Update documentation.

darcs-hash:32d8156e02effa3d43909670add8ac0701acba62

1 files changed, 107 insertions, 0 deletions

diff --git a/Lisp/init.lisp b/Lisp/init.lisp
index 94c87a1..a290a8d 100644
--- a/Lisp/init.lisp
+++ b/Lisp/init.lisp
@@ -35,3 +35,110 @@
              ((:gnu) 'objcl-features:gnu-runtime)
              ((:next) 'objcl-features:next-runtime))
            *features*))
+
+
+(setf (documentation '+nil+ 'variable)
+      "The Objective-C constant value `nil`.
+
+## Value Type:
+
+an **object** of type __id__.
+
+
+## Description:
+
+__+nil+__ is the constant corresponding to the Objective-C `nil` value.
+
+__+nil+__ is not a value that any method invocation should return.
+Whenever `nil` is returned by an Objective-C invocation, It is the job
+of Objective-CL to convert it to __nil__.  Similarly, __null__ arguments
+are converted to `nil` automatically.  Still, there may be occasions in
+which it is useful to have `nil` as an __id__ instance.  Therefore, it
+is provided here.
+
+Note that, in the general case, `nil` is not necessarily equal to
+`NULL`.")
+
+
+(setf (documentation '+yes+ 'variable)
+      "The Objective-C boolean value `YES`.
+
+## Value Type:
+
+a **number**.
+
+
+## Description:
+
+__+yes+__ is the constant corresponding to the Objective-C `YES` value.
+
+As there is no way to distinguish methods that return booleans from
+those that return numbers in the Objective-C runtime, all invocations
+that ought to return booleans will actually return one of two
+compile-time Objective-C constants: either `YES` or `NO`.  Lisp code
+using Objective-CL needs to be aware of this and test return values
+accordingly.  For this to be possible, two **constant**s are defined on
+the Lisp side, analogously to Objective-C.  These are called __+yes+__
+and __+no+__.
+
+
+## Examples:
+
+    (invoke (find-class 'ns-string)
+            :is-subclass-of-class (find-class 'ns-object))
+     ;=> #.YES
+
+    (invoke (find-class 'ns-object)
+            :is-subclass-of-class (find-class 'ns-object))
+     ;=> #.YES
+
+    (invoke (find-class 'ns-object)
+            :is-subclass-of-class (find-class 'ns-string))
+     ;=> #.NO
+
+
+## See Also:
+
+  __+no+__")
+
+
+(setf (documentation '+no+ 'variable)
+      "The Objective-C boolean value `NO`.
+
+## Value Type:
+
+a **number**.
+
+
+## Description:
+
+__+no+__ is the constant corresponding to the Objective-C `NO` value.
+
+As there is no way to distinguish methods that return booleans from
+those that return numbers in the Objective-C runtime, all invocations
+that ought to return booleans will actually return one of two
+compile-time Objective-C constants: either `YES` or `NO`.  Lisp code
+using Objective-CL needs to be aware of this and test return values
+accordingly.  For this to be possible, two **constant**s are defined on
+the Lisp side, analogously to Objective-C.  These are called __+yes+__
+and __+no+__.
+
+
+## Examples:
+
+    (invoke (find-class 'ns-string)
+            :is-subclass-of-class (find-class 'ns-object))
+     ;=> #.YES
+
+    (invoke (find-class 'ns-object)
+            :is-subclass-of-class (find-class 'ns-object))
+     ;=> #.YES
+
+    (invoke (find-class 'ns-object)
+            :is-subclass-of-class (find-class 'ns-string))
+     ;=> #.NO
+
+
+## See Also:
+
+  __+yes+__")
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