update

Void. This is an empty function by default, but can be overridden in the respondent of a form, to do some processing after the respondent's write-html-sheet function runs to present the object.

Void. This is an empty function by default, but can be overridden in the requestor of a form, to do some processing after the requestor's form values are set into the specified bashee.

GDL Instance. In an element of a sequence, this is the container object which holds all elements.

List of Symbols. Lists all the superclasses of the type of this object.

GDL Object. Object to have its settable computed-slots and/or query-plist set from the fields on the form upon submission. Defaults to self.

Void. This is an empty function by default, but can be overridden in the respondent of a form, to do some processing before the respondent's write-html-sheet function runs to present the object. This can be useful especially for objects which are subclasses of higher-level mixins such as application-mixin and node-mixin, where you do not have direct access to the write-html-sheet function and typically only define the model-inputs function. It is not always reliable to do processing in the model-inputs function, since some slots which depend on your intended modifications may already have been evaluated by the time the model-inputs function runs.

Void. This is an empty function by default, but can be overridden in a user specialization of base-html-sheet, to do some processing before the header-plist is evaluated and before the HTTP response is actually initiated.

Void. This is an empty function by default, but can be overridden in the requestor of a form, to do some processing before the requestor's form values are set into the specified bashee.

NIL or error object. This function checks the "sanity" of this object. By default, it checks that following the object's root-path from the root resolves to this object. If the act of following the root-path throws an error, this error will be returned. Otherwise, if the result of following the root-path does not match the identity of this object, an error is thrown indicating this. Otherwise, NIL is returned and no error is thrown. You can override this function to do what you wish. It should return NIL if the object is found to be "sane" and an throw an error otherwise.

If check-sanity? is set to T in this object, this function will be invoked automatically within an ignore-errors by the function handling the GWL "/answer" form action URI when this object is a respondent, before the main-sheet is presented.

Boolean. Determines whether a a sanity check is done (with the check-sanity function) before presenting the response page if this page is a respondent. Default is NIL.

List of GDL Instances. All objects from the :objects specification, including elements of sequences as flat lists.

List of GDL Instances. All objects from the :objects specification, including elements of sequences as flat lists.

List of Symbols. Lists the direct superclasses of the type of this object.

Plist. Returns the :documentation plist which has been specified the specific part type of this instance.

String. This is the auto-computed dom-id which should be used for rendering this section. If you use the main-div HTML string for rendering this object as a page section, then you do not have to generate the :div tag yourself - the main-div will be a string of HTML which is wrapped in the correct :div tag already.

List of GDL objects. All the form-controls which do not pass validation.

Boolean. For elements of sequences, T iff there is no previous element.

GDL Instance. Using this instance as the root, follow the reference chain represented by the given path. :arguments (path "List of Symbols or Pairs of Symbol and Integer")

List of GDL objects of type form-control. The validation-function will be forced on these objects when a form is submitted, even if the object's html form-control does not happen to be included in the values submitted with the form. Defaults to nil.

List of GDL objects. All the children or hidden-children of type base-form-control.

String of HTML. The value of the computed-slot named by KEY (a keyword) wrapped in a div carrying the fragment's auto dom-id, so a gdlAjax call can replace its innerHTML without the content living in a base-html-div child section. List KEY in html-fragments to participate in ajax responses. [gornskew 2026-07-20]

String.

This function returns a string of Javascript, appropriate to use for events such as :onclick, :onchange, etc, which will invoke an Ajax request to the server, which will respond by replacing the innerHTML of affected :div's, and running the Javascript interpreter to evaluate (the js-to-eval), if any.

:examples "

 FLAG -- Fill in!!!

"

:&key ((bashee (the bashee)) "GDL Object. This object will have the function-key called on it, if any." (respondent (the respondent)) "GDL Object. This must be the object which represents the actual web page being used." (function-key nil) "Keyword symbol. This keyword symbol must name a GDL function or method which is to be invoked with the Ajax call." (arguments nil) "List of values. This is the argument list on which the function named by function-key will be applied." (form-controls nil) "List of GDL objects of type base-form-control. Each of the objects in this list will have its current value (as entered by the user) scraped from the web page and its value in the model "bashed" to reflect what has been entered on the page.")

Plist. Extra http headers to be published with the URI for this page.

List of GDL Instances. All objects from the :hidden-objects specification, including elements of sequences as flat lists.

Boolean. Indicates whether the object should effectively be a hidden-object even if specified in :objects. Default is nil.

