What constitutes "declaring a variable" is difficult to define because
the minute
I type:
put "Graham" into SAMUEL, the variable SAMUEL "pops into existence", and
it could be argued that the first mention of a variable constitutes its
declaration.
And if that is what constitutes "declaring a variable" I could hardly
claim "I've never declared a variable in Runtime Revolution".
However, I understand "declaring a variable" to mean an
explicit declaration (without assigning a value) at the start of a block
of code.
And, I have never done that in Runtime Revolution, not, for that matter, in
BBC BASIC . . . :)
Did it until I was blue in the face way back with MiniFortran (OUCH!),
Fortran 4
and PASCAL 5; thought I'd never see the likes of it again.
-----------------------------------------------------------------------------------------------------
Section follows where Richmond puts a baited hook into the Use-List
-----------------------------------------------------------------------------------------------------
Hey, when is Runtime Revolution going to go Open Source?
----------------------------------------------------------------------------------------------------
well, you know, wouldn't want to disappoint Kay C Lan now would we ?
----------------------------------------------------------------------------------------------------
However (getting back on topic with an extreme effort of will), when I have
developed software for others than myself I have done this sort of thing:
on mouseUp
put fld "fENTRY" into VALWUN
-- VALWUN is the seed that the end-user entered into the field "fENTRY"
-- the seed can now be run through the algorithm
end mouseUp
while this is not declaring variable it is, at least, giving some
explanation of
what the variable is/contains and/or what it is used for.
As I pointed out in an earlier post, one can do one's own bl**dy-minded
thing
with Runtime Revolution far more than with many other programming suites;
this, of course, can have 2 sides:
1. You can program away in a style that suits your way of thinking and
organisation.
2. It can make other people, who don't share your way of thinking and
organisation
find things hard going when they want to understand your code.
Obviously one of the ways to minimise this is by explicit declaration of
variables,
another way is by extensive annotation within the body of the code, as
per my
example above.
Graham Samuel wrote:
I think all this proves that different people can and do use
Revolution / xTalk differently. Personally I am persuaded by Jim's
argument, and indeed I have changed: when I first came to xTalk after
years of using languages where declaration of variables was mandatory,
I relished the freedom of not having to do so. But gradually I got
tired of debugging my own spelling mistakes and moved over. However I
have enormous respect for the Jacque and Richmond, who are clearly
highly productive NOT using Strict Compilation, so I'm glad there are
the two ways of doing it...
BTW I can't quite follow Richmond when he says
Funny, I've never declared a variable in Runtime Revolution
Do you never carry values from stack to stack or handler to handler
via globals? Maybe you always use custom props. But AFAIK, when you
write:
put "Richmond" into myGlobal
in a handler without a corresponding 'global' declaration, and then in
another one in a different galaxy, far away, you write:
put myGlobal
you won't see "Richmond" in the message box, will you?
As an aside, I noticed that if I start a repeat statement with
something like:
repeat with i = 1 to 20
even with ExplicitVars on, the local variable "i" does not have to be
declared. I could not find an explanation of this in the docs, but
perhaps I didn't look hard enough. I admit I find this useful, but
then I am a convert as explained.
Graham
On Sat, 9 May 2009 13:56:11 -1000, u "Jim Bufalini"
<[email protected]> wrote:
Richmond Mathewson wrote:
May be this is a goofy question; but it can probably bear
the asking one more time:
What, if any, is the advantage of declaring variables in RR ?
- Unles yu ar an perfct typst who has nevr made a typo and nevar use
a speel
checker, explicitVariables instantly indicates a speling eror at
compile tim
and alows you too quikly corect.
- This is also very helpful to people to whom English is a second
language
and English spelling is not intuitive and they can and often do put
one r
or l in one place and two r's or ll's in another and other such typical
English spelling errors.
- It allows you to distinguish globals from script locals and
constants both
at the script level and handler level.
- It allows you to declare globals from inside a handler (which
creates a
"semi" global that is only available to other handlers that also
declare the
same global).
- It makes your code much more readable, not only to others, but to
yourself, when you are troubleshooting a problem weeks or months or
years
later.
- It is "polite" to others with whom you may want to share your code and
they have explicitVariables turned on. They are not going to turn it
off for
a large project just to look at few lines of your code.
- If you use GLX2, it allows GLX2 to offer you variable completion after
typing four chars of a declared variable name.
- The reason the name was changed is probably because it also checks
that
you have not spelled reserved words incorrectly. *set the locaton of
this
stack to screnLoc* will not give a compile time error if Strict
Compilation
Mode is turned off. If it is on, you get an error. If you are just
learning
the language, this is big help.
Lastly, although you can "create" variables without declaration, the
fact
is, variables cannot be created on-the-fly at runtime. Only array
variables
and custom property variables can be created on-the-fly. Otherwise,
you must
use a *do* statement, which has limitations, is slow because it is
complied
at runtime and can be tedious and error prone to write a long one. All
other variables are whatever you typed on compile.
So, given these facts, the real question is:
What, if any, is the advantage of NOT declaring variables? ;-)
Aloha from Hawaii,
Jim Bufalini
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