Re: [PATCH] Generalize start-process with keyword args

[Daiki Ueno <ueno@gnu.org>]

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Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> (Fstart_process): Define as a wrapper around Fmake_process.
>
> Could we move this to Elisp?

Thanks for the comment.  I forgot that the initial patch did that.
Fixed in the attached patch.

>> +Omitting a keyword is always equivalent to specifying it with value
>> +@code{nil}, except for @code{:coding} and @code{:connection-type}.
>
> Could we eliminate those two exceptions?

I think `:coding' at least needs to be treated specially, because if it
is omitted, other methods to determine the coding system take place
(`coding-system-for-{read,write}' and `find-operation-coding-system').
This is the same behavior as `make-network-process and
`make-serial-process' and maybe it is not worth breaking the
consistency.

`:connection-type' is there because the default value of the counterpart
global variable `process-connection-type' is t (not nil).  So, yes, it
could be eliminated if it is given another name which means a negation,
say `:nopty'.  But I'm not sure if it is intuitive for users.

Regards,
-- 
Daiki Ueno

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From 76fd9ac3d6fa8d95b2cc63da3cec226533962285 Mon Sep 17 00:00:00 2001
From: Daiki Ueno <ueno@gnu.org>
Date: Mon, 16 Mar 2015 11:38:05 +0900
Subject: [PATCH] Generalize start-process with keyword args

* src/process.c (Fmake_process): New function.
(create_process, create_pty): Check p->pty_flag instead of
Vprocess_connection_type.
(syms_of_process): Register QCcommand, QCconnection_type,
and Smake_process.

* lisp/subr.el (start-process): New function, ported from the C
implementation.

* doc/lispref/processes.texi (Asynchronous Processes): Mention
`make-process'.
---
 doc/lispref/ChangeLog      |   4 ++
 doc/lispref/processes.texi |  55 +++++++++++++++
 lisp/ChangeLog             |   5 ++
 lisp/subr.el               |  22 ++++++
 src/ChangeLog              |   8 +++
 src/process.c              | 170 +++++++++++++++++++++++++++++++++------------
 6 files changed, 219 insertions(+), 45 deletions(-)

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 260656c..06d4630 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,7 @@
+2015-03-16  Daiki Ueno  <ueno@gnu.org>
+
+	* processes.texi (Asynchronous Processes): Mention `make-process'.
+
 2015-03-09  Nicolas Petton <nicolas@petton.fr>
 
 	* sequences.texi (seq-into): Add documentation for the new
diff --git a/doc/lispref/processes.texi b/doc/lispref/processes.texi
index 177cd68..42c658d 100644
--- a/doc/lispref/processes.texi
+++ b/doc/lispref/processes.texi
@@ -692,6 +692,61 @@ use the function @code{process-tty-name} (@pxref{Process
 Information}).
 @end defvar
 
+@defun make-process &rest args
+This function is like @code{start-process}, but takes keyword arguments.
+
+The arguments @var{args} are a list of keyword/argument pairs.
+Omitting a keyword is always equivalent to specifying it with value
+@code{nil}, except for @code{:coding} and @code{:connection-type}.
+Here are the meaningful keywords:
+
+@table @asis
+@item :name @var{name}
+Use the string @var{name} as the process name.  It is modified if
+necessary to make it unique.
+
+@item :buffer @var{buffer}
+Use @var{buffer} as the process buffer.
+
+@item :command @var{command}
+Use @var{command} as the command line of the process.  @var{command}
+is a list starting with the program name, followed by strings to give
+to program as arguments.
+
+@item :coding @var{coding}
+Use @var{coding} as the coding system for this process.  To specify
+different coding systems for decoding data from the connection and for
+encoding data sent to it, specify @code{(@var{decoding} .
+@var{encoding})} for @var{coding}.
+
+If you don't specify this keyword at all, the default
+is to determine the coding systems from the data.
+
+@item :connection-type @var{TYPE}
+Initialize the type of device used to communicate with the subprocess.
+
+If you don't specify this keyword at all, the default is the value of
+the @code{process-connection-type} variable.
+
+@item :stop @var{stopped}
+If @var{stopped} is non-@code{nil}, start the network connection or
+server in the ``stopped'' state.
+
+@item :noquery @var{query-flag}
+Initialize the process query flag to @var{query-flag}.
+@xref{Query Before Exit}.
+
+@item :filter @var{filter}
+Initialize the process filter to @var{filter}.
+
+@item :sentinel @var{sentinel}
+Initialize the process sentinel to @var{sentinel}.
+@end table
+
+The original argument list, modified with the actual connection
+information, is available via the @code{process-contact} function.
+@end defun
+
 @node Deleting Processes
 @section Deleting Processes
 @cindex deleting processes
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 747a1d6..835712c 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2015-03-17  Daiki Ueno  <ueno@gnu.org>
+
+	* subr.el (start-process): New function, ported from the C
+	implementation.
+
 2015-03-15  Michael Albinus  <michael.albinus@gmx.de>
 