List of keyword symbols, naming computed-slots of this sheet whose values are HTML strings rendered at toplevel via fragment-div. Usually UNNECESSARY: fragment-div self-registers each key it renders (monotonically, outside the KB), so this list is only for extra keys not (yet) rendered through fragment-div on this sheet. Any listed fragment whose slot-status is :invalidated at gdlAjax response time gets recomputed and its innerHTML replaced in the browser -- no base-html-div child section required. [gornskew 2026-07-20]

List of HTML sections to be scanned and possibly replaced in response to GDL Ajax calls. Override this slot at your own risk. The default is all sections who are most recently laid out on the respondent sheet, and this is set programmatically every time the sheet section's main-div is demanded.

List of valid HTML sections to be scanned and possibly replaced in response to GDL Ajax calls. Override this slot at your own risk. The default is all sections who are most recently laid out on the respondent sheet, and this is set programmatically every time the sheet section's main-div is demanded.

Integer. Sequential index number for elements of a sequence, NIL for singular objects.

String. This can be used with (str ...) [in cl-who] or (:princ ...) [in htmlGen] to output this section of the page, without the wrapping :div tag [so if you use this, your code would be responsible for wrapping the :div tag with :id (the dom-id).]

String of valid Javascript. This Javascript will be send with the Ajax response, and evaluated after the innerHTML for this section has been replaced.

Boolean. For elements of sequences, T iff there is no next element.

Boolean. T if this object has no children, NIL otherwise.

List of GDL Objects. A Collection of the leaf nodes of the given object.

List of GDL Objects. A Collection of the leaf nodes of the given object.

String. This should be used with (str ...) [in cl-who] or (:princ ...) [in htmlGen] to output this section of the page, including the wrapping :div tag.

String. This is synonymous with slot-documentation

List of Keyword Symbols. Returns the messages (slots, objects, and functions) of this object, according to the filtering criteria as specified by the arguments. :&key ((category :all) "Keyword. Either :all or the individual category of messages to be returned. This can be one of:

• :computed-slots

• :settable-computed-slots

• :required-input-slots

• :optional-input-slots

• :defaulted-input-slots

• :query-slots

• :functions

• :objects

• :quantified-objects

• :hidden-objects

• :quantified-hidden-objects

" (message-type :global) "Keyword Symbol, :local or :global. Indicates whether to return messages only from the local specific part type, or from all superclasses (mixins) as well." (return-category? nil) "Boolean. Indicates whether or not the category of each message should be returned before each message in the returned list." (base-part-type nil) "Symbol naming a GDL Part Type. Indicates a "base" part from which no messages should be returned, nor should messages be returned from superclasses (mixins) of this base part. If NIL (the default), messages are considered from all superclasses." (sort-order :unsorted) "Keyword Symbol. One of: :unsorted, :by-category, or :by-name." (filter :normal) "Function Object of two arguments or :normal. If a function object, applies this function to each returned category and message keyword, and filters out all pairs for which the function returns NIL. If :normal (the default), then no filtering is done.")

List of Symbols. Returns the names of the immediate superclasses of this object.

:&key ((local? t) "Boolean. Indicates whether to give only direct mixins or all mixins from the entire inheritance hierarchy.")

Keyword symbol. The part's simple name, derived from its object specification in the parent or from the type name if this is the root instance.

GDL Instance. For elements of sequences, returns the next part in the sequence.

List of GDL objects, which should be of type 'base-form-control.

[Note -- this slot is not really necessary for protecting out-of-bounds sequence references anymore, the form-control processor protects against this by itself now].

These objects are validated and bashed first, in the order given. If the cardinality of one form-control depends on another as in the example below, then you should list those dependent objects first. Default is nil.

:examples

 
...
  
  :computed-slots ((number-of-nozzles (the number-of-nozzles-form value))
        (ordered-form-controls 
         (append (list-elements (the inner-flange-form))
             (list (the number-of-nozzles-form)))))
  
  :objects
  ((inner-flange-form
    :type 'menu-form-control 
    :choice-plist (list :hey "hey" :now "now")
    :default :hey
    :sequence (:size (the number-of-nozzles)))

   (number-of-nozzles-form
    :type 'text-form-control 
    :prompt "Number of Shell Nozzles Required: "
    :domain :number     
    :default 0)

GDL Instance. The parent of this object, or NIL if this is the root object.

List of keyword symbols. Messages corresponding to form fields which could be missing from form submission (e.g. checkbox fields). Defaults to the names of any children or hidden-children of type menu-form-control or checkbox-form-control.

Boolean. This switch determines whether all form-controls should be preset before the final setting, in order to allow any interdependencies to be detected for validation or detecting changed values. If this is specified as a non-nil value, then any nil values of (the preset?) on individual form controls will be ignored. If this is specified as nil, then (the preset?) of individual form-controls (default of these is also nil) will be respected. Default is nil.

