Re: Hooks

[Peter Stephenson <pws@xxxxxxx>]

"Nikolai Weibull" <now@xxxxxxxx> wrote:
> > This is even further away from the original subject, but I've often felt
> > that functions like preexec and chpwd are getting a bit overloaded and
> > are unnecessarily hard to maintain automatically.  It would be easy to
> > add an array which could contain names of functions to be executed,
> > similar to Emacs hooks.
> 
> Yes, please do add.

This is it; it's not a particularly big change.  I think the array names
precmd_functions etc. are obvious enough to be uncontroversial.

Index: Doc/Zsh/func.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/func.yo,v
retrieving revision 1.12
diff -u -r1.12 func.yo
--- Doc/Zsh/func.yo	20 Mar 2006 11:06:25 -0000	1.12
+++ Doc/Zsh/func.yo	7 Nov 2006 18:10:48 -0000
@@ -151,26 +151,44 @@
 example(autoload +X myfunc)
 
 sect(Special Functions)
-The following functions, if defined, have special meaning to
-the shell:
+Certain functions, if defined, have special meaning to the shell.
+
+In the case of tt(chpwd), tt(periodic), tt(precmd) and tt(preexec) it is
+possible to define an array that has the same name with `tt(_functions)'
+appended.  Any element in such an array is taken as the name of a function
+to execute; it is executed in the same context and with the same arguments
+as the basic function.  For example, if tt($chpwd_functions) is an array
+containing the values `tt(mychpwd)', `tt(chpwd_save_dirstack)', then the
+shell attempts to execute the functions `tt(chpwd)', `tt(mychpwd)' and
+`tt(chpwd_save_dirstack)', in that order.  Any function that does not exist
+is silently ignored.  A function found by this mechanism is referred to
+elsewhere as a `hook function'.
 
 startitem()
 findex(chpwd)
+vindex(chpwd_functions)
 item(tt(chpwd))(
 Executed whenever the current working directory is changed.
 )
 findex(periodic)
+vindex(periodic_functions)
 item(tt(periodic))(
 vindex(PERIOD)
 If the parameter tt(PERIOD)
 is set, this function is executed every tt($PERIOD)
-seconds, just before a prompt.
+seconds, just before a prompt.  Note that if multiple functions
+are defined using the array tt(periodic_functions) only one
+period is applied to the complete set of functions, and the
+scheduled time is not reset if the list of functions is altered.
+Hence the set of functions is always called together.
 )
 findex(precmd)
+vindex(precmd_functions)
 item(tt(precmd))(
 Executed before each prompt.
 )
 findex(preexec)
+vindex(preexec_functions)
 item(tt(preexec))(
 Executed just after a command has been read and is about to be
 executed.  If the history mechanism is active (and the line was not
Index: Doc/Zsh/options.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/options.yo,v
retrieving revision 1.49
diff -u -r1.49 options.yo
--- Doc/Zsh/options.yo	1 Nov 2006 12:25:22 -0000	1.49
+++ Doc/Zsh/options.yo	7 Nov 2006 18:10:49 -0000
@@ -912,8 +912,11 @@
 
 The check is omitted if the commands run from the previous command line
 included a `tt(jobs)' command, since it is assumed the user is aware that
-there are background or suspended jobs.  A `tt(jobs)' command run from the
-tt(precmd) function is not counted for this purpose.
+there are background or suspended jobs.  A `tt(jobs)' command run from one
+of the hook functions defined in
+ifnzman(the section Special Functions in noderef(Functions))\
+ifzman(the section SPECIAL FUNCTIONS in zmanref(zshmisc))
+is not counted for this purpose.
 )
 pindex(HUP)
 cindex(jobs, HUP)
Index: Src/builtin.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/builtin.c,v
retrieving revision 1.165
diff -u -r1.165 builtin.c
--- Src/builtin.c	5 Nov 2006 21:49:18 -0000	1.165
+++ Src/builtin.c	7 Nov 2006 18:10:50 -0000
@@ -1087,7 +1087,6 @@
 static void
 cd_new_pwd(int func, LinkNode dir)
 {
-    Eprog prog;
     char *new_pwd, *s;
     int dirstacksize;
 
@@ -1134,15 +1133,9 @@
     }
 
     /* execute the chpwd function */
-    if ((prog = getshfunc("chpwd")) != &dummy_eprog) {
-	int osc = sfcontext;
-
-	fflush(stdout);
-	fflush(stderr);
-	sfcontext = SFC_HOOK;
-	doshfunc("chpwd", prog, NULL, 0, 1);
-	sfcontext = osc;
-    }
+    fflush(stdout);
+    fflush(stderr);
+    callhookfunc("chpwd", NULL, 1);
 
     dirstacksize = getiparam("DIRSTACKSIZE");
     /* handle directory stack sizes out of range */
Index: Src/init.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/init.c,v
retrieving revision 1.70
diff -u -r1.70 init.c
--- Src/init.c	29 Sep 2006 20:43:33 -0000	1.70
+++ Src/init.c	7 Nov 2006 18:10:50 -0000
@@ -137,11 +137,9 @@
 	}
 	if (hend(prog)) {
 	    int toksav = tok;
-	    Eprog preprog;
 
-	    if (toplevel && (preprog = getshfunc("preexec")) != &dummy_eprog) {
+	    if (toplevel && getshfunc("preexec") != &dummy_eprog) {
 		LinkList args;
-		int osc = sfcontext;
 		char *cmdstr;
 
 		args = znewlinklist();
@@ -155,10 +153,14 @@
 		zaddlinknode(args, getjobtext(prog, NULL));
 		zaddlinknode(args, cmdstr = getpermtext(prog, NULL));
 
