[Coco] What are the rules for naming basic09 variables ?

[Wayne Campbell]

Ok. That makes sense. As for the symbol table, in packed i-code, it is a
list of 3-byte entries. The first byte is the variable type, and the
integer is the memory offset where that variable's contents are stored.
This is the simple description. It is more involved when you get into it.
The cocopedia page I created has all the info on what the various values
are.

On Sat, Jul 27, 2019, 7:58 PM James Jones <jejones3141 at gmail.com> wrote:

> The relevant code starts, I believe, at L2430 in basic09_6809.listing. It
> accepts a letter followed by some number of alphanumerics or underscores,
> optionally with a $ at the end as the string sigil. The loop doesn't itself
> bound the length of the variable name, though there's also the matter of
> the size of the buffer used to read lines of source code, which would also
> bound the maximum variable name length. Further down, though, is
>
> L2459  stb <NAMELEN    Save size of variable name
>
> so that a variable name length greater than 255 won't fit in the B register
> and the wrong value will be stored in <NAMELEN.
>
> The other thing that may bound the length of a variable name is: what does
> the symbol table look like? The first time you see a variable or parameter
> mentioned, you have to save its name; the lexical scanner code is looking
> through a buffer that I suspect only exists while you're loading or editing
> a source file. Depending on how the symbol table is set up, it might have a
> fixed limit on variable name length. (I haven't gone looking for the symbol
> table yet.)
>
> That said--all that really matters is:
>
>    - The maximum length, if it exists, is considerably greater than two, so
>    in BASIC09 you can have intelligible variable names without coming
> anywhere
>    close to the maximum length, if it exists..
>    - Variable names don't appear in I-code as such, so executing BASIC09
>    code doesn't involve looking up variable names, and as others have
> pointed
>    out, they don't take up space in packed I-code modules.
>    - You'll notice that a variable or parameter name will always show up in
>    a listing with the case you used the first time BASIC09 saw it. This, I
>    believe, implies that BASIC09 only keeps one copy of each variable or
>    parameter name (the one in the symbol table) around, so even in BASIC09,
>    the space overhead of variable names is minimized. Also, IMHO, it tilts
> the
>    balance towards using camelCase rather than snake_case. Type names the
> way
>    you want them the first time, and thereafter you needn't hit the shift
> key.
>    BASIC09 will do the work for you, and you don't have underscores taking
> up
>    room.
>
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