Feature #11734: Improved ternary operator

• Status: Closed
• Assignee: -
• Target version: -

In ternary operator it would be nice to be able to pass expression result from condition into value_if_true/value_if_false in such way:

some_long_expression ? &.to_s : 'foobar'
where & refers to some_long_expression

Instead of doing:
some_long_expression ? some_long_expression.to_s : 'foobar'

or:
result = some_very_very_long_expression result ? result.to_s : 'foobar'

[Hanmac (Hans Mackowiak)]

why not:

(x = some_long_expression) ? x.to_s : 'foobar'

[danielpclark (Daniel P. Clark)]

& is associated more with proc. I think _ would be closer to the kind of thing you're looking for.

some_long_expression = :baz
_ ? _.to_s : 'foobar'
# => "baz"

Although I tried in-lining it with a semicolon and found that the _ feature only works off of the previous' lines results. So the following won't work.

:buzz; _ ? _.to_s : 'foobar'
# => "foobar"

And this doesn't work

x = 4
:fiz ? _.to_s : 'foobar'
# => "4"

So if you don't mind putting your ternary operation on the next line you can just use _

[Hanmac (Hans Mackowiak)]

@Daniel: _ with previous line result is a feature of IRB and PRY not ruby itself

[nobu (Nobuyoshi Nakada)]

Maybe some_long_expression&.to_s || 'foobar' ?

Hans Mackowiak wrote:

why not:

(x = some_long_expression) ? x.to_s : 'foobar'

think it's not good. Ruby 2.2.3p173 shows warning:

warning: found = in conditional, should be ==

Nobuyoshi Nakada wrote:

Maybe some_long_expression&.to_s || 'foobar' ?

@Nobuyoshi, thanx! safe navigation from 2.3 solves such tasks.

[Hanmac (Hans Mackowiak)]

Yurko Bregey wrote:

Hans Mackowiak wrote:

why not:

(x = some_long_expression) ? x.to_s : 'foobar'

think it's not good. Ruby 2.2.3p173 shows warning:

warning: found = in conditional, should be ==

you might did something wrong because on "ruby 2.3.0dev (2015-11-25 trunk 52749) [x86_64-linux]" it doesn't show any warning for me

[ko1 (Koichi Sasada)]

• Status changed from Open to Closed