[Openmcl-devel] How to use lisp program in unix pipeline

Frank Sonnemans openmcl at sonnemans.net
Tue May 13 09:31:29 UTC 2003


Gary,

Thanks for the exhaustive reply. From what you write I have another scenario
in mind. Instead of having many multi megabyte images I can create one
specialized image which does nothing but load a fasl (or lisp) file which is
the first commandline parameter, call a sort of main function which gets the
rest of the commandline options as a parameter and exit. This way openmcl
would behave like a shell executing a shell script on steroids.

Regards,

Frank
On 2003-12-5 16:42, "Gary Byers" <gb at clozure.com> wrote:

> 
> 
> On Mon, 12 May 2003, Frank Sonnemans wrote:
> 
>> Hello all,
>> 
>> I wrote a small lisp application which takes an xml file, filters it and
>> writes a html file. What I now want to do is use this lisp application in
>> several ways:
>> 
>> Myfilter infile outfile
>> 
>> Or
>> 
>> Myfilter < infile > outfile
>> 
>> Or
>> 
>> Cat infile | Myfilter > outfile
>> 
>> How do I do this with openmcl. As the startup time of openmcl is very short
>> I would basically like to use it to replace my unreadable perl scripts.
>> 
>> So far I got some results using a construct like:
>> 
>> Cat Myfilter.lisp | openmcl -b
> 
> The support that exists for creating applications (especially applications
> that don't behave like lisp development systems) is poorly modularized,
> mostly undocumented, and in some cases poorly implemented.  (Other than
> that, it's just fine.)
> 
> The general idea is that there's a CLOS class called CCL::APPLICATION
> (and an interesting subclass of that class, called
> CCL::LISP-DEVELOPMENT-SYSTEM); the special variable CCL:*APPLICATION*
> is assumed to be bound to an instance of some type of APPLICATION
> object, and certain application-specific behaviors (how arguments
> are processed, how errors are handled, how command-line arguments
> are processed) are determined by calling generic functions which
> have methods specialized on the current application class (the value
> of CCL:*APPLICATION*.)
> 
> The function SAVE-APPLICATION is ordinarily used to write a heap
> image file (either the initial "dppccl.image"/"PPCCL" image created
> during bootstrapping or a lisp image that's been customized and/or
> augmented in some way.)  SAVE-APPLICATION additionally takes an
> :APPLICATION-CLASS argument, whose value can be a class (presumed
> to be a subclass of APPLICATION) or the name of such a class.
> SAVE-APPLICATION arranges that when the saved image starts up,
> *APPLICATION* will be bound to an instance of  that specified class
> and will start up and behave according to methods specialized on
> that class.
> 
> As straightforward as that might sound, reality's a lot messier:
> there are some obviously customizable behaviors that don't go through
> the *APPLICATION* protocol, there are ways of customizing behavior
> that conflict with it, and there are probably things in
> LISP-DEVELOPMENT-SYSTEM that should be in APPLICATION and things
> in APPLICATION (or outside the protocol) that are probably specific
> to LISP-DEVELOPMENT-SYSTEM.
> 
> The only example of any of this that I can think of is in
> "ccl:examples;cocoa-application": it says that a COCOA-APPLICATION
> (perhaps it'd be better to call it a COCOA-LISP-DEVELOPMENT-SYSTEM)
> is a LISP-DEVELOPMENT-SYSTEM that doesn't try too hard to parse its
> command-line arguments (when launched from the Finder, an application's
> sole (?) argument is of the form "-psn_XXXX" : a process serial number
> used to register the application with the window server.)
> 
> Some command-line arguments (things having to do with memory initialization
> and with specifying the heap image to load, mostly) are processed by
> the lisp kernel.  Those arguments that the kernel doesn't handle (including
> argv[0], the kernel pathnmame) are used to initialize the variable
> CCL::*COMMAND-LINE-ARGUMENT-LIST*.
> 
> When an application starts up, it does some initialization (some of
> which could maybe be - but isn't - governed by *APPLICATION*) and then
> calls the application's TOPLEVEL-FUNCTION method with the value
> returned by calling the application's INIT-FILE method as an argument.
> The TOPLEVEL-FUNCTION method for APPLICATION (defined in
> "ccl:level-1;l1-readloop.lisp") parses and then processes the
> command-line arguments.  An APPLICATION subclass is presumed to
> have a COMMAND-LINE-ARGUMENTS instance variable, which is a getopt-like
> table that defines the arguments that the application recognizes.
> 
> 
> 
>> 
