Error: [$parse:syntax] Syntax Error: Token ':' not a primary expression for filter option

[poshest]

I want to use a one time binding on a filter option, eg

{{ vm.unixDateNumber | date : ::vm.customDateFormat }}

but I get Error: [$parse:syntax] Syntax Error: Token ':' not a primary expression for filter option....

The vm.unixDateNumber can change (so I don't want it to be bound once), but the vm.customDateFormat will not.

[lgalfaso]

you cannot pick and choose, within one expression, what is one-time and what is not. In this case, an interpolation is one expression and only one expression

[poshest]

Well, yes, that is the way it is now. I forgot to mention this was a feature request, not a bug report! :)

[lgalfaso]

@poshest allowing for any part of an expression to be one-time binding would be a large effort and would imply the definition of a prefix operator ::. This would imply that this operator would need a priority. Eg the expression ::foo.bar() can have any of the following possible, all valid, valuations (::foo).bar(), (::(foo.bar))() or ::(foo.bar()) with all its consequences. Keeping an internal state and possible performance implications.

This is, without a clear use case that such feature would enable or that working with the existing mechanism involves a substantial amount of work, then it is not clear what benefits this syntax provides or justifies the amount of work

[poshest]

Well, I wasn't suggesting you would be able to put :: anywhere the way you suggest. Just at the start of major segments of common expressions like the date filter {{ date_expression | date : format : timezone}}, the way ng-repeat can understand the :: placed before the array ng-repeat="item in ::items".

But look, if it's lots of work or causes degradation in performance I'm in full agreement about closing this issue.