GDL Instance. For elements of sequences, returns the previous part in the sequence.

Void. This is an empty function by default, but can be overridden in a user specialization of base-html-sheet, to do some processing before the header-plist is evaluated and before the HTTP response is actually initiated, but after the cookies-received have been set.

Plist. Contains submitted form field names and values for which no corresponding settable computed-slots exist. Where corresponding settable computed-slots exist, their values are set from the submitted form fields automatically.

GDL Object. Object to respond to the form submission. Defaults to self.

Void. Restores all settable-slots in this instance to their default values.

Void. Calls restore-defaults! on all the form-controls in this sheet.

Multiple Values: Total root-paths affected and total slots affected. Reverts any "remembered" bashed slots, starting from the root, to their default values. Note that any call to set-slot! or set-slots! or any use of web form-controls will result in "remembered values". Note that there is a :remember? keyword argument to set-slot! which defaults to t but if you specify it as nil, you can bash values without having them "remembered" and such slots would not be affected by this function.

NIL. Restores the value of the given slot to its default, thus "undoing" any forcibly set value in the slot. Any dependent slots in the tree will respond accordingly when they are next demanded. Note that the slot must be specified as a keyword symbol (i.e. prepended with a colon (":")), otherwise it will be evaluated as a variable according to normal Lisp functional evaluation rules. :arguments (slot "Keyword Symbol") :key (force? "Boolean. Specify as t if you want to force non-settable slots to recompute (e.g. reading from databases or external files). Defaults to nil.")

nil. Restores the value of the given slots to their defaults, thus "undoing" any forcibly set values in the slots. Any dependent slots in the tree will respond accordingly when they are next demanded. Note that the slots must be specified as keyword symbols (i.e. prepended with colons (":")), otherwise they will be evaluated as variables according to normal Lisp functional evaluation rules.

:arguments (slots "List of Keyword Symbols")

:&key ((force? force-restore-slot-default?) "Boolean. Indicates whether the slot values should be unbound, regardless of whether it had actually been bashed previously.")

Void. Restores all settable-slots in this instance, and recursively in all descendant instances, to their default values.

GDL object. Default object to which control will return with the write-back-link method

GDL Instance. The root-level node in this object's "tree" (instance hierarchy).

List of Symbols or of Pairs of Symbol and Integer. Indicates the path through the instance hierarchy from the root to this object. Can be used in conjunction with the follow-root-path GDL function to return the actual instance.

List of Symbols or of Pairs of Symbol and Integer. Indicates the path through the instance hierarchy from the local root to this object. Can be used in conjunction with the follow-root-path GDL function to return the actual instance.

Boolean. T iff this part has NIL as its parent and therefore is the root node.

List of GDL Instances. All objects from the :objects specification, including elements of sequences as flat lists. Any children which throw errors come back as a plist with error information

List of GDL Instances. All objects from the :hidden-objects specification, including elements of sequences as flat lists. Any children which throw errors come back as a plist with error information

Void. Emits a page explaining the sanity error. This will be invoked instead of the write-main-sheet if check-sanity? is set to T and the check-sanity throws an error. You may override this function to do what you wish. By default a minimal error message is displayed and a link to the root object is presented.

:arguments (error "an error object, presumably from the check-sanity function.")

Void. Writes an HTML Select field with Options. :&key ((size 1) "Integer. determines size of selection list. Default of 1 is a pulldown menu." name "Keyword symbol or string. Determines the name of the field, which should probably match a settable computed-slot." keys "List of strings, numbers, or symbols. Values, the selected one of which will be returned as the value of the field." (values keys) "List of strings. Keys to display in the selection-list." tabindex "Integer. If given, this will generate the tabindex tag for this HTML input field.")

NIL. Forcibly sets the value of the given slot to the given value. The slot must be defined as :settable for this to work properly. Any dependent slots in the tree will respond accordingly when they are next demanded. Note that the slot must be specified as a keyword symbol (i.e. prepended with a colon (":")), otherwise it will be evaluated as a variable according to normal Lisp functional evaluation rules.

Note also that this must not be called (either directly or indirectly) from within the body of a Gendl computed-slot. The caching and dependency tracking mechanism in Gendl will not work properly if this is called from the body of a computed-slot, and furthermore a runtime error will be generated.

:arguments (slot "Keyword Symbol" value "Lisp Object. (e.g. Number, String, List, etc.)")

