eval works in global scope but returns its result locally, so something
like this works easily enough:
rulestrs = ["x[1] && x[2]", "x[3] || x[4]", "x[1] && (x[2] || x[3])"]
function evaluate(rules, boolList)
rulefuncs = [eval(parse(string("x -> ", rule))) for rule in rules]
Bool[rf(boolList) for rf in rulefuncs]
end
evaluate(rulestrs, [true, false, true, false]) #output: Array{Bool,1} -
[false,
true, true]
Note the the Bool is required for the comprehension to get the correct
output type because the compiler has no idea that all the anonymous
functions return Bools.
On Tuesday, April 26, 2016 at 2:24:18 PM UTC-4, Ali Rezaee wrote:
>
> Reading the rules from a file, how can I convert the strings to such
> anonymous functions?
>
> On Tuesday, April 26, 2016 at 6:48:21 PM UTC+2, Josh Langsfeld wrote:
>>
>> Maybe a better design would be to store the rules as anonymous functions
>> rather than code strings? Something like:
>>
>> ```
>> rules = [(x -> x[1] && x[2]), (x -> x[3] || x[4])] #parentheses not
>> required
>> result = [rule(boolList) for rule in rules]
>> ```
>>
>> On Tuesday, April 26, 2016 at 12:09:33 PM UTC-4, Ali Rezaee wrote:
>>>
>>>
>>> Thanks for your replies.
>>> My objective is exactly what the code shows. I have a list of Boolean
>>> expressions similar to the examples in the code, and I need to evaluate
>>> them one by one based on x values.
>>> So writing a macro would be the only solution.
>>>
>>> Best regards
>>> On Tuesday, April 26, 2016 at 5:38:21 PM UTC+2, Ali Rezaee wrote:
>>>
>>>> Hi everyone,
>>>>
>>>> I am trying to run the code below. When I try the code outside of a
>>>> function and in REPL, it runs successfully. However when I run it using a
>>>> function it throw an error.
>>>> Why do I get the error? and how can I solve this problem?
>>>>
>>>> Thanks in advance for your help.
>>>>
>>>> rules = ["(x[1] && x[2])", "(x[3] || x[4])"]; # a list of boolean
>>>> expressions
>>>> boolList = [false, true, false, true]; # a boolean vector for every x
>>>> in rules
>>>>
>>>> function evaluate(rules, boolList)
>>>> x = boolList
>>>> result = Array{Bool}(length(rules))
>>>> for (i, rule) in enumerate(rules)
>>>> result[i] = eval(parse(rule))
>>>> end
>>>> return result
>>>> end
>>>>
>>>> evaluate(rules, boolList)
>>>> # ERROR: UndefVarError: x not defined
>>>>
>>>> # but This will work:
>>>> x = boolList
>>>> result = Array{Bool}(length(rules))
>>>> for (i, rule) in enumerate(rules)
>>>> result[i] = eval(parse(rule))
>>>> end
>>>>
>>>> result
>>>> # 2-element Array{Bool,1}: false true
>>>>
>>>>
>>>>
