EL from HFSJ

[kapil munjal]

I was going through chapter 8 of HFSJ and came through this EL
on page 394.

${requestScope[integer] ne 4 and 6 le num || false}

This whole expression return false but I am not able to find out how.

Could someone explain!

[J Johny Rufus]

Hi Kapil Munjal,

"${requestScope[integer] ne 4 and 6 le num || false}"

can be splitted into three subsets,

1. requestScope[integer] ne 4 AND
2. 6 le num OR
3. false

so, if either 1 or 2 evaluates to false , then the expression becomes

1) either as false AND true OR false --> false OR false --> FALSE
2) or as true AND false OR false --> false OR false --> FALSE

Hope this helps

Thanks and Regards,
Rufus

[kapil munjal]

Johny,

Could you tell what "requestScope[integer]" will return.

[Narendra Dhande]

Hi,

I thnk it will return null. what is about num in the EL?

Thanks

[kapil munjal]

Please go to page 394 of HFSJ and you will find the question.

[sergio mendez-rueda]

Originally posted by kapil munjal:
Please go to page 394 of HFSJ and you will find the question.

requestScope[integer] return 0 but
requestScope["integer"] or requestScope['integer'] return 3
cheers

[H Singh]

Hello Sergio:

Can you please explain why would
requestScope[integer] return 0 but
requestScope["integer"] or requestScope['integer'] return 3

Thanks

[kapil munjal]

Can you please explain why would
requestScope[integer] return 0 but
requestScope["integer"] or requestScope['integer'] return 3

requestScope[integer] return 0

- It will look for a attribute with the name 'integer', and it will find the value of this attribute as 3. But till now this expression has not looked into requestScope. Its just the EL which is being processed. Now, it will look for the 4th element in the requestscope and it will not find anything as there are only 3 elements (0,1,2). So, it will return 0.


But it we do this -
requestScope["integer"] or requestScope['integer'] return 3

It will look for a map value with the key 'integer' and it will find the second key in the map and return the value 3.

[sergio mendez-rueda]

Originally posted by kapil munjal:


requestScope[integer] return 0

- It will look for a attribute with the name 'integer', and it will find the value of this attribute as 3. But till now this expression has not looked into requestScope. Its just the EL which is being processed. Now, it will look for the 4th element in the requestscope and it will not find anything as there are only 3 elements (0,1,2). So, it will return 0.


But it we do this -
requestScope["integer"] or requestScope['integer'] return 3

It will look for a map value with the key 'integer' and it will find the second key in the map and return the value 3.

Hi Kapil,
your explanation is fine!!

thanks,
sergio
-----
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--Dorothy, from the Wizard of Oz