-		sfcontext = SFC_HOOK;
-		doshfunc("preexec", preprog, args, 0, 1);
-		sfcontext = osc;
+		callhookfunc("preexec", args, 1);
+
 		zsfree(cmdstr);
+		/*
+		 * The following frees the nodes in the list, but
+		 * doesn't free the data: the only data that
+		 * needs freeing is cmdstr, just handled.
+		 */
 		freelinklist(args, (FreeFunc) NULL);
 		errflag = 0;
 	    }
Index: Src/utils.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/utils.c,v
retrieving revision 1.144
diff -u -r1.144 utils.c
--- Src/utils.c	19 Oct 2006 08:50:00 -0000	1.144
+++ Src/utils.c	7 Nov 2006 18:10:51 -0000
@@ -1079,28 +1079,53 @@
 /**/
 time_t lastwatch;
 
+/*
+ * Call a function given by "name" with optional arguments
+ * "lnklist".  If "arrayp" is not zero, we also look through
+ * the array "name"_functions and execute functions found there.
+ */
+
 /**/
 mod_export int
-callhookfunc(char *name, LinkList lnklst)
+callhookfunc(char *name, LinkList lnklst, int arrayp)
 {
     Eprog prog;
-
-    if ((prog = getshfunc(name)) != &dummy_eprog) {
 	/*
 	 * Save stopmsg, since user doesn't get a chance to respond
 	 * to a list of jobs generated in a hook.
 	 */
-	int osc = sfcontext, osm = stopmsg;
+    int osc = sfcontext, osm = stopmsg, stat = 1;
+
+    sfcontext = SFC_HOOK;
 
-	sfcontext = SFC_HOOK;
+    if ((prog = getshfunc(name)) != &dummy_eprog) {
 	doshfunc(name, prog, lnklst, 0, 1);
-	sfcontext = osc;
-	stopmsg = osm;
+	stat = 0;
+    }
 
-	return 0;
+    if (arrayp) {
+	char **arrptr;
+	int namlen = strlen(name);
+#define HOOK_SUFFIX	"_functions"
+#define HOOK_SUFFIX_LEN	11	/* including NUL byte */
+	VARARR(char, arrnam, namlen + HOOK_SUFFIX_LEN);
+	memcpy(arrnam, name, namlen);
+	memcpy(arrnam + namlen, HOOK_SUFFIX, HOOK_SUFFIX_LEN);
+
+	if ((arrptr = getaparam(arrnam))) {
+	    for (; *arrptr; arrptr++) {
+		if ((prog = getshfunc(*arrptr)) != &dummy_eprog) {
+		    doshfunc(arrnam, prog, lnklst, 0, 1);
+		    stat = 0;
+		}
+	    }
+	}
     }
 
-    return 1;
+    sfcontext = osc;
+    stopmsg = osm;
+
+    return stat;
 }
 
 /* do pre-prompt stuff */
@@ -1136,15 +1161,15 @@
 
     /* If a shell function named "precmd" exists, *
      * then execute it.                           */
-    callhookfunc("precmd", NULL);
+    callhookfunc("precmd", NULL, 1);
     if (errflag)
 	return;
 
-    /* If 1) the parameter PERIOD exists, 2) the shell function     *
+    /* If 1) the parameter PERIOD exists, 2) a hook function for    *
      * "periodic" exists, 3) it's been greater than PERIOD since we *
-     * executed "periodic", then execute it now.                    */
+     * executed any such hook, then execute it now.                 */
     if (period && (time(NULL) > lastperiodic + period) &&
-	!callhookfunc("periodic", NULL))
+	!callhookfunc("periodic", NULL, 1))
 	lastperiodic = time(NULL);
     if (errflag)
 	return;
Index: Src/Zle/zle_main.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/Zle/zle_main.c,v
retrieving revision 1.93
diff -u -r1.93 zle_main.c
--- Src/Zle/zle_main.c	30 Oct 2006 14:13:39 -0000	1.93
+++ Src/Zle/zle_main.c	7 Nov 2006 18:10:51 -0000
@@ -716,7 +716,7 @@
 # endif
 
 
-			callhookfunc(lwatch_funcs[i], funcargs);
+			callhookfunc(lwatch_funcs[i], funcargs, 0);
 			if (errflag) {
 			    /* No sensible way of handling errors here */
 			    errflag = 0;
Index: Test/A05execution.ztst
===================================================================
RCS file: /cvsroot/zsh/zsh/Test/A05execution.ztst,v
retrieving revision 1.4
diff -u -r1.4 A05execution.ztst
--- Test/A05execution.ztst	29 Jul 2004 15:10:24 -0000	1.4
+++ Test/A05execution.ztst	7 Nov 2006 18:10:51 -0000
@@ -105,6 +105,18 @@
 0q:chpwd
 >Changed to $ZTST_testdir/command.tmp
 
+  chpwd() { print chpwd: changed to $PWD; }
+  chpwdfn1()  { print chpwdfn1: changed to $PWD; }
+  chpwdfn2()  { print chpwdfn2: changed to $PWD; }
+  chpwd_functions=(chpwdfn1 '' chpwdnonexistentfn chpwdfn2)
+  cd .
+  unfunction chpwd
+  unset chpwd_functions
+0q:chpwd_functions
+>chpwd: changed to $ZTST_testdir/command.tmp
+>chpwdfn1: changed to $ZTST_testdir/command.tmp
+>chpwdfn2: changed to $ZTST_testdir/command.tmp
+
 # Hard to test periodic, precmd and preexec non-interactively.
 
   fn() { TRAPEXIT() { print Exit; }; }


-- 
Peter Stephenson <pws@xxxxxxx>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070


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