ncurses 6.0 - patch 20171125

[ncurses.git] / man / curs_touch.3x

diff --git a/man/curs_touch.3x b/man/curs_touch.3x
index d576fe5d74f15321d395f38445e1d5ca7dc4d110..8d4a88cb0cfb7c1b4c7ae3867dedd98ea24dd0af 100644 (file)
--- a/man/curs_touch.3x
+++ b/man/curs_touch.3x
@@ -26,7 +26,7 @@
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"
-.\" $Id: curs_touch.3x,v 1.17 2017/11/18 23:40:19 tom Exp $
+.\" $Id: curs_touch.3x,v 1.20 2017/11/25 16:19:42 tom Exp $
 .TH curs_touch 3X ""
 .na
 .hy 0
@@ -90,7 +90,16 @@ In this implementation
 returns an error 
 if the window pointer is null, or
 if the line number is outside the window.
-Note that ERR is distinct from \fBTRUE\fP and \fBFALSE\fP, which are the normal return values of this function.
+.IP
+The constant \fBERR\fP is distinct from \fBTRUE\fP and \fBFALSE\fP,
+which are the normal return values of this function.
+Because the function returns a \fBbool\fP,
+returning \fBERR\fP (which is neither \fBTRUE\fP nor \fBFALSE\fP)
+may not be supported by the compiler.
+.IP
+To provide error-checking and also match the X/Open function prototype,
+the \fBERR\fP is provided by a macro named \fBis_linetouched\fP.
+The actual function returns \fBFALSE\fP when it detects an error.
 .TP 5
 \fBwtouchln\fP
 returns an error 
@@ -98,14 +107,19 @@ if the window pointer is null, or
 if the line number is outside the window.
 .RE
 .SH PORTABILITY
-The XSI Curses standard, Issue 4 describes these functions.
 .PP
-Some historic curses implementations had, as an undocumented feature, the
-ability to do the equivalent of \fBclearok(..., 1)\fR by saying
-\fBtouchwin(stdscr)\fR or \fBclear(stdscr)\fR.  This will not work under
-ncurses.
+These functions were introduced by SVr4.
+The Solaris curses header file,
+for instance, defines both an actual function and macro for each.
+The macros give the same result as the actual functions.
+SVr4 curses does not check the window parameter \fIwin\fP to ensure
+that it is not \fBNULL\fP;
+otherwise this implementation behaves the same as SVr4.
+.PP
+The XSI Curses standard, Issue 4 describes these functions,
+but defines no error conditions.
 .SH NOTES
-Note that all routines except \fBwtouchln\fR may be macros.
+All of these routines except \fBwtouchln\fR may be macros.
 .SH SEE ALSO
 \fBcurses\fR(3X),
 \fBcurs_refresh\fR(3X),