Paolo Amoroso's Journal

WebCard has very limited control over the web browser of the host operating system.

It can only command the browser to visit a URL when the user traverses a Web link or executes the Visit URL menu command. But with no precautions the browser would open a new tab for every visit of the same URL.

To reduce clutter I tweaked WebCard to keep track of visited URLs. The URLVisitedP boolean property of a Web card window indicates whether the associated URL was already visited. The function WCD.TraverseWebLink checks URLVisitedP and visits the URL only if the property is NIL, then sets it to T if it does visit the URL. URLVisitedP is a property of the window rather than the card because, as part of the dynamic session state, NoteCards shouldn't save it in notefiles.

The overall behavior of Web cards and URL visits appears as follows.

Traversing the link of a closed Web card unconditionally visits the URL. Once the card is open, traversing the link again flashes the card to call attention to it but doesn't visit the URL. The Visit URL menu command can force the visit though. Closing a card sets URLVisitedP to NIL, so the next time link traversal reopens the card it triggers a visit.

This should take care of the most common cases of unintentional link traversal, reduce tab clutter, and prepare WebCard for actual usage.

#WebCard #Interlisp #Lisp

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In NoteCards, Text cards are rectangular windows with proportions similar to a post-it note. The Web card type of WebCard inherits from Text, including the default window size. Since a Web card needs only display a URL, the default shape leaves most of the text area blank.

To make Web cards better fit the text area and visually differentiate them from cards of other types I reduced the default height to slighly less than half. The text of a Web card now has enough vertical space for three lines of a wrapped URL. The change makes Web cards closer to badges or tags with a URL as a label than a textual note.

To see the result compare the Web card at the top with the Text card a the bottom:

I made other changes to WebCard, some of which related to the new card shape. First, the WCD.UpdateCardText function now scrolls the card window back to the top to ensure the initial portion of the URL is always in view.

Next, I modified WCD.ValidURLP to check that the lenght of the input URL doesn't exceed 255 characters, the maximum a card property can hold.

Finally, I completed the initialization of Web cards in WCD.MakeWebCard to handle cards that are not immediately displayed upon creation. This is the case of a Web card created via the NoteCards API when the nodisplayflg parameter of NCP.CreateCard is non NIL, instead of interactively by the user. I factored out the code common to displayed and undisplayed cards into the separate function WCD.InitCard.

It took me longer than expected to understand the initialization flow of undisplayed cards. My early attempts produced errors about a missing TEdit window as I unknowingly skipped the initialization of the parent Text type. Calling the parent constructor resolved the issue.

#WebCard #Interlisp #Lisp

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I fixed a URL validation bug of WebCard I have been stuck with for almost a week.

When creating a new card, the function WCD.AskURL brings up a dialog and loops prompting for a URL to go with the card until the input is valid. After the fix the input dialog looks like this, here shown above a new blank card. I entered https, the dialog warned it's not a valid URL, and then I typed a correct one.

WCD.AskURL initially checked only for a null input. I later wrote WCD.ValidURLP to check that the input resembles a URL.

In an attempt to call WCD.ValidURLP from the WCD.AskURL input loop I bumped into a syntax error in the bind clause of an Interlisp iterative statement. The issue eluded me when staring at the code for long. Then the problem suddenly jumped at me: a missing ← symbol.

The bug is now fixed for good and I can move on.

#WebCard #Interlisp #Lisp

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The text of WebCard cards is intended to be read only but my previous attempt to achieve it by overriding card editing didn't work. I implemented a new, simpler approach that actually works.

The card type Web inherits from the Text type whose “substance” is a text stream associated with the TEdit editor embedded in Text cards. In NoteCards a substance is a data structure that contains the information in the card.

The trick of the new approach is to just make the text stream of the card read only.

An additional complication is that the read only state is a runtime property of open streams not preserved in saved notefiles. Therefore, if in a new session you load a notefile, any previously read only cards it stores will no longer be so. To catch this WebCard now intercepts the first access to an unopened Web card, which occurs when clicking a link icon to the card. I modified WCD.TraverseWebLink to set the text to read only.

If the user clicks the text area of a Web card and starts typing, a dialog informs that the text is read only. The Close option of the right-click menu dismisses the dialog.

