[Iv]

It would only print "1"s.

The thing is that basic programs were not entered through a 2D text-editor per rather line per line. You would type "LIST" to re-read the whole program you typed so far, with the lines in the correct order. Then, you would enter a line starting with a number. It would overwrite any existing line with the same number.

Typically, a way to correct the program you wrote would be to type:

30

15 PRINT "2"

(replace the line 30 by an empty line, and insert a line number 15)

[andyjohnson0]

Just to add that some BASIC dialects had a RENUMBER or RENUM command that would change all line numbers and references to use a consistent interval. Without that, programs could become hard to modify due to the "gaps" between the lines closing-up.

[colejohnson66]

Couldn't you just increment by 100? Or even 1000? Why did everyone use 10? Was it some interpreter limit that didn't allow line numbers above a certain amount (like 2^15 on a 16-bit CPU)?

[Klathmon]

Providex (a basic dialect that my company still uses) has a soft-ish limit of around 52000 for line numbers.

You can get around that with some flags, but its more of a pain than its worth.

We tend to go by hundreds for programs, and we have a renumber command, but using it is the nuclear option because it will break goto line number references from outside programs (yeah, that's a very common thing in this language)

[wamaral]

I'm curious, is there a specific use case for using such a language today? Is it just legacy?

[Klathmon]

Mostly legacy.

The main application is decades old, and Providex provides a database of sorts, the language/runtime, a GUI toolkit, and the ability to run on windows, linux, and as a web app (you can use a "desktop" application written in providex in the browser, a great idea in principle, but with the cost of each user license of the language becomes cost prohibitive really fast).

So while everyone agrees that providex needs to go, that would mean replacing just about every single aspect of the company's core application GUI, language, database, even simple-ish things like the editor we use (which is built into the language) all need to be replaced. It's not an easy task.

We've started moving away, but it's going to take a lot of time, and a ton of effort. Right now we are still relying on the providex db stuff pretty much across the board (although i'm launching a new node.js+postgresql server in the next month or so), and we are slowly moving our hosted applications to more traditional web languages (we have some PHP, a bunch of javascript, and a little python).

But the language hurts. It is a combination of compiled and interpreted, so unless you jump through hoops files are saved in a binary format, and you can only use their editor. This also locks us into SVN as our source control, as it's the only VCS that providex supports (and even then, it's pretty bad support). There is virtually 0 tooling, nothing is open sourced, and it's really expensive. It's impossible to remove old code as there is 0 safety, any line can be GOTO'd or GOSUB'd by any other program at any time, and while new programs don't do that, the old programs that do are the ones that you want to refactor but can't. There are also programs where we are out of line numbers and need to resort to GOSUB "hacks" to add a line.

But it's not all bad. Being able to use a "drag and drop" visual editor to make a screen that will work on windows, linux, and the web is pretty nice, and having the DB so tightly coupled means stuff like upgrades/downgrades are pretty simple and don't involve multiple systems. It's also a pretty capable language all things considered (it has classes/objects, it's not as slow as i thought it would be, and it runs on anything without any modification).

[Iv]

For a long time it was still a useful teaching language. On how many languages can you simply make two statements and have a line drawn on the screen?

SCREEN 9

LINE (100,100)-(200,200)

I only know processing that has this kind of ease of use. But any curious kid, given a BASIC interpreter and the LINE instruction will start drawing stuff around, naturally come to loops, and so on, without having to worry about the details of "real" programming languages.

[tallanvor]

Certainly, it would in part depend on the support of the interpreter, though. Realistically, incrementing by 10 was easy, and if you really needed more you could use goto to jump down and back (though obviously that's not nice for readability).

[webtechgal]

I remember there being a STEP command to set the increment value. However, when I tested it (on the PCJS sim from the top of the thread) just now, its throwing a Syntax Error!! I am nearly sure that was what the command was, but I don't know what gives right now.

[throwanem]

My BASIC memories are rusty, and more oriented toward Applesoft than Microsoft. But I remember STEP being used to give an optional increment to the FOR statement, rather than setting a line numbering increment - for example, you might

    FOR i$ FROM 1 TO 10 STEP 2
    PRINT i$
    NEXT

and get back 2, 4, 6, 8, 10, each on its own line.

I don't remember a command to set the increment for line numbers, but that may be because I never used a BASIC which didn't either require a number on every line or not care about line numbers except as targets for GOTO and similar.

[DanBC]

Which is one cause of the spaghetti:

    17 GOSUB 5500