Hi Alex,

>> 1. What is the purpose of calling (wait) after (server 8080 "...")? It
>> will "wait" for what? What is the differences if (wait) is not called?
> In this case (when called without any arguments), 'wait' will wait for
> an infinite time (see also "doc/refW.html#wait"). The purpose is to
> inhibit PicoLisp from dropping into a read-eval loop when 'server'
> received a connect. This is opposed to debugging mode where you don't
> call that 'wait', and instead want to debug the GUI session.

OK. Thanks.

>> 2. Could you explain how does "ht:" magic work?
>>    : ht:Prin
>>    -> NIL
>>    : (ht:Prin "xxx")
>>    xxx-> T
> 'ht:Prin' is a normal symbol and thus has a value of NIL initially. If
> such a symbol is called as a function, it would usually cause an error:
>    : abc
>    -> NIL
>    : (abc "xxx")
>    !? (abc "xxx")
>    abc -- Undefined
> However, when the "Undefined" error handling routine of PicoLisp detects
> that the name of that undefined symbol contains a colon, it tries to
> locate a shared object library (DLL) with the name before the colon
> (here 'ht'), and searches for a symbol with the name after the colon
> (here 'Prin'). If it finds such a symbol, it "defines" the Lisp symbol
> 'ht:Prin' so that from now on it is just like any other function written
> in C:
>    : ht:Prin
>    -> NIL               # Not defined
>    : (ht:Prin "xxx")    # Calling it
>    xxx-> T
>    : ht:Prin
>    -> 1540706488        # Now it is defined
>>    : (ht:abc)
>>    ht:abc -- /usr/local/picoLisp/lib/ht: undefined symbol: abc
> So this failed, as the 'ht' library does not contain 'abc'.

OK. Can the "Undefined error handling" be defined/extended/overridden
at Lisp (not C) level? Something like Ruby's const_missing() and

>> 3. In the "Alerts and Dialogs" example in doc/app.html, there is a
>> call (dispose (: home top 1))
> Oops, you found an error in the documentation! The function 'dispose'
> does not exist any more. It is now implicit in the 'yesButton'. So the
> example should look like:
>    '(alert NIL "Are you sure? "
>       (yesButton
>          '(set> (: home top 2 gui 1)
>             (val> (: home top 1 gui 1)) ) )
>       (noButton) ) )
> I fixed it, and uploaded a corrected version to the testing release.
>> which is meant to remove enclosing form
>> (right?), but the problem is that 'dispose' does not exist!
> To be precise, it is meant to remove the dialog from above the form. On
> a page, there may be any numbers of forms, and above these forms may be
> any number of "pop up" dialogs. These dialogs usually have some buttons
> like "close", "yes", "no" etc. which may or may not close them.
> Instead of the 'dispose' function, dialogs are now closes by the
> '+Close' prefix class to those buttons. For example, the 'yesButton'
> looks like:
>    (de yesButton (Exe)
>       (gui '(+Close +Button) ',"Yes" Exe) )
> i.e. it creates a button which inherits the close behavior from
> '+Close', and which is labelled "Yes". When that button is pressed, the
> expression 'Exe' is executed (the (set> ...)) above, and the dialog (or
> alert) is closed.

OK. But it will close only the "alert" (the enclosing "form" of the
button), not the "dialog" (parent "form" of the alert). To close the
dialog, the user must press the cancel button, after the alert was
closed. Isn't (dispose (: home top 1)) trying to close the "dialog"?
Is it possible to do so?

>> 4. What is 'Dn' in (dm set> (Val Dn) ...)? For what?
> This is an internal parameter to the 'set>' method of GUI components. It
> is not used on the application level. IIRC, it means "down", and is used
> in "charts" (two-dimensional tables of GUI components) to avoid infinite
> recursion when setting the values of those components. This is because
> setting the value of such a components will trigger the setting of the
> value of the whole chart, and setting the value of a chart will trigger
> the setting of the values of its individual components.

OK. By the way, is there a "reference-style" documentation for GUI
(e.g. +gui, +Chart) and Database (e.g. +Entity, +Relation), something
like the useful "Pico Lisp Reference" (ref.html)? The source code has
"sparse" comments, if any! ;-)

Best regards,
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