# Scripting an AND conditional...Single Line "If" or Nested "If"s?

**URL:** <https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084>\
**Category:** Lounge (Discussions)\
**Created:** [May 6, 2021, 2:03pm UTC](https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084 "2021-05-06T14:03:19Z")\
**Posts on this page:** 11\
**Page:** 1

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**Author:** ![tonywhitelive](https://yyz2.discourse-cdn.com/flex030/user_avatar/the.fmsoup.org/tonywhitelive/32/208_2.png) [@tonywhitelive](https://the.fmsoup.org/u/tonywhitelive)\
**Post date:** [May 6, 2021, 2:03pm UTC](https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084/1 "2021-05-06T14:03:19Z")

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Which method for scripting an AND conditional do you prefer?

- Single "If"
- Nested "If"s

Does the Single "If" method "short circuit" (a good thing in this context)?

![image](https://canada1.discourse-cdn.com/flex030/uploads/fmsoup/original/2X/2/237352c09c2551f41b4cb4daa2057e527e1e2a28.png)

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**Author:** ![MonkeybreadSoftware](https://yyz2.discourse-cdn.com/flex030/user_avatar/the.fmsoup.org/monkeybreadsoftware/32/361_2.png) [@MonkeybreadSoftware](https://the.fmsoup.org/u/MonkeybreadSoftware)\
**Post date:** [May 6, 2021, 3:05pm UTC](https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084/2 "2021-05-06T15:05:37Z")

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The first is more compact, but I often prefer the second as I have two lines for debugger to stop to see the result of each IF check.  
And I can use two ELSE for handling other cases.

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**Author:** ![tonywhitelive](https://yyz2.discourse-cdn.com/flex030/user_avatar/the.fmsoup.org/tonywhitelive/32/208_2.png) [@tonywhitelive](https://the.fmsoup.org/u/tonywhitelive)\
**Post date:** [May 6, 2021, 4:14pm UTC](https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084/4 "2021-05-06T16:14:43Z")

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Good points.

![image](https://canada1.discourse-cdn.com/flex030/uploads/fmsoup/original/2X/0/07a98c1ada4611d671019edc6c7a255a89bd571e.png)

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**Author:** ![Malcolm](https://yyz2.discourse-cdn.com/flex030/user_avatar/the.fmsoup.org/malcolm/32/196_2.png) [@Malcolm](https://the.fmsoup.org/u/Malcolm)\
**Post date:** [May 6, 2021, 11:15pm UTC](https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084/5 "2021-05-06T23:15:37Z")

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I love guard clauses. They are clear and concise.

```
If [not CF_gui_client]
    exit script
End If
# go ahead, we have GUI client

```

Much more readable and easier to maintain than the alternative

```
If [CF_gui_client]
    ...
    ... hundreds of lines of code ...
    ... many IF clauses
    ...
End If <<-- who does this belong to?
```

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**Author:** ![Torsten](https://yyz2.discourse-cdn.com/flex030/user_avatar/the.fmsoup.org/torsten/32/1574_2.png) [@Torsten](https://the.fmsoup.org/u/Torsten)\
**Post date:** [May 7, 2021, 5:20am UTC](https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084/6 "2021-05-07T05:20:03Z")

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It depends. If the second clause has a single condition, a single ‘If’ line is fine and produces readable code. If the second clause has multiple conditions to check ‘Else If’, the nested version is easier to read.

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**Author:** ![bdbd](https://yyz2.discourse-cdn.com/flex030/user_avatar/the.fmsoup.org/bdbd/32/620_2.png) [@bdbd](https://the.fmsoup.org/u/bdbd)\
**Post date:** [May 7, 2021, 10:30am UTC](https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084/7 "2021-05-07T10:30:25Z")

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Guard clauses can create problems. For example:

```
# Initialization.
Go to Layout ["Some Layout" (Some Table) ; Animation: None]
... other initialization code ...

# Guard clause
If [some if condition]
    Exit Script [some exit condition]
End If

... more code ...

# Cleanup.
Go to Layout [original layout ; Animation: None]
... other cleanup code ...

```

I use what I call error-based code execution when warranted. For example:

```
# Initialization.
Set Variable [$error ; 0 // No error]
Go to Layout ["Some Layout" (Some Table) ; Animation: None]
... other initialization code ...

# Validation.
If [some if condition is not met]
    Set Variable [$error ; -1 // Or any other error code]
End If

# Code block 1.
If [not $error]
    ... some code ...
    ... which may set the $error value ...
End If

# Code block 2.
If [not $error]
    ... same idea as code block 1 ...
End If

... more code blocks ...

# Cleanup.
Go to Layout [original layout ; Animation: None]
... other non conditional cleanup code ...
If [$error]
    ... conditional cleanup code ...
End If

# Return.
Exit Script [some exit condition]

```

I find it readable and easy to debug. Admittedly wordy.

