Okay, I get it now. Nice little essay, Jacque!
Many thanks to Jacque and others on this thread.
Tim
On Jun 19, 2011, at 8:48 PM, J. Landman Gay wrote:
> On 6/19/11 4:10 PM, Timothy Miller wrote:
>
>> Is it true that the "do" command and the "value" function perform
>> about the same tasks in different ways? I.e., is it true that you can
>> avoid "do" by judicious use of "value"?
>
> They are for different purposes and not really interchangeable. The value
> function is more limited than "do", it just returns a single evaluation of an
> expression. "Do" can execute a whole script at a time, but it has a lot of
> overhead and should be avoided when possible.
>
> I have never needed to nest value() functions, as per your other post; there
> is almost always a better way. The example of value(value(line x of fld y))
> is redundant; just "get line x of fld y" is enough to give you the text of
> the line. Most things you want to do are like that, there are usually
> alternatives.
>
> You need value() occasionally to force an evaluation when there is no other
> way. For example, it is used to call a function remotely when the function
> isn't in the message path:
>
> put value("myFunction()",stack "mySubstack")
>
> In many cases you don't need value() at all, just supplying parentheses will
> force an evaluation. Parentheses are required for that reason when getting
> the contents of a URL container:
>
> get url ("file:"& fileVarPath)
>
> Without the parentheses the call will fail. The text must be evaluated into a
> functional URL before it can work, and the parentheses force that to happen.
>
> A common purpose for "do", besides constructing variables or syntax on the
> fly, is to execute commands in another language:
>
> do field 1 as applescript
>
> That will force the AppleScript compiler to load. If you are "do"ing
> something in LiveCode instead of applescript, then LiveCode's own compiler
> needs to load. A "do" is functionally similar to opening the script editor,
> typing some commands, and hitting the "compile" button.
>
> There are so many built-in ways to get values that explicitly calling "do"
> (or value) isn't necessary very often, though sometimes there is no way
> around it. If you want to post a few of your own "do" examples, maybe we can
> see if there is a different way to execute them.
>
> --
> Jacqueline Landman Gay | jac...@hyperactivesw.com
> HyperActive Software | http://www.hyperactivesw.com
>
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