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Construct a legitimate variable from a string?


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I tried to looking into this quite a while ago and didn't really get anywhere. Again, I find myself needing to do this and am taking another stab at it. I've done some searching and can't find a way to get this to work. What I need to do is be able to construct a string that matches the name of a variable and then have the script I'm writing return the value of that variable using the constructed string. Below is an example:

$Test6_Time = 86

$identifier = 6
$string = "$Test" & $identifier & "_Time"
ConsoleWrite( "This is the actual variable: " & $Test6_Time & @CRLF & "This is the constructed variable: " & Eval($string) & @CRLF )

I thought that Eval() might do the trick but I obviously don't understand quite how Eval() works as it fails silently.

Can anyone provide some help with this?

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$Test6_Time = 86

$identifier = 6
$string = "Test" & $identifier & "_Time"
ConsoleWrite( "This is the actual variable: " & $Test6_Time & @CRLF & "This is the constructed variable: " & Eval($string) & @CRLF )

Console

This is the actual variable: 86
This is the constructed variable: 86

 

Let's see if you can spot the difference.  :)  If not, click on "Reveal hidden contents".

Spoiler

When using Eval, the string that makes up the variable name should not include the "$".

 

Edited by TheXman
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And kicking myself. In fleshing out some of my code I just made ANOTHER error in omitting an "$" where there should have been one. At least I was the one who caught it this time.

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8 minutes ago, Bagel said:

I just made ANOTHER error in omitting an "$" where there should have been one.

Actually, the problem this time was the exact opposite.  You added a "$" where one should not have been.

$string = "$Test" & $identifier & "_Time"

Should have been 

$string = "Test" & $identifier & "_Time"

 

Edited by TheXman
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Posted (edited)

Yep, apparently I have some sort of subconscious issue that's crossing my wires when the "$" is involved. Not sure the forums can help me with that. Actually, I think this time it was a conceptual issue regarding variables. It's ingrained in me that variables MUST begin with a "$" and I think that led me to make an implicit assumption about what Eval() was doing. Conceptually, Eval() and Assign() etc. are a bit abstract to me. Thanks again for the help!

Edited by Bagel
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4 hours ago, Bagel said:

Yep, apparently I have some sort of subconscious issue that's crossing my wires when the "$" is involved.

Perhaps the crossed wires come from the differing requirements of the sister functions Eval and Execute, as shown here:

Eval:

Local $iA = Eval("iB")

Execute:

Local $iA = Execute("$iB + 1")

To my mind, Eval should be called Recall() (to go with Assign()), and Execute should be renamed Eval() cuz thats what it does.

Code hard, but don’t hard code...

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And both functions should only be used in extremely rare, very specific situations.

IMHO: never in regular code.

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SQL tutorial (covers "generic" SQL, but most of it applies to SQLite as well)
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SQLite official website with full documentation (may be newer than the SQLite library that comes standard with AutoIt)

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