A number of WebCard functions display the URL of a Web card in its text area. Since the code for inserting the text and handling the modification state was scattered and partially duplicated in various places, I factored it out into the new function WCD.UpdateCardText. It sets the card text to read-write, clears the existing text, inserts the new text, and makes the text read only again.

#WebCard #Interlisp #Lisp

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A URL is associated with a WebCard card of type Web at creation time but it may later be necessary to change or take action on the URL. For example, to correct a typo or visit the URL again if its web browser tab was closed since an earlier visit.

For such situations I added the items Visit URL and Edit URL to the title bar menu of Web cards. This is the menu:

The card holds the URL shown in the text area. Left-clicking on the title bar brings up the menu with the new items Visit URL and Edit URL at the top.

The NoteCards API function NCP.AddTitleBarMenuItemsToType adds items to the menu of a specified card type. It's easy to use but it wasn't clear to me what arguments the item callback functions are supposed to take. Some experimentation with throwaway code revealed the system passes only one argument to callbacks, a window.

To prepare for the new functionality I factored out the initialization of the Web card type into the function WCD.InitWebCard that also calls NCP.AddTitleBarMenuItemsToType.

Functions WCD.VisitURLMenuCmd and WCD.EditURLMenuCmd carry out the actual menu actions and are straightfoward. In addition to updating the URL property of the card, WCD.EditURLMenuCmd substitutes the new URL for the old in the text area.

#WebCard #Interlisp #Lisp

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The WebCard project is moving forward again. My latest work involved card initialization and URL visiting.

When a new Web card is created, the associated URL is now inserted as text in the content area of the card. This is useful documentation and prevents the potential confusion of a blank card.

Speaking of card initialization, the WCD.AskURL function that prompts for a URL initially prefilled the input buffer with https:// to spare some typing. But testing revealed an unexpected behavior of NCP.AskUser, the NoteCards API function URL prompting is built upon.

As soon as the user starts typing, NCP.AskUser deletes the prefix https://, whereas I assumed the new text would be appended to https://. To avoid the confusion WCD.AskURL no longer prefills the input buffer unless the function is called with an optional prefix. Even if deleted when the user types, the current URL will serve as an initial reminder when editing a card URL.

Finally, I factored out the code that visits a URL into its own function WCD.VisitURL since I'll eventually revise the feature and call it in other contexts.

#WebCard #Interlisp #Lisp

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This is the year of my Linux desktop.

Three months ago today I moved back to Linux for good after almost a decade with ChromeOS. That day I installed Linux Mint Cinnamon on a freshly delivered System76 Merkaat.

I was growing increasingly dissatisfied with ChromeOS and bumping into the restricted confines of its Crostini Linux container more and more. The last straw was the rumor of Google considering a Recall-like feature for ChromeOS. I didn't like Chromebook Plus fragmenting the platform by delivering exclusive features only to premium users, either.

I put together my requirements for a Linux PC and distro and finally went with the System76 Merkaat and Mint.

Prior to the switch to ChromeOS I had been using Linux for almost two decades and coming back to Linux felt incredibly good. But I was still unsure and concerned about the hardware compatibility and stability of Linux.

Mint immedially dispelled my compatibility concerns as it fully supports every single hardware feature of the Merkaat and the connected peripherals. Nearly no software configuration is required, and the little that is is as simple as installing a couple of packages with the system's package manager.

As for stability, an incorrectly flashed USB boot stick caused some Linux installation glitches. A borked upgrade from Mint 21.3 to 22 forced a full instsllation of Mint 22. And I managed to lock myself out of my account, forcing another full reinstall.

The bottom line is I practiced enough emergency reinstalls I now have the experience to complete the full process in under three hours.

Despite the initial setbacks and annoyances, some of which due to my rustiness with Linux, it has been smooth sailing over the past three months. And the flawless software updates grew my confidence in Linux and my setup.

#Linux #ChromeOS

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I started working on URL validation in WebCard and soon bumped into a bug.

When creating a new Web card, WebCard prompts for a URL to store in the card. I wrote the predicate WCD.ValidURLP to do some minimal validation and make sure the input resembles a URL. For example, the function checks whether the input starts with https://, http://, or mailto:. Although I don't want to write a URL parser I ended up adding more logic than anticipated.

