unknownStable? (object -- isUnknownStable)

Inputs

• object: Current stack object whose unknown-stability is tested.

Outputs

• isUnknownStable: Known Cond result of the current unknownness-and-stability test described below.

unknownStable? tests whether an In-place object is currently stable and has an unknown value. For a non-Meta Struct, every solid field must meet that condition. The predicate does not itself forget values or change stability.

This predicate follows the referenced target for known non-NIL Ref objects. It is the same predicate as isDynamic. Fully known In-place objects therefore report FALSE. Text, Code, and Meta objects also report FALSE, including callable non-NIL Code objects.

Behavior

• An In-place object with unknown contents reports TRUE only while it is stable; an unstable object reports FALSE.
• A known non-NIL Ref object reports the unknownStable? result of its target.
• Known NIL Ref objects and unknown Ref objects report FALSE.

Example

{} 0 {} [
  value: 7;
  codeLocal: {} () {} codeRef;
  unknownValue: 0 dynamic;
  unknownText: 0 ("") dynamic @; # an unknown Text
  [] !codeLocal # a non-NIL Code

  "-- stable? versus unknownStable? for In-place values --" printCompilerMessage
  7 stable? printStack _:;
  7 unknownStable? printStack _:;
  7 isDynamic printStack _:;
  unknownValue stable? printStack _:;
  unknownValue unknownStable? printStack _:;
  unknownValue isDynamic printStack _:;

  "-- stable? versus unknownStable? for references --" printCompilerMessage
  @value stable? printStack _:;
  @value unknownStable? printStack _:;
  @value isDynamic printStack _:;
  @value dynamic stable? printStack _:;
  @value dynamic unknownStable? printStack _:;
  @value dynamic isDynamic printStack _:;
  0nx value addressToReference stable? printStack _:; # a NIL Ref
  0nx value addressToReference unknownStable? printStack _:;
  0nx value addressToReference isDynamic printStack _:;

  "-- stable? versus unknownStable? for text, code, meta --" printCompilerMessage
  "hi" stable? printStack _:;
  "hi" unknownStable? printStack _:;
  "hi" isDynamic printStack _:;
  unknownText stable? printStack _:;
  unknownText unknownStable? printStack _:;
  unknownText isDynamic printStack _:;
  {} () {} codeRef stable? printStack _:;
  {} () {} codeRef unknownStable? printStack _:;
  {} () {} codeRef isDynamic printStack _:;
  @codeLocal stable? printStack _:;
  @codeLocal unknownStable? printStack _:;
  @codeLocal isDynamic printStack _:;
  () stable? printStack _:;
  () unknownStable? printStack _:;
  () isDynamic printStack _:;

  0
] "main" exportFunction

Expected Output During Compilation

-- stable? versus unknownStable? for In-place values --
TRUE
FALSE
FALSE
TRUE
TRUE
TRUE
-- stable? versus unknownStable? for references --
TRUE
FALSE
FALSE
TRUE
TRUE
TRUE
FALSE
FALSE
FALSE
-- stable? versus unknownStable? for text, code, meta --
TRUE
FALSE
FALSE
FALSE
FALSE
FALSE
FALSE
FALSE
FALSE
FALSE
FALSE
FALSE
TRUE
FALSE
FALSE

See also

• isDirty builtin (object -- isDirty) Current stack-object instability predicate; exact opposite of stable?.
• dynamic builtin (object -- dynamicValue) Current stack-object forgotten-contents conversion.
• isDynamic builtin (object -- isDynamic) Same current stable-and-unknown predicate under a different builtin name.
• isStatic builtin (object -- isKnown) Historical name of the same current stack-object knownness predicate.
• known? builtin (object -- isKnown) Preferred public name of the same current stack-object knownness predicate.
• stable? builtin (object -- isStable) Current stack-object stability predicate; exact opposite of isDirty.