'const' binding construct in predicates and preconditions

sebastian_egner

This is a suggestion for a minor addition to the FeatureScript language.

The 'const' binding construct (a.k.a. 'let' in other languages) is extremely helpful for introducing short lived abbreviations in functions. It would be useful to have it available in the predicate language as well.

For a contrived example consider:

{ const x = veryLongVariableName.someFieldNameWhichHasManyCharacters;
  f(x) == [x,x,x]; }

This is a minor addition because there are effective workarounds. You can either define a helper predicate, or use

{ for (var x in [veryLongVariableName.someFieldNameWhichHasManyCharacters])
    f(x) == [x,x,x]; }

which is an implicit way of saying what you mean.

ilya_baran

Thanks for the suggestion.  Just so I understand: do you want to use this primarily in the UI-defining feature preconditions or in non-feature predicates and preconditions?  In other words, would it be enough if const were allowed or would it need to be also a valid part of a UI spec?

sebastian_egner

ilya_baran said:

Thanks for the suggestion.  Just so I understand: do you want to use this primarily in the UI-defining feature preconditions or in non-feature predicates and preconditions?  In other words, would it be enough if const were allowed or would it need to be also a valid part of a UI spec?

Hi Ilya,
I am thinking of the language allowed between curly braces after he 'predicate' and 'precondition' keywords, not after 'annotation'. So I guess that makes it the non-feature predicates and preconditions.

ilya_baran

Ok, easy enough.  You should see this in not-too-long (though not the next update).