Multiple instances of jsep with different operators

[cmarcao]

Hi guys.

There is any reason to have a singleton parser? There is no chance to have more than one jsep with different configuration running in the same app at client side?

Thank you,

Carlos Marcão

[6utt3rfly]

@EricSmekens and @LeaVerou - any thoughts on this? I know when we first started moving into a plugin system, this was discussed, but then dropped to reduce complexity/scope. I feel like this could be useful in some cases and could be re-done similar to what this commit removed?

[LeaVerou]

Any proposal for additional complexity should be justified through use cases. What are the use cases for having multiple parsers with different configurations and how common are they?

[joeflateau]

@LeaVerou I would like to use jsep in a library with a custom binary operator but I cannot because of the singleton nature of it might lead to transient, hard to locate bugs

[Julusian]

I think what @joeflateau said sums it up for me.
If writing an application, then the singleton nature most likely isnt an issue.
But if writing a library, it could be an issue if some other component of the application also uses jsep.

I was considering using this for an application, where I would want to be able to parse boolean expressions and number expressions separately under different rules. While I could manage with this singleton, it would require swapping out the acceptable operators and things each time I want to parse an expression, which is rather wasteful.

[jdanyow]

related to #28