 	* net/tramp-adb.el:
diff --git a/lisp/subr.el b/lisp/subr.el
index deadca6..5d763f9 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -1901,6 +1901,28 @@ and the file name is displayed in the echo area."
 \f
 ;;;; Process stuff.
 
+(defun start-process (name buffer program &rest program-args)
+  "Start a program in a subprocess.  Return the process object for it.
+NAME is name for process.  It is modified if necessary to make it unique.
+BUFFER is the buffer (or buffer name) to associate with the process.
+
+Process output (both standard output and standard error streams) goes
+at end of BUFFER, unless you specify an output stream or filter
+function to handle the output.  BUFFER may also be nil, meaning that
+this process is not associated with any buffer.
+
+PROGRAM is the program file name.  It is searched for in `exec-path'
+\(which see).  If nil, just associate a pty with the buffer.  Remaining
+arguments are strings to give program as arguments.
+
+If you want to separate standard output from standard error, invoke
+the command through a shell and redirect one of them using the shell
+syntax."
+  (unless (fboundp 'make-process)
+    (error "Emacs was compiled without subprocess support"))
+  (make-process :name name :buffer buffer
+		:command (cons program program-args)))
+
 (defun process-lines (program &rest args)
   "Execute PROGRAM with ARGS, returning its output as a list of lines.
 Signal an error if the program returns with a non-zero exit status."
diff --git a/src/ChangeLog b/src/ChangeLog
index e328afc..2ec576a 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,11 @@
+2015-03-16  Daiki Ueno  <ueno@gnu.org>
+
+	* process.c (Fmake_process): New function.
+	(create_process, create_pty): Check p->pty_flag instead of
+	Vprocess_connection_type.
+	(syms_of_process): Register QCcommand, QCconnection_type, and
+	Smake_process.  Unregister Sstart_process.
+
 2015-03-15  Eli Zaretskii  <eliz@gnu.org>
 
 	* xdisp.c (handle_invisible_prop): Fix up it->position even when
diff --git a/src/process.c b/src/process.c
index 1d935ba..49f5d5c 100644
--- a/src/process.c
+++ b/src/process.c
@@ -1355,34 +1355,65 @@ DEFUN ("process-list", Fprocess_list, Sprocess_list, 0, 0, 0,
 
 static void start_process_unwind (Lisp_Object proc);
 
-DEFUN ("start-process", Fstart_process, Sstart_process, 3, MANY, 0,
+DEFUN ("make-process", Fmake_process, Smake_process, 0, MANY, 0,
        doc: /* Start a program in a subprocess.  Return the process object for it.
-NAME is name for process.  It is modified if necessary to make it unique.
-BUFFER is the buffer (or buffer name) to associate with the process.
 
-Process output (both standard output and standard error streams) goes
-at end of BUFFER, unless you specify an output stream or filter
-function to handle the output.  BUFFER may also be nil, meaning that
-this process is not associated with any buffer.
+This is similar to `start-process', but arguments are specified as
+keyword/argument pairs.  The following arguments are defined:
 
-PROGRAM is the program file name.  It is searched for in `exec-path'
-(which see).  If nil, just associate a pty with the buffer.  Remaining
-arguments are strings to give program as arguments.
+:name NAME -- NAME is name for process.  It is modified if necessary
+to make it unique.
 