>> Problem is that openmcl outputs it's welcome message and prompt before the
>> output of my lisp program (see bottom of this message for example). This is
>> unsuitable for the type of use I have in mind. Can I suppress the prompt and
>> welcome message?
> 
> The TOPLEVEL-FUNCTION method for LISP-DEVELOPMENT-SYSTEM does
> a CALL-NEXT-METHOD to handle the arguments, then runs some code
> which finishes argument processing and then starts a read-eval-print
> loop.  The "Welcome ..." banner gets printed unless the variable
> CCL::*INHIBIT-GREETING* is set.
> 
> It arguably doesn't make much sense for the read-eval-print loop
> to print a prompt if the -b/--batch option is in effect; there's
> currently no easy way to suppress the printing of the prompt.
> 
> One could argue that the -b flag basically affects the behavior
> of LISP-DEVELOPMENT-SYSTEM.  It's actually processed by the kernel,
> in the belief that it affects how some standard streams are initialized
> and therefore has to be handled early.  (It's desirable that streams
> be initialized as early as possible, so that errors don't go into the
> Stack Overflow Death Spiral: it's very hard to tell you that *ERROR-OUTPUT*
> isn't a valid stream without trying to write to *ERROR-OUTPUT*)
> 
>> 
>> Secondly how do I access the command line parameters from my lisp program?
>> 
> 
> The built-in stuff uses the PARSE-APPLICATION-ARGUMENTS and PROCESS-
> APPLICATION-ARGUMENTS.  PARSE-APPLICATION-ARGUMENTS returns 3 values:
> an indication of whether or not an error occurred during parsing,
> a "normalized" list of option specifiers and associated parameters,
> and a list of any other arguments that aren't associated with options.
> (As a LISP-DEVELOPMENT-SYSTEM, OpenMCL doesn't accept any such
> "other arguments"; the idea is that some other application classes
> might.
> 
> PROCESS-APPLICATION-ARGUMENTS takes the values returned by PARSE-
> APPLICATION-ARGUMENTS as its arguments.  The method specialized
> on the class APPLICATION exits with a "USAGE" message if an error
> was returned from the parser of if the --help option was present.
> The PROCESS-APPLICATION-ARGUMENTS method for LISP-DEVELOPMENT-SYSTEM
> does some checking and uses the options returned by the parser
> to set some special variables that're referenced later in the
> startup process.
> 
> I don't believe that there's currently any way for an application
> subclass to inherit command-line argument specifiers from its
> superclasses.  That's kind of stupid: it may mean that a subclass
> of LISP-DEVELOPMENT-SYSTEM that wants to add an argument or two
> has to copy LISP-DEVELOPMENT-SYSTEM's COMMAND-LINE-ARGUMENTS
> instance variable and push a thing or two on it.
> 
> If this protocol is inappropriate, you can avoid it by making
> a PARSE-APPLICATION-ARGUMENTS method that returns three NIL
> values and accessing CCL::*COMMAND-LINE-ARGUMENTS-LIST* later
> in your TOPLEVEL-FUNCTION method.
> 
>> Regards,
>> 
>> 
>> Frank
>> 
>> Example command line session showing openmcl printing prompt:
>> 
>> [Frank-Sonnemanss-Computer:~] frank% cat test.lisp
>> (print "hello world")
>> [Frank-Sonnemanss-Computer:~] frank% cat test.lisp | openmcl -b
>> Welcome to OpenMCL Version (Beta: Darwin) 0.13.4!
>> ?
>> "hello world"
>> "hello world"
>> 
> 
> It's possible to suppress the banner, and it should be possible
> to suppress the r-e-p-l's prompt (perhaps via the --batch option.)
> 
> It sounds like your XML-HTML filter doesn't really want or need
> the read-eval-print loop.
> 
> You -should- therefore be able to do something like:
> 
> (defclass xml-html-filter (ccl::application) ())
> 
> (defmethod ccl::toplevel-function ((app xml-html-filter) init-file)
> (declare (ignore init-file))
> ;;
> (let* ((parsed-xml-object (read-xml-file *standard-input)))
>    (write-html-file parsed-xml-file *standard-output*)))
> 
> (defmethod ccl::application-error ((app xml-html-filter)
>                                  condition error-pointer)
> (declare (ignore error-pointer)) ;; the stack frame where the error occurred
> (format *error-output* "~&Fatal error: ~a" condition)
> (quit -1))
> 
> ? (save-application "xml-html-filter.image"
>    :application-class 'xml-html-filter)
> 
> % openmcl xml-html-filter.image <xmlfile >htmlfile
> 
> The operative word is "should": I can't think of a reason that would
> prevent that from working, but don't trust this stuff 100% and would
> not be shocked if such a reason existed.
> 
> 
>> 
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>> 
>> 
> 


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