Hope this helps.

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**Author:** ![Bobino](https://yyz2.discourse-cdn.com/flex030/user_avatar/the.fmsoup.org/bobino/32/194_2.png) [@Bobino](https://the.fmsoup.org/u/Bobino)\
**Post date:** [May 7, 2021, 1:55pm UTC](https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084/8 "2021-05-07T13:55:01Z")

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@bdbd Anything specific that would make you prefer the pattern you describe over a single pass loop?

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**Author:** ![rivet](https://yyz2.discourse-cdn.com/flex030/user_avatar/the.fmsoup.org/rivet/32/1727_2.png) [@rivet](https://the.fmsoup.org/u/rivet)\
**Post date:** [May 7, 2021, 3:39pm UTC](https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084/9 "2021-05-07T15:39:06Z")

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I am a fan **exit loop if** especially running transactions

```
// RUN
Loop  	
 

   … do something
  Set Variable [ $error ; 
    Value: JSONSetElement ( "" ; 	
    ["code" ; Get (LastError) ; JSONNumber] ;
    ["message" ; "error" ; JSONString] )
  ] 
  Exit Loop If [JSONGetElement ( $error ; "code" ) > 0] 

  … do something again
  Set Variable [ $error …
  Exit Loop If [JSONGetElement ( $error ; "code" ) > 0] 

  Exit Loop If [True] //terminate loop
End Loop

// REUSLT
If [JSONGetElement ( $error ; "code" ) > 0] 
	
	Revert Record/Request [With dialog: Off]
	Set Variable [$result ; Value: $error] 

Else

Set Variable [ $result ; 
	Value: JSONSetElement ( "" ; 	
	["error.code" ; 0 ; JSONNumber] ;
	["error.message" ; "success" ; JSONString];
	["data" ; $data ; JSONObject] )
] 

End If

Exit Script [Text Result: $result]
```

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**Author:** ![flybynight](https://yyz2.discourse-cdn.com/flex030/user_avatar/the.fmsoup.org/flybynight/32/1023_2.png) [@flybynight](https://the.fmsoup.org/u/flybynight)\
**Post date:** [May 9, 2021, 11:06pm UTC](https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084/10 "2021-05-09T23:06:04Z")

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Yes, I have become a big fan of the "Single pass loop" method of constructing a script, with exit clauses that set variables like $ErrorCode, $ErrorDescription, etc. And of course, have cleanup steps at the end, outside the master loop.

But I think the original post was more a question of logical branching. That would still exist inside the overall single pass loop.

As with all things "it depends" but if the 2 conditions to evaluate are really simple (or already exist in variables for another reason), I would do that If in 1 line. If the 2 conditions are complicated and yet to be evaluated, I'll test the easier one (or the one more likely to fail the IF test), therefore short-circuiting the need for the need for second evaluation.

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**Author:** ![bdbd](https://yyz2.discourse-cdn.com/flex030/user_avatar/the.fmsoup.org/bdbd/32/620_2.png) [@bdbd](https://the.fmsoup.org/u/bdbd)\
**Post date:** [May 10, 2021, 2:25am UTC](https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084/11 "2021-05-10T02:25:46Z")

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Was forgetting to answer…

I am no fan of single pass loops. I understand that they emulate object-oriented programming's (OOP) try (and similar) clause. While they make sense in OOP, the low-level programmer in me is not fond of spaghetti branching… which is essentially what an exit loop if statement does.

I'm pretty certain I am just being stubborn. That said, I prefer error-based code execution… more wordy, easy to follow and it handles more than just exclusion clauses.

Hope this helps.

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**Author:** ![steve\_ssh](https://yyz2.discourse-cdn.com/flex030/user_avatar/the.fmsoup.org/steve_ssh/32/160_2.png) [@steve\_ssh](https://the.fmsoup.org/u/steve_ssh)\
**Post date:** [May 10, 2021, 2:42am UTC](https://the.fmsoup.org/t/scripting-an-and-conditional-single-line-if-or-nested-if-s/2084/12 "2021-05-10T02:42:23Z")

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Been really appreciating seeing others' thoughts on this. Wasn't originally going to weigh in because I felt it might just repeat already posted content, but here it goes:

- I don't much care for the nested Ifs, but there are cases (as mentioned by @flybynight), where I might sometimes use something similar to defer evaluating a potentially costly operation.

- Though I often use compound conditions within a single IF, I have usually already evaluated the expressions in preceding lines, so that the IF statements can be comprised of variables that lend themselves to what I personally find readable.

As an example:

`If( $_login_is_current AND $_operation_is_valid )`

is an example of how I like my IF conditions to read.

That said -- I don't draw an absolute line on this aesthetic. If the calculation happens to be easily grokable on its own, I do not insist on first setting it to a variable. This is, of course a judgement call.