-If you want to separate standard output from standard error, invoke
-the command through a shell and redirect one of them using the shell
-syntax.
+:buffer BUFFER -- BUFFER is the buffer (or buffer-name) to associate
+with the process.  Process output goes at end of that buffer, unless
+you specify an output stream or filter function to handle the output.
+BUFFER may be also nil, meaning that this process is not associated
+with any buffer.
 
-usage: (start-process NAME BUFFER PROGRAM &rest PROGRAM-ARGS)  */)
+:command COMMAND -- COMMAND is a list starting with the program file
+name, followed by strings to give to the program as arguments.
+
+:coding CODING -- If CODING is a symbol, it specifies the coding
+system used for both reading and writing for this process.  If CODING
+is a cons (DECODING . ENCODING), DECODING is used for reading, and
+ENCODING is used for writing.
+
+:noquery BOOL -- When exiting Emacs, query the user if BOOL is nil and
+the process is running.  If BOOL is not given, query before exiting.
+
+:stop BOOL -- Start process in the `stopped' state if BOOL non-nil.
+In the stopped state, a server process does not accept new
+connections, and a client process does not handle incoming traffic.
+The stopped state is cleared by `continue-process' and set by
+`stop-process'.
+
+:connection-type TYPE -- TYPE is control type of device used to
+communicate with subprocesses.  Values are nil to use a pipe, or t or
+`pty' to use a pty.
+
+:filter FILTER -- Install FILTER as the process filter.
+
+:sentinel SENTINEL -- Install SENTINEL as the process sentinel.
+
+usage: (make-process &rest ARGS)  */)
   (ptrdiff_t nargs, Lisp_Object *args)
 {
-  Lisp_Object buffer, name, program, proc, current_dir, tem;
+  Lisp_Object buffer, name, command, program, proc, contact, current_dir, tem;
   unsigned char **new_argv;
+  ptrdiff_t new_argc;
   ptrdiff_t i;
   ptrdiff_t count = SPECPDL_INDEX ();
+  struct gcpro gcpro1;
   USE_SAFE_ALLOCA;
 
-  buffer = args[1];
+  if (nargs == 0)
+    return Qnil;
+
+  /* Save arguments for process-contact and clone-process.  */
+  contact = Flist (nargs, args);
+  GCPRO1 (contact);
+
+  buffer = Fplist_get (contact, QCbuffer);
   if (!NILP (buffer))
     buffer = Fget_buffer_create (buffer);
 
@@ -1402,10 +1433,11 @@ usage: (start-process NAME BUFFER PROGRAM &rest PROGRAM-ARGS)  */)
     UNGCPRO;
   }
 
-  name = args[0];
+  name = Fplist_get (contact, QCname);
   CHECK_STRING (name);
 
-  program = args[2];
+  command = Fplist_get (contact, QCcommand);
+  program = XCAR (command);
 
   if (!NILP (program))
     CHECK_STRING (program);
@@ -1423,7 +1455,18 @@ usage: (start-process NAME BUFFER PROGRAM &rest PROGRAM-ARGS)  */)
   pset_buffer (XPROCESS (proc), buffer);
   pset_sentinel (XPROCESS (proc), Qinternal_default_process_sentinel);
   pset_filter (XPROCESS (proc), Qinternal_default_process_filter);
-  pset_command (XPROCESS (proc), Flist (nargs - 2, args + 2));
+  pset_command (XPROCESS (proc), Fcopy_sequence (command));
+
+  if (tem = Fplist_get (contact, QCnoquery), !NILP (tem))
+    XPROCESS (proc)->kill_without_query = 1;
+  if (tem = Fplist_get (contact, QCstop), !NILP (tem))
+    pset_command (XPROCESS (proc), Qt);
+
+  tem = Fplist_member (contact, QCconnection_type);
+  if (!NILP (tem))
+    XPROCESS (proc)->pty_flag = !NILP (XCAR (XCDR (tem)));
+  else
+    XPROCESS (proc)->pty_flag = !NILP (Vprocess_connection_type);
 
 #ifdef HAVE_GNUTLS
   /* AKA GNUTLS_INITSTAGE(proc).  */
@@ -1453,15 +1496,33 @@ usage: (start-process NAME BUFFER PROGRAM &rest PROGRAM-ARGS)  */)
     Lisp_Object val, *args2;
     struct gcpro gcpro1, gcpro2;
 
