Looking back at the PEP ( https://www.python.org/dev/peps/pep-0308/ ), it
seems that the main argument was that people were working around the lack
of it in ways that led to subtle bugs using 'and' and 'or'. I seem to have
inadvertently demonstrated that it's possible to do this in an obfuscated
(and not 0-alloc) way in go, so in principle this same argument applies
:-). But unless my crazy ternary operator catches on (I assure you, I only
*very* rarely use it in real code), this argument can be considered moot.
To me the biggest reason to want a ternary operator is to make it easier on
the reader of the code. If there's anything that go and python have in
common, it's that both languages are designed to be easy to read (though
with notable differences in emphasis about what makes it easy), and also
relatively easy to tell whether code is correct.
With a ternary, it's very clear that after the statement, the assignment
has occurred.
result = test ? "a" : "b"
With an `if' statement, you have to read a bit more:
var result string
if test {
result = "a"
} else {
result = "b"
}
In most cases the analysis is very simple to tell that both code branches
assign to `result'. But there's a problem with this. This is only easy to
see if someone doesn't then come along and insert extra code into those
nice welcoming code blocks:
var result string
if test {
result = "a"
// insert code here
funcCall()
} else {
// insert other code here
funcCall2()
result = "b"
}
As a result, as the code is modified, the condition that 'result has a
value' is not held and you end up with the zero value instead of something
you expected.
Of course it's not as bad as in python or C because there is a separate `='
and `:=' operator, but as you can see above, this doesn't always come into
play. If you're assigning more than just an immediate constant, you
probably don't want to start with `:=' and then re-assign based on the
conditional.
It also gets much more complicated to follow for cases where you might want
to use a nested or chained ternary expression, or a more complicated value
construction which has many ternaries within it.
I've lost count of the times I've had to change:
return FooBar{
Field: blah,
}
To:
var foo FooBar
if someCond {
foo.Field = blah
} else {
foo.Field = bar
}
return foo
In my experience code is clearer and easier to read if it does *not*
contain re-assignments and branches, and temporary variables used only
once. With a ternary operator, you can code like that for cases where it
makes sense. I would much rather write:
return FooBar{
Field: someCond ? blah : bar,
}
my 2¢,
Sam
On Wed, Aug 15, 2018 at 1:13 AM, 'Axel Wagner' via golang-nuts <
golang-nuts@googlegroups.com> wrote:
> In my opinion Python serves as a poor argument here. I tend to use Python
> as a example of a grab-bag language that adds any feature anyone considers
> useful - without considering the cost. An Anti-Go, if you will :)
> Gustavo Niemeyer actually wrote this up pretty well:
> https://blog.labix.org/2012/06/26/less-is-more-and-
> is-not-always-straightforward
>
> So, from my perspective, if you tell me "Python did not have ternary
> operators, but after long and hard discussions, they caved", what I'm
> hearing is "even *Python* didn't really need them". ;)
>
> (Disclaimer: This isn't meant as a dig at Python. I think Python is a
> great language. But its design goals are very different from Go's)
>
> On Wed, Aug 15, 2018 at 8:33 AM Sam Vilain <s...@vilain.net> wrote:
>
>> I haven't seen all the discussion referenced, but I remember digging deep
>> into the python language archives where Guido and others eventually
>> relented and added ternaries (with the syntax "a if val else b"). I can't
>> remember the argument which swung the consensus but the arguments against
>> seem remarkably similar.
>>
>> Go does have a one-line ternary:
>>
>> var result = map[bool]string{false: "a", true: "b"}[test]
>>
>> It's less of a hack if you declare the lookup "table" separately.
>>
>> Sam
>>
>> On Aug 14, 2018 9:52 PM, Agniva De Sarker <agniva.quicksil...@gmail.com>
>> wrote:
>>
>> Your answer is here - https://tip.golang.org/doc/
>> faq#Does_Go_have_a_ternary_form.
>>
>>
>> On Tuesday, 14 August 2018 22:13:37 UTC+5:30, Mark Volkmann wrote:
>>
>> I’m new to Go and I imagine the idea of adding a ternary operator to Go
>> has been discussed many times. Rather than repeat that, can someone point
>> me to a discussion about why Go doesn’t add this? I’m struggling to
>> understand why it is desirable to write code like this:
>>
>> var color
>> if temperature > 100 {
>> color = “red”
>> } else {
>> color = “blue”
>> }
>>
>> Instead of this:
>>
>> var color = temperature > 100 ? “red” : “blue”
>>
>> Is the ternary really so confusing that it justifies writing 6 lines of
>> code instead of 1? I realize I could eliminate two lines like the
>> following, but this isn’t a good idea if the values come from function
>> calls since there would sometimes be needless function calls.
>>
>> var color = “blue”
>> if temperature > 100 {
>> color = “red”
>> }
>>
>> ---
>> R. Mark Volkmann
>> Object Computing, Inc.
>>
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