path: root/doc
diff options
authorJemma Issroff <>2021-12-09 11:23:51 -0500
committerGitHub <>2021-12-09 11:23:51 -0500
commitb859397e1b25a3f7847a380e7dd7db62f94fbe66 (patch)
tree93d149b871ccfb19e604080ccf4ce4c07635b4cd /doc
parentbcc2bb28b04054106f4a36e8fd69b2af6ecb033a (diff)
[DOC] Stop recommending Qfalse==0 assumption to C extensions
Encourage use of RTEST(), direct Qfalse comparison, and remove references to Qfalse == 0 in extension documentation. See [Bug #18397] for detail. [ci skip]
Notes: Merged: Merged-By: XrXr
Diffstat (limited to 'doc')
1 files changed, 3 insertions, 1 deletions
diff --git a/doc/extension.rdoc b/doc/extension.rdoc
index 1054e6a6af..15417179e1 100644
--- a/doc/extension.rdoc
+++ b/doc/extension.rdoc
@@ -93,7 +93,9 @@ There are also faster check macros for fixnums and nil.
The data for type T_NIL, T_FALSE, T_TRUE are nil, false, true
respectively. They are singletons for the data type.
The equivalent C constants are: Qnil, Qfalse, Qtrue.
-Note that Qfalse is false in C also (i.e. 0), but not Qnil.
+RTEST() will return true if a VALUE is neither Qfalse nor Qnil.
+If you need to differentiate Qfalse from Qnil,
+specifically test against Qfalse.
The T_FIXNUM data is a 31bit or 63bit length fixed integer.
This size depends on the size of long: if long is 32bit then