Suggestion: implement ternary conditionals

[mklement0]

C-style ternary conditionals would be a handy addition to the language.

For instance, instead of writing:

if ((get-date).tostring("ss") % 2) { 'odd'  } else  { 'even' }

one could write:

(get-date).tostring("ss") % 2   ?   'odd'   :    'even'

It would also relieve a long-standing disappointment:

At Microsoft, “to ship is to choose”. One of the things we were very disappointed in not being able to ship in V1.0 is a ternary operator.

From a PowerShell Team blog post dated 29 December 2006.

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Related: implement null-coalescence and null-soaking and null-conditional assignments

[BrucePay]

Note that with the change to allow assignments from statements, the need for a ternary operator is reduced. You can simply do
$var = if ($x) { $x } else { $y }
It's not as concise as the ternary operator but is arguably more readable.

[mklement0]

Yes, though you still have to use $(...) in addition if the conditional is part of a larger expression:

'The current sec. is ' + $(if ((get-date).tostring("ss") % 2) { 'odd'  } else  { 'even' })

vs.

'The current sec. is ' + ((get-date).tostring("ss") % 2   ?   'odd'   :    'even')

I know that readability is in the eye of the ... uh ... reader, but I personally find the latter visually easier to parse, and having to type less is always a bonus.

With such a frequently used feature, I think remembering the more abstract ternary syntax wouldn't be a problem (and, of course, people can continue to use if, if they prefer).

[thezim]

@mklement0 I have to agree later has less cognitive load.

[powercode]

This is definitely on my top list to.
@BrucePay, are there any reasons that this would be a bad idea? Or is it just about 'to ship is to choose' ?

[lzybkr]

In the past, this feature request was turned down as being harder for less experienced scripters to understand, and that the expression form of the if statement was a clearer, though more verbose alternative.

My personal perspective: if the language was just for me, I'd probably have added it a long time ago. But ... I find many developers don't use it, which actually suggests there is some truth to the hypothesis that less experienced folks will have trouble with the ternary operator.

[mklement0]

@lzybkr:

It's worth distinguishing between active use of a feature vs. the ability to recognize and understand it.

Clearly, everyone gets to choose whether to use such a feature, but are you saying that "have trouble with" means that less experienced folks won't understand it when they see it in the code of others?

[lzybkr]

@mklement0 - we introduced $psitem as an alias for $_ because of sufficient feedback that $_ was cryptic and confusing, so I do believe the ternary operator would be difficult for some less experienced people to understand.

[powercode]

On the other hand, there are many elements in PowerShell that are confusing to beginners, or even to quite experienced developers.

As with any other language, it takes some effort to learn the syntax and meaning of language constructs.
I don't know if I think the ternary operator is especially difficult to grasp.

Do you have data suggesting that it is?

[lzybkr]

I believe the only data is anecdotal, but the criticism applies to any cryptic language - bash, perl, etc.

And to be clear, I was providing the historical context. Maybe PowerShell is ubiquitous enough now that more cryptic syntax won't affect adoption.

Also keep in mind - some terse languages still use if/then as the ternary operator, e.g. F#.

That said, maybe it's possible to use fewer characters and not be too cryptic:

if ($x) { $y } else { $z }
$x -then $y -else $z
$x ? $y : $z

-then/-else fits well with PowerShell syntax - but, an operator (or operators if it's too confusing to think of as a single operator), you gain the benefit of not needing parens and braces.

Then again, this is asking for trouble similar to foreach vs. foreach-object. but maybe it's not as bad, I don't know.

[mklement0]

@lzybkr:

Cryptic in homeopathic doses is healthy:

PowerShell is commendably not cryptic overall, but in some cases offers cryptic syntax as a concise alternative (you still can be verbose if desired) for frequently used constructs, notably ? for Where-Object and % for ForEach-Object.

Providing $x ? $y : $z as a concise alternative to if ($x) then { $y } else { $z } to me is in the same spirit.

The cryptic aspect is ameliorated by ? being reminiscent of a question and therefore suggesting a conditional (albeit one preceding the ? in this case), and - more importantly - being a potentially familiar construct from several other languages, with the same fundamental semantics.

You don't get the same benefit with $x -then $y -else $z: it is not familiar.

Also, while many PS operators do have symbolic names, many do not: * / + % ...
These are inherently cryptic too, we just don't perceive them that way anymore, because they are so familiar and ubiquitous.

My sense is that $x ? $y : $z too is already familiar to many, and will become even more so once introduced into the language, given the frequent need for concise conditionals.