:&key ((remember? t) "Boolean. Determines whether to save in current version-tree." (warn-on-non-toplevel? t) "Boolean. Determines whether to warn if this is called from the body of a cached slot." )

NIL. Forcibly sets the value of the given slots to the given values. The slots must be defined as :settable for this to work properly. Any dependent slots in the tree will respond accordingly when they are next demanded. Note that the slots must be specified as a keyword symbols (i.e. prepended with a colon (":")), otherwise they will be evaluated as variables according to normal Lisp functional evaluation rules. :arguments (slots-and-values "Plist. Contains alternating slots and values to which they are to be set." warn-on-non-toplevel? "Boolean. Indicates whether a warning should be issued for calling from inside the body of a cached slot. Default is t.")

Plist of Symbols and Strings. Returns the part types and slot documentation which has been specified for the given slot, from most specific to least specific in the CLOS inheritance order. Note that the slot must be specified as a keyword symbol (i.e. prepended with a colon (":")), otherwise it will be evaluated as a variable according to normal Lisp functional evaluation rules. :arguments (slot "Keyword Symbol. Names the slot for which documentation is being requested.")

Body of GDL code, in list form.

:arguments (slot "Keyword Symbol. Names the slot for which documentation is being requested.")

Keyword symbol. Describes the current status of the requested slot:

• :unbound: it has never been demanded.

• :invalidated: it was demanded at some point, but something it depends on has been modified since; it is currently unbound and will be re-evaluated on next demand.

• :evaluated: it has been demanded and it is currently bound to the default value based on the code.

• :set: (for :settable slots only, which includes all required :input-slots) it has been modified and is currently bound to the value to which it was explicitly set.

• :toplevel: (for root-level object only) its value was passed into the root-level object as a toplevel input at the time of object instantiation.

String or List of Strings. Determines how the name of objects of this type will be printed in most places. This defaults to the name-for-display (generally the part's name as specified in its parent), followed by an index number if the part is an element of a sequence.

String. Name of a browser frame or window to display this page. Default of NIL indicates to use the same window.

Void. Sets giving slot to its boolean opposite. &args (slot "Keyword symbol. Name of the slot as a keyword symbol.")

List of keyword symbols. Messages corresponding to form fields which should not be retained against Updates to the model (e.g. calls to the update! function or hitting the Update button or link in the browser in development mode). Defaults to NIL (the empty list).

Symbol. The GDL Type of this object.

Void. Uncaches all cached data in slots and objects throughout the instance tree from this node, forcing all code to run again the next time values are demanded. This is useful for updating an existing model or part of an existing model after making changes and recompiling/reloading the code of the underlying definitions. Any set (modified) slot values will, however, be preserved by the update.

String. The canonical web address in the current session which points at this page. Also see full-url. Published on demand.

List of GDL Instances. Additional objects to display in Tatu tree. Typically this would be a subset of hidden-children. Defaults to NIL.

Void. Creates a default unordered list with links to each child part of self. The text of the links will come from each child's strings-for-display.

Void. Writes links for access to the standard developer views of the object, currently consisting of an update (Refresh!) link, a Break link, and a ta2 link.

Void. This GDL function should be redefined to generate the HTML page corresponding to this object. It can be specified here, or as the main-sheet output-function in an html-format lens for this object's type. This write-html-sheet function, if defined, will override any main-sheet function defined in the lens. Typically a write-html-sheet function would look as follows:

:example

 (write-html-sheet
  ()
  (html (:html (:head (:title (:princ (the :page-title))))
               (:body ;;; fill in your body here

               ))))

Void. Emits a hyperlink pointing to self. Note that if you need extra customization on the display-string (e.g. to include an image tag or other arbitrary markup), use with-output-to-string in conjunction with the html-stream macro.

:&key ((display-string (the :strings-for-display)) "String. String to be displayed." (display-color nil) "Keyword symbol or HTML color string. Determines the color of the displayed link text. Default of NIL indicates web browser default (usually blue)." (target (the :target)) "String. Names a frame or window to open the link when clicked." (class nil) "String. Names a stylesheet class." (id nil) "String. Names a stylesheet id." (on-mouse-over nil) "String. Javascript code to run on mouse over." (on-mouse-out nil) "String. Javascript code to run on mouse out.")

Void. Writes a file containing the toplevel inputs and modified settable-slots starting from the root of the current instance. Typically this file can be read back into the system using the read-snapshot function.

:&key ((filename "/tmp/snap.gdl") "String or pathname. The target file to be written." (root-paths-to-ignore nil) "List of root-paths or nil. Any objects with matching root-path will be ignored for the snapshot write." )

Void. Writes some standard footer information. Defaults to writing Genworks and Franz copyright and product links. Note that VAR agreements often require that you include a "powered by" link to the vendor on public web pages.