-    val = Vcoding_system_for_read;
+    tem = Fplist_member (contact, QCcoding);
+    if (!NILP (tem) && (!CONSP (tem) || !CONSP (XCDR (tem))))
+      tem = Qnil;
+
+    val = Qnil;
+    if (!NILP (tem))
+      {
+	val = XCAR (XCDR (tem));
+	if (CONSP (val))
+	  val = XCAR (val);
+      }
+    else
+      val = Vcoding_system_for_read;
     if (NILP (val))
       {
-	SAFE_ALLOCA_LISP (args2, nargs + 1);
-	args2[0] = Qstart_process;
-	for (i = 0; i < nargs; i++) args2[i + 1] = args[i];
+	ptrdiff_t nargs2 = 3 + XINT (Flength (command));
+	Lisp_Object tem2;
+	SAFE_ALLOCA_LISP (args2, nargs2);
+	i = 0;
+	args2[i++] = Qstart_process;
+	args2[i++] = name;
+	args2[i++] = buffer;
+	for (tem2 = command; CONSP (tem2); tem2 = XCDR (tem2))
+	  args2[i++] = XCAR (tem2);
 	GCPRO2 (proc, current_dir);
 	if (!NILP (program))
-	  coding_systems = Ffind_operation_coding_system (nargs + 1, args2);
+	  coding_systems = Ffind_operation_coding_system (nargs2, args2);
 	UNGCPRO;
 	if (CONSP (coding_systems))
 	  val = XCAR (coding_systems);
@@ -1470,17 +1531,31 @@ usage: (start-process NAME BUFFER PROGRAM &rest PROGRAM-ARGS)  */)
       }
     pset_decode_coding_system (XPROCESS (proc), val);
 
-    val = Vcoding_system_for_write;
+    val = Qnil;
+    if (!NILP (tem))
+      {
+	val = XCAR (XCDR (tem));
+	if (CONSP (val))
+	  val = XCDR (val);
+      }
+    else
+      val = Vcoding_system_for_write;
     if (NILP (val))
       {
 	if (EQ (coding_systems, Qt))
 	  {
-	    SAFE_ALLOCA_LISP (args2, nargs + 1);
-	    args2[0] = Qstart_process;
-	    for (i = 0; i < nargs; i++) args2[i + 1] = args[i];
+	    ptrdiff_t nargs2 = 3 + XINT (Flength (command));
+	    Lisp_Object tem2;
+	    SAFE_ALLOCA_LISP (args2, nargs2);
+	    i = 0;
+	    args2[i++] = Qstart_process;
+	    args2[i++] = name;
+	    args2[i++] = buffer;
+	    for (tem2 = command; CONSP (tem2); tem2 = XCDR (tem2))
+	      args2[i++] = XCAR (tem2);
 	    GCPRO2 (proc, current_dir);
 	    if (!NILP (program))
-	      coding_systems = Ffind_operation_coding_system (nargs + 1, args2);
+	      coding_systems = Ffind_operation_coding_system (nargs2, args2);
 	    UNGCPRO;
 	  }
 	if (CONSP (coding_systems))
@@ -1512,10 +1587,10 @@ usage: (start-process NAME BUFFER PROGRAM &rest PROGRAM-ARGS)  */)
 	  && !(SCHARS (program) > 1
 	       && IS_DEVICE_SEP (SREF (program, 1))))
 	{
-	  struct gcpro gcpro1, gcpro2, gcpro3, gcpro4;
+	  struct gcpro gcpro1, gcpro2;
 
 	  tem = Qnil;
-	  GCPRO4 (name, program, buffer, current_dir);
+	  GCPRO2 (buffer, current_dir);
 	  openp (Vexec_path, program, Vexec_suffixes, &tem,
 		 make_number (X_OK), false);
 	  UNGCPRO;
@@ -1534,31 +1609,32 @@ usage: (start-process NAME BUFFER PROGRAM &rest PROGRAM-ARGS)  */)
       tem = remove_slash_colon (tem);
 
