libdatabase : connection problem

[Trevor DeVore]

On Aug 28, 2005, at 6:12 PM, Dan Shafer wrote:
>> Sunday, August 28, 2005 12:45:34 PM (GMT +02:00)
>>
>> event from button :
>>
>>   local tDbA = ""
>>   local i = 0
>>   local tDataA = ""
>>
> The above lines are doing nothing for you because they are  
> incorrect syntax for Revolution. The expression "i = 0" evaluates  
> to either true or valse but does nothing with the result. IF what  
> you intend to do here is to initialize local variables, then you  
> need the slightly more verbose:
>
> local tDbA
> put empty into tDbA (or you can use double quotes instead of "empty")
> local i
> put 0 into i
> local tDataA
> put empty into tDataA

Dan,

Declaring a variable as local initializes to an empty variable. So -

local tDbA,tDataA

would initialize both variables as empty.  For example:

on doSomething
     local tVar

     put tVar &cr& tVar2
end doSomething

Would display and empty line, a return and "tVar2" on the second line  
in the message box.  You can initialize a variable to value as well.

on doSomething
     local i = 0

     put i
end doSomething

would print 0 in the message box.

> Having said that, it is strictly optional in Transcript to use the  
> word "local" and I'd venture to say that the vast majority of us  
> never use it. Variables are local unless they're explicitly defined  
> to be global. In that case, you eliminate the three "local" lines  
> in the above and just assign the initialization values to the  
> variables with the same effect.

The person probably got the code from original libDatabase example  
code.  Back in the day I used to initialize variables with "" before  
I knew that just declaring them set them to empty.    Now I just  
define all local variables en mass:

local tVar1,tVar2
local tDataA,tWhateverA

For integers, such as i, I used to always initialize them to 0.  Now  
I only initialize them with 0 if there is a possibility of a math  
error later on in the code that could be caused by having a non- 
numeric value.

It is true that most people don't declare local variables but I do in  
all of my code.


-- 
Trevor DeVore
Blue Mango Multimedia
trevor at mangomultimedia.com