025 // Distractions III: External Random Item Drop Generator
So you may be wondering what happened to last week's post, and the answer is that I never wrote it because I was too busy trying to finish this side project I have been working on. And I finished it!
I think I might have offered to explain it a while ago, so I will do that now, since I have very little new art to offer at the moment (it is probably not why you are here but please bear with me).
This one is a bit long and is all about code..
For the last few weeks, I have been working on an external random item dropper for a couple of friends who want to start their own thing, and doing that required me to either construct an entire user interface arrangement in Pygame (which I have done twice already and have my own modules for but am not really super-de-duper into) or to learn at least enough Tkinter to make something I am not totally ashamed of (which is a lot of learning because I know-- which is to say, knew-- almost exactly nothing about Tkinter, not counting some stuff with Listboxes.
I opted for the latter and, in truth, it was pretty easy to learn. It was a bit frustrating at times because there are problems with Tkinter's 'widgets' (graphic interface objects) that can occur and lock up the software in a way that Tkinter considers normal and not an error and why would it tell you about it? For instance, if you try to use a "grid" arrangement in the same Frame (an object Tkinter uses to create layers of widget organization) as a "pack" arrangement, it will "Tkinter will happily spend the rest of your lifetime trying to negotiate a solution that both managers are happy with," or how replacing Variable objects with new ones that have the same name sometimes causes the whole affair to silently stop working and leave you clicking a button to no effect, wondering what is going on and why.
Problems which I overcame! Quickly and with some difficulty! Most of my time was spent on the interface, actually, since it was the part I knew the least about. The design was pretty easy (or it was easy in the extent that I produced an interface experience that I, personally, found satisfying, and which failed to produce a/any complaint(s) from the people for whom I made it) but the actual construction took a lot of learning when it came to displaying and updating the right variables in the right places and when. There are many values shared between user input boxes (Tk.Entry), where the user enters various bits of data, lists (Tk.Listbox), which have selectable entries and a lot of straight-forward appearance parameters, labels (Tk.Label), which display values either as static text or from various types of Variable, and, of course, the item data sheet that the user provides (read using ConfigParser from an simple external text document I can tell you how to make, and internally, as a chaotic dictionary of lists and Variables and strings and numbers). Incidentally, I ended up extending (adding my own functions and attributes to) a few of Tkinter's basic classes, and this part of the project was actually one of the most interesting. A great many parts of the original module have been deliberately constructed in a way that simplifies that kind of extension, and while I had to go outside of that on an occasion or two, it was absolutely a worthwhile lesson!
The Variables were the most perplexing part, because Tkinter is the least forthright about them and because they are more flexible than they let on. These variables can be equipped with callback functions that allow them to alter their contents, or the contents of other widgets, or do some other crazy third thing, whenever they are altered, or even just whenever something looks at their values. That part was easy and extremely useful once I got the hang of it! They can also be given specific names by which other functions and widgets may identify them, and while I found this quite useful as well, its lack of stability was somewhat less endearing since Tkinter will not tolerate two variables with the same name (a legitimate and preventable issue!) and will not necessarily tell you when this has happened or where (I am less okay with this).
Another interesting thing about Tkinter is that it offers multiple obvious ways of accomplishing the same thing, which is a bit of a problem for "The Zen of Python," a sort of mantra that a lot of people in the community take quite seriously. As an example, you may almost always alter the configuration of a widget in at least two ways: - Use Widget.config(some_attr = value) and change one or several attributes at once using arguments, or - Setting them using attribute names as keys, like so: Widget['some_attr'] = value. - There are other ways too but none spring to mind.
Also, widgets can be stored in attributes, but you can also call them up using their names: a widget created in the line
myObject.my_widj = Label(master=tk_root, text='Yo, babe(l), I am a Label!', name='lbl_annoyinglabel')
..can be accessed directly either by way of some object attribute reference:
myObject.my_widj.config(text = "Hey, id'jit, I'm a widget!")
..which is absolutely normal in Python, or by calling it by name from its master object:
tk_root.nametowidget('lbl_annoyinglabel')['text'] = 'Please stop talking.'.
Naturally, you would probably want to use the first method as often as possible, because it involves fewer operations and would probably be easier to maintain. But the second way, more elaborate though it may be, lets you save on assigning attributes by tracking widgets using Tcl's internal structure. (n.b.: I cannot say I have ever found myself running out of room for attributes in a namespace but I am also a complete amateur as a programmer so please bear with me. <3 )
Interestingly, actual structure of the input sheets was the next-most time-consuming part. Trying to find a data format that would be easily comprehensible by anyone who picked it up (probably only going to be two people, plus myself, if even that many) and which also met with ConfigParser's profoundly elusive approval was a somewhat complex task. It turned out to be exactly as hard as I thought it would be, at least, and there were no surprises here. You can see a blank template of the input sheet here!
The actual drop generator code-- the element which takes the user-supplied data and returns a random selection of items from it, according to their initial and supplemental parameters; the single element that the entire program is built to support-- only took an hour to complete, actually. I did it last and by then, all of the parameters and variables and their names and locations had become obvious, and since it was a pretty plain function to start with, it was done quickly. It was interesting to note how much more effort it was to pack this simple function up into a pretty interface than it took to build the core element itself. I suppose we see this everywhere: a car is just self-propelled chairs; a human is just a gangly, leaky chariot for a suite of genitalia; this software is just 'arbitrary decisions' packed in a pretty box. A very pretty box that I will no doubt look back on in two years and wonder what I was thinking, I hope!~ <3
Anyway I completed it and delivered it and it is my first free-standing piece of software that some other person might actually use for their purposes, and that is a sense of accomplishment I have not felt since the WSDOT departmental library people told me they wanted to include my undergraduate thesis in their stacks.
As an aside, I had considered making a companion tool to go with the drop generator that simplified drop sheet creation. It would not be over-hard to make: all it is liable to be is another Listbox with a text entry field attached, a button or two to add and remove entries, a few other configurables, and a ConfigParser set up to save it all out, but I feel as though the drop sheet format-- sensitive as it is to typographical problems and formatting issues-- is probably easy enough to use. Also there are two people using it and I am in touch with one of them almost every day. Still, food for future thought!
Anyway, back to my game, now! It has been a long time and I am ready to face it again with fresh eyes and fewer .. days.. to live.. I guess! Hm..
See you next time! :y
