Hi, what is the meaning of the TDBISAMEngine component?

As far as i know i can access the current application engine properties with
something like that in the application project file:

with Engine do begin
active:=false;
<modifications>
active:=true;
end;

and from this point ahead, all the data operations will use that modified
engine. Is this correct ?

So, do i actually need to put a TDBISAMEngine component (for instance) in
the datamodule, to change its properties?

Maybe the component is designed so you can put more than one engine in the
app, and activate one or another one, to access these or those files?

In this case, every operation on databases and tables use the currently
active engine, right?

Thanks for any clarification.

Alessandra

>Hi, what is the meaning of the TDBISAMEngine component?
>
>As far as i know i can access the current application engine properties with
>something like that in the application project file:
>
>with Engine do begin
> active:=false;
> <modifications>
> active:=true;
>end;
>
>and from this point ahead, all the data operations will use that modified
>engine. Is this correct ?

Correct.

>So, do i actually need to put a TDBISAMEngine component (for instance) in
>the datamodule, to change its properties?

No. Only if you want to change the properties in the IDE rather than at run time.

>Maybe the component is designed so you can put more than one engine in the
>app, and activate one or another one, to access these or those files?

NO! As you found if you don't drop a TDBISAMEngine into your app one will be created for you, but its a singleton. Dropping two on WILL cause problems.

>In this case, every operation on databases and tables use the currently
>active engine, right?

Yes

Roy Lambert [Team Elevate]

Thanks a lot Roy, everything is clear now, after your answer.

Just add to Roy's comment that i personally like to place the engine
component in apps if i use any engine events - triggers, functions,
login/logout, etc

They can be wired in code agaisnt default engine but i find it easier to
just look at events tab on Engine component to see which ones we're using on
specific app and then double-click takes me to it. Small convenience but
handy.

Raul

"Roy Lambert" <roy.lambert@skynet.co.uk> wrote in message
news:EFB4D247-A36F-43C3-B243-4423991304E3@news.elevatesoft.com...
>>So, do i actually need to put a TDBISAMEngine component (for instance) in
>>the datamodule, to change its properties?
>
> No. Only if you want to change the properties in the IDE rather than at
> run time.