I could skip URL validation altogether and defer error cheking and reporting to the web browser. Or allow URLs with no URL scheme such as interlisp.org that a browser can handle. But it's probably better to have full URLs as a form of card documentation.

Next I tried calling WCD.ValidURLP from WCD.AskURL, the function that prompts for a URL in a loop until the input is valid. An Interlisp iterative statement with a bind clause controls the loop.

But I'm getting syntax errors for bind in the statement. I checked the documentation, read sample code, and tested a few variations.

I'm still struggling with this.

#WebCard #Interlisp #Lisp

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I wrote some throwaway code to experiment with editing cards of type Web in WebCard, my RetroChallenge 2024 project. The goal is to make the card read only with the least amount of effort.

In a NoteCards hypertext a Web card is a stand-in for a website, a placeholder for a URL that gets visited when links leading to the card are clicked. The Web card type inherits from the Text type but, since the user isn't supposed to enter text into a Web card, the card should be read only.

An approach I tried is to override the card editing operation for the Web type. The overridden function was a no-op that did nothing and immediately returned, as I thought not calling the TEdit editor would prevent text from being entered or modified.

It turned out the function worked even too well and did nothing at all, really. Like, not even opening or displaying the card.

Back to the drawing board.

A more substantial function would involve additional complexity to interact with TEdit, which would do nothing anyway. An easier approach is to make the content of a Web card read only in the constructor as soon as it's created.

I'm actually also considering to drop the read only requirement and allow editing the content of Web cards. It could be handy to enter a description or note about the website.

#WebCard #Interlisp #Lisp

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Success!

My WebCard prototype made NoteCards visit a site on the World-Wide Web for the first time. Think of it as a wormhole that connects the old world of hypertext with the new world of the modern web. WebCard, a NoteCards extension for visiting websites, is my RetroChallenge 2024 project.

This is my Linux desktop just after NoteCards visited a website for the very first time:

The Table of Contents window near the bottom left of the screen is a filebox of a NoteCards hypertext. Under “NOTE CARDS” the filebox container card lists a link icon, a clickable area that leads to the indicated card “Medley Interlisp Project”. This card of type Web inherits from the type Text and holds a URL to visit.

When I clicked on “Medley Interlisp Project”, WebCard opened the corresponding card — blank in the screenshot — next to the Table of Contents. Then WebCard commanded Firefox to visit the URL https://interlisp.org stored in the card. The window of Firefox, already running, came to the foreground and displayed the website in a new tab.

This milestone comes after fixing a bug in the Web card constructor. To put my core idea to the test I deferred some non essential refinements and went straight for the website visiting functionality.

How does the functionality work? The NoteCards API provides a hook to override the operation of traversing links to specific types of card. To this effect WebCard sets an alternate function as the value of the LinkIconLeftButtonFn property of the symbol Web that names the type. NoteCards calls the alternate function when a clicked link has a Web card as the destination.

WebCard's alternate function is WCD.TraverseWebLink. It fetches the URL from a card, displays the card, and opens the URL in the system browser.

The screenshot shows both the Web card, next to the Table of Contents, and the code of WCD.TraverseWebLink in the Lisp editor at the top center. The comment, however, is out of date after fixing a series of issues.

What went wrong? A combination of misunderstandings and incomplete information made WebCard generate argument type errors, as I wasn't sure about the arguments of WCD.TraverseWebLink. On top of this, I called the internal function NC.TraverseLink that implements the default link traversal but I ended up not needing anyway.

Reading the sources of a few NoteCards functions cleared all doubts. To fix the issues I updated the code of WCD.TraverseWebLink but not the comment as I was eager for a test run.

The WebCard prototype is crude, but it works and validats my strategy of overriding the link traversal behavior.

An alternative I initially considered is to advise the NoteCards API functions for opening and displaying cards. However, unlike overriding link traversal which the API fully supports, advising is a fragile kludge that works around the API.

Now that the core feature of WebCard is in place I can continue the development.

WebCard is far from complete. There's still work to do to override editing Web cards, extend Web card construction, deal with input validation and error handling, check for visited URLs, and customize the bitmap of Web link icons. WebCard needs documentation and demo notefiles too.

#WebCard #Interlisp #Lisp

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