Can two words be joined into a variable name?

[GDL Enthusiast]

Hi,

I am wondering if it is possible to change the variable name on the fly, e.g when calling from a Subroutine, having the variable name part1+part2 merged together. An example would be a variable called Var_A where the prefix is added to the suffix, like Len = "Var"+"_A".

This would be great as it would allow a single subroutine to have its parameters changed easily, from _A to _C etc, especially when there are quite a few options variables and keep the code small. Is this possible or is there a better way of making a simple repeating subroutine with different variable inputs?

For a code example in 2D Script:

option1 = 1
option2 = 1
option3 = 1

Var_A = 0.010
Var_B = 0.015
Var_C = 0.020

IF option1 = 1 THEN 
Suffix = "_A"
Len = "Var"+Suffix
Offset = 0.01
Gosub "CircleTest":
ENDIF

IF option2 = 1 THEN 
Suffix = "_B"
Len = "Var"+Suffix
Gosub "CircleTest":
ENDIF

IF option3 = 1 THEN 
Suffix = "_C"
Len = "Var"+Suffix
Gosub "CircleTest":
ENDIF

END

!*************************************
"CircleTest":              !Gosub Reference
Circle2 0,0,Len
RETURN

Ideally this should return three circles, but it comes up with an error. 

Is there a way to string together the suffix to a common prefix?

Many thanks, Matt

[Barry Kelly · Accepted solution]

No you can not change variable names, there should be no need to.

All you need in this case is ...

IF option1 = 1 THEN 
Len = 0.010
Offset = 0.01
Gosub "CircleTest":
ENDIF

IF option2 = 1 THEN 
Len = 0.015
Gosub "CircleTest":
ENDIF

IF option3 = 1 THEN 
Len = 0.020
Gosub "CircleTest":
ENDIF

I don't quite get what you are trying to do with 'option_1', 'option_2' & 'option_3' parameters, unless they are 3 separate boolean (on/off0 parameters.

So you could potentially have all 3 circles on at the same time.

If you simply want a choice of option 1, 2 or 3, then create a integer parameter called 'Option' (without the quotes) and give it a VALUES list in the parameter script.

VALUES "Options" 1, 2, 3

Then you will be able to choose only one of the circles at any one time.

Barry.

[GDL Enthusiast]

Hi Barry, 

Thank you so much for responding! I am trying to improve my coding skills. I see experts creating objects that are very concise in code, using subroutines. It seems pretty neat to be able to code so cleanly. I wondered if I could do it with changing variable names dynamically. 

That is my answer "No you can not change variable names". Thank you again Barry and all the best, Matt

[Lingwisyer]

The question is, why is there a need to change the variable name? In your example, it is redundant, hence Barry's answer. Does it not achieve what you are wanting? Is there something else you are trying to achieve?

Ling.

[GDL Enthusiast]

Hi Ling,

Thank you for responding, I have seen some of your work and you are a true GDL coding artist! It would a dream to have your and Barry's level of coding skills. 

My thought stemmed from reading AC GDL objects and how clean the script was written. I have found what would take me 50 lines of code, experts could write in 20 lines. Much neater and cleaner to follow. So my thinking became, how can I, without going back to university to get a programming degree, make my script concise and clean. Along those lines, I wondered if I could somehow reuse Subroutines multiple times, instead of writing the same repeating code but with variations in the variable names. An example of the logic being:

ValueListParameter 1 to 20, each with say 20 variables A to T. For that I code:

IF ValueListParameter1=1 THEN
Len_ = 0.2
Ht_=0.33
Wdt_A=25

!...etc
Gosub "Create Object:"
ENDIF

...
IF ValueListParameter20=1 THEN
Len_ = 0.4
Ht_=1.33
Wdt_=58

!...etc
Gosub "Create Object:"
ENDIF
END
***********
"Create Object":
Len = Len_ 
Ht = Ht_ 
Wdt = Wdt_

!...etc
RETURN

The above 20 variables have suffixes A through to T say with unique values. In the Subroutine, if I could just change the variable suffix based upon the Gosub. Then the variables could all be stored cleanly at the start of the scipt, ready to be called and more easily managed. 

If I could write something like this:

!List of Variable Values to lookup:
Len_A = 0.2
Len_B=0.33
...
Len_T=0.43
Ht_A=58
...
Ht_T=58
Wdt_A=22
...
Wdt_T=32
!...etc

IF ValueListParameter1=1 THEN 
Suffix="A"
Gosub "Create Object":
ENDIF

...
IF ValueListParameter20=1 THEN 
Suffix="T"
Gosub "Create Object":
ENDIF
END

***********
"Create Object":
Len = "Len_" + Suffix 
Ht = "Ht_" + Suffix 
Wdt = "Wdt_" + Suffix 
!...etc
RETURN

Welcome any and all thoughts and many thanks, Matt

[Lingwisyer · Accepted solution]

...
Len_ = Len_A
goSUB
...
Len_ = Len_B
goSUB
...

Pretty sure what you were trying turns your parameter into a text type so that probably explains why it fails.

You could also play with matrices.

DIM Len[]
Len[1] = 0.2
Len[2] = 0.33
...
Suffix = 1
goSUB
...
CIRCLE2 = 0, 0, Len[Suffix]

Ling.

[GDL Enthusiast]

Wow that is a good idea! DIM could be the way to go, I will see how I go coding, clean scripts coming up. Thank you so much Ling! Matt

[Lingwisyer]

If you really wanted to, you could merge your Length (x), Width (y) and Height (z) parameters into a single two dimensional array.

[Jochen Suehlo]

There are a few cases in which variables can be composed of several parts.
Example:

_wall_scale = GLOB_SCALE
var = "Wall_" + STR(_wall_scale, 1, 0)

MATERIAL 1
GOSUB var

! ---------------------------- E N D ----------------------------------- !
! ---------------------------- E N D ----------------------------------- !

END  ! -- END -- END -- END -- END -- END -- END -- END -- END -- END -- !

! ---------------------------- E N D ----------------------------------- !
! ---------------------------- E N D ----------------------------------- !

"Wall_200":
	BLOCK 1, 1, 1
RETURN

! ---------------------------------------------------------------------- !
! ---------------------------------------------------------------------- !

"Wall_100":
	BLOCK 1, 2, 3
RETURN

! ---------------------------------------------------------------------- !
! ---------------------------------------------------------------------- !

"Wall_50":
	BLOCK 1, 4, 9
RETURN

! ---------------------------------------------------------------------- !
! ---------------------------------------------------------------------- !

[Lingwisyer]

The difference is that GOSUB is expecting a text string, which is what var is being defined as, whilst CIRCLE2 is expecting a numeric string or numberic parameter?