Both definitions use the term "specific instance", or similar. That is what confuses me.
Variables with names that start with “Local ” or a double-struck L (𝕃) are considered local to a specific instance of a specific macro. Each time the macro is run, they will start empty and no other macro will see or be able to change values.
Variables with names that start with “Instance ” or a double-struck I (𝕀) are considered local to a specific execution sequence. Each time the macro is run, they will start empty but their value can be seen and changed by other macros within the same execution sequence (for example, if you execute a macro using the Execute Macro action, that macro can see and change the instance variable). Since two instances of a macro can be running at the same time, this is useful to ensure they each have their own version of the variable.
Yes, the Prompt For User Input currently can't set the local/instance variables because essentially it's running in its own instance. I can work around it I think, but it wont happen in 8.0.1.
Also, as stated elsewhere, I am going to remove the double-struct I and L (𝕀 and 𝕃). The characters cause problems because they are not even in the first unicode plane.
If people have suggestions for alternative characters, I am open to adding a different alternative.
The difference between Local and Instance is whether the variable is strictly limited to the macro it is in (Local), or is limited to the macro execution instance it is in.
The difference becomes apparent when you call a sub-macro. The sub-macro is in the same execution instance, so it can see (and set) Instance variables. But it cannot see Local variables.
Other similar black/white pairings like circles, squares
Otherwise, chars that are in the BMP and also part of the standard US keyboard layout:
The quote marks: › Instance, » Local
Simply: > Instance, >> Local (might cause parsing problems?)
The dagger: † Instance, †† Local
Exclamation marks: ¡ Instance, ! Local
Semantics/semiotics:
The doubling as well as the white/black pairing has a semantic logic, since Local is more restricted than Instance (right?). The exclamation mark can be seen as resembling to the letter "i", as well as a warning that the variable is not accessible from outside of the macro (e.g. from embedded AppleScripts).
I'm not a friend of arbitrary chars like æ and Æ, because these are actually letters (not symbols) and the letters they are are not related to the initial letters of the subject (I and L).
Furthermore the different height of the glyphs makes for an ugly, unbalanced appearance, and we have to live with this decision for a long time
The only esthetically (halfway) pleasing and semantically meaningful Letterlike on the standard layout I could find is the Pound-L: £ Instance, ££ Local
Here a visual representation:
My favorites are the exclamation marks ¡ and !, and to some degree, the Angle Quotation Marks › and ».
Each of them can be typed with a single keystroke and they are somewhat meaningful, the ¡! more than the ›».
Edit: An afterthought:
The more I think about the proposed ¡! solution the better it appears to me!
Some facts:
Extremely easy to type: ! is Shift-1, ¡ is Option-1
The semantics are OK:
¡ resembles perfectly an i like in "Instance"
!, well, with a bit of imagination you can se it as lowercase l with a dot below
Both characters have the semantics of a warning: ‘you can’t access the variables from a script or from the shell!’
The pragmatics are perfect:
Local variables will be used way more often than Instance variables. And the sign for the local variable (!) is even printed on the keyboard (= easiest access possible)
The (less used) Instance variable sign (¡) is not printed on the keyboard but it doesn’t require any more keystrokes either.
Both are single-figure signs, that is they don’t lengthen the variable names like the proposed double signs do.
The esthetics are perfect too:
Since KM Editor is using a proportional font, the ! as well as the ¡ are really thin, that is, non-obtrusive.
In fact, the ¡! solution seems so good to me, that I’m almost sure that there is something in the way that prevented Peter from choosing it right from the start (referring to the KM8 update). Maybe a parsing problem in the context of calculations?
BTW, I wouldn’t care about the contradiction to the usual semantics of the ! as ‘not’. It is clear in the context that this is not an operator but just a Sigil.
The underplaying problem of all that is that KM’s variables are global and persistent by default.
KM variables should have been always, IMO, macro-local by default, with an option to create global/persistent variables when needed. But, as far as I know, Peter is not the original author of the program, and, of course changing this now would break a considerable part of all existing macros. So we have to live with that.
In future macros (if handled correctly by the author) the majority of variables will be local, and that’s why I think it is really important to find a decent, non-obtrusive solution.
And, by the way, you can’t use local variables in shell or AppleScripts, since they are limited to the macro. (They are not in the ENV, unless I’m missing something.)
I also was unsure, but I tried it in my first KM8 macro, and accessing local variables from the contained AppleScript didn’t work. (getvariable)
I didn’t try it with shell scripts though.
And it seems logic, since they are stored nowhere (“local”). However, it would be indeed great if we were able to access those variables from scripts that are launched by the macro itself (i.e. embedded AppleScripts or shell scripts). But I guess this would be a really major complication.
So, since using a Execute Macro is in the same execution instance, shouldn't Execute Script be as well, and thus, instance variables should be available to scripts?
@Tom, thanks for your thoughtful and comprehensive discussion.
I am good with your preference of ! and ¡.
The logic is good, keyboard access is good, and the memory association of ! with l for local, and ¡ with i for instance, works for me.
The only drawback is that using these does NOT allow you to quickly select the entire variable name by double-clicking -- it does NOT include the exclamation marks. I need to do this a lot. For example, setting a variable in one action, and then using it in the next, or later, action.
Since you tried two characters, I have done the same, just for comparision:
!SomeLocalName
¡SomeInstanceName
llSomeLocalVarName
iiSomeInstanceVarName
LLSomeLocalVarName
IISomeInstanceVarName
Visually, I still prefer the exclamation marks.
So, @peternlewis, I can support @Tom's suggestion of exclamation marks.
Now that understand "local" vs "instance" variables, it seems to me (per my post to Peter above) that instance variables should be accessible to scripts.
But instance variables are NOT available to scripts, at least not to AppleScript. Here my test macro/script:
The !¡ escape from double-clicking because they are punctuation (they are word-breaking). Of course the same is true for ›» and also for £. 𝕀 and 𝕃 are working fine in that respect.
However, as you also have stated, I don't think that this is game breaker. But, maybe somebody comes up with a better solution.
As a sidenote, I was quite content with @peternlewis' initial choice (𝕀 and 𝕃). OK, you might need a snippet expander to insert them, but, since we all have KM this shouldn't be a problem. But I'm interested to know why he thinks that the fact that those chars are not on Unicode Plane 0 (BMT) poses a problem.