   sepChars:    { '=', ':' },
   opChars:     { '+', '-', '*', '/', '%', '@', ',', '.', '&',
-                 '|', '~', '^', '$', '#', '<', '>', '?' })
+                 '|', '~', '^', '$', '#', '<', '>', '?' },
+  hTabSuppress: "SUPPRESS")
 {.pop.}
 
 proc toInts*(x: seq[ClHelpCol]): seq[int] =
@@ -405,7 +407,8 @@ macro dispatchGen*(pro: typed{nkSym}, cmdName: string="", doc: string="",
          `apId`.parNm = `parNm`; `apId`.parSh = `sh`; `apId`.parReq = `isReq`
          `apId`.parRend = if `hky`.len>0: `hky` else:helpCase(`parNm`,clLongOpt)
          let descr = getDescription(`defVal`, `parNm`, `hlp`)
-         `tabId`.add(argHelp(`defVal`, `apId`) & descr)
+         if descr != `cf`.hTabSuppress:
+           `tabId`.add(argHelp(`defVal`, `apId`) & descr)
          if `apId`.parReq != 0: `tabId`[^1][2] = `apId`.val4req
          `cbId`.incl(optionNormalize(`parNm`), `apId`.parRend)
          `allId`.add(helpCase(`parNm`, clLongOpt)))

test/PerParam.nim

@@ -1,14 +1,16 @@
-proc demo(al_pha=1, be_ta=2.0, verb=false, item="", args: seq[string]) =
+proc demo(al_pha=1, be_ta=2.0, verb=false, jk=9, item="", args: seq[string]) =
   ## demo entry point with varied, meaningless parameters.  A Nim invocation
   ## might be: demo(alpha=2, @[ "hi", "ho" ]) corresponding to the command
   ## invocation "demo --alpha=2 hi ho" (assuming executable gets named demo).
   echo "alpha:", alpha, " beta:", beta, " verb:", verb, " item:", repr(item)
+  echo "jk: ", jk
   for i, arg in args: echo "positional[", i, "]: ", repr(arg)
 
 when isMainModule:
   import cligen
   dispatch(demo,
            help = { "al-pha" : "growth constant",
-                    "be-ta"  : "shrink target" },
+                    "be-ta"  : "shrink target",
+                    "jk"     : "SUPPRESS" },
            short = { "a-lpha" : 'z',
                      "b-eta" : '\0' })

test/ref

@@ -747,9 +747,9 @@ Options(opt-arg sep :|=|spc):
 
 ==> test/TwoNondefaultedSeq.out <==
 test/TwoNondefaultedSeq.nim(9, 11) template/generic instantiation of `dispatch` from here
-cligen.nim(688, 14) template/generic instantiation of `dispatchCf` from here
-cligen.nim(674, 14) template/generic instantiation of `dispatchGen` from here
-cligen.nim(186, 16) Warning: cligen only supports one seq param for positional args; using `args`, not `stuff`.  Use `positional` parameter to `dispatch` to override this. [User]
+cligen.nim(691, 14) template/generic instantiation of `dispatchCf` from here
+cligen.nim(677, 14) template/generic instantiation of `dispatchGen` from here
+cligen.nim(188, 16) Warning: cligen only supports one seq param for positional args; using `args`, not `stuff`.  Use `positional` parameter to `dispatch` to override this. [User]
 Usage:
   demo [required&optional-params] [args: string...]
 demo entry point with varied, meaningless parameters.