       {
-	Lisp_Object arg_encoding = Qnil;
+	Lisp_Object arg_encoding = Qnil, tem2;
 	struct gcpro gcpro1;
+
+	tem = Fcons (tem, Fcopy_sequence (XCDR (command)));
 	GCPRO1 (tem);
 
 	/* Encode the file name and put it in NEW_ARGV.
 	   That's where the child will use it to execute the program.  */
-	tem = list1 (ENCODE_FILE (tem));
+	XSETCAR (tem, ENCODE_FILE (XCAR (tem)));
 
 	/* Here we encode arguments by the coding system used for sending
 	   data to the process.  We don't support using different coding
 	   systems for encoding arguments and for encoding data sent to the
 	   process.  */
 
-	for (i = 3; i < nargs; i++)
+	for (tem2 = XCDR (tem); CONSP (tem2); tem2 = XCDR (tem2))
 	  {
-	    tem = Fcons (args[i], tem);
-	    CHECK_STRING (XCAR (tem));
-	    if (STRING_MULTIBYTE (XCAR (tem)))
+	    CHECK_STRING (XCAR (tem2));
+	    if (STRING_MULTIBYTE (XCAR (tem2)))
 	      {
 		if (NILP (arg_encoding))
 		  arg_encoding = (complement_process_encoding_system
 				  (XPROCESS (proc)->encode_coding_system));
-		XSETCAR (tem,
+		XSETCAR (tem2,
 			 code_convert_string_norecord
-			 (XCAR (tem), arg_encoding, 1));
+			 (XCAR (tem2), arg_encoding, 1));
 	      }
 	  }
 
@@ -1567,10 +1643,11 @@ usage: (start-process NAME BUFFER PROGRAM &rest PROGRAM-ARGS)  */)
 
       /* Now that everything is encoded we can collect the strings into
 	 NEW_ARGV.  */
-      SAFE_NALLOCA (new_argv, 1, nargs - 1);
-      new_argv[nargs - 2] = 0;
+      new_argc = XINT (Flength (tem));
+      SAFE_NALLOCA (new_argv, 1, new_argc + 1);
+      new_argv[new_argc] = 0;
 
-      for (i = nargs - 2; i-- != 0; )
+      for (i = 0; i < new_argc; i++)
 	{
 	  new_argv[i] = SDATA (XCAR (tem));
 	  tem = XCDR (tem);
@@ -1581,6 +1658,7 @@ usage: (start-process NAME BUFFER PROGRAM &rest PROGRAM-ARGS)  */)
   else
     create_pty (proc);
 
+  UNGCPRO;
   SAFE_FREE ();
   return unbind_to (count, proc);
 }
@@ -1648,7 +1726,7 @@ create_process (Lisp_Object process, char **new_argv, Lisp_Object current_dir)
 
   inchannel = outchannel = -1;
 
-  if (!NILP (Vprocess_connection_type))
+  if (p->pty_flag)
     outchannel = inchannel = allocate_pty (pty_name);
 
   if (inchannel >= 0)
@@ -1894,7 +1972,7 @@ create_pty (Lisp_Object process)
 {
   struct Lisp_Process *p = XPROCESS (process);
   char pty_name[PTY_NAME_SIZE];
-  int pty_fd = NILP (Vprocess_connection_type) ? -1 : allocate_pty (pty_name);
+  int pty_fd = !p->pty_flag ? -1 : allocate_pty (pty_name);
 
   if (pty_fd >= 0)
     {
@@ -7269,6 +7347,8 @@ syms_of_process (void)
   DEFSYM (QCstop, ":stop");
   DEFSYM (QCoptions, ":options");
   DEFSYM (QCplist, ":plist");
+  DEFSYM (QCcommand, ":command");
+  DEFSYM (QCconnection_type, ":connection-type");
 
   DEFSYM (Qlast_nonmenu_event, "last-nonmenu-event");
 
@@ -7371,7 +7451,7 @@ The variable takes effect when `start-process' is called.  */);
   defsubr (&Sprocess_plist);
   defsubr (&Sset_process_plist);
   defsubr (&Sprocess_list);
-  defsubr (&Sstart_process);
+  defsubr (&Smake_process);
   defsubr (&Sserial_process_configure);
   defsubr (&Smake_serial_process);
   defsubr (&Sset_network_process_option);
-- 
2.1.0