[XQuery Talk Mailing List Archive Home] [By Date] [By Thread] [By Subject] [By Author] [Recent Entries] [Reply To This Message]

a conceptual clarification

Bas de Bakker bas at x-hive.com
Fri Mar 4 13:41:12 PST 2005


use object in java
Shadowing a variable with another variable with the same name is 
possible in many languages, including Java.  It is also generally 
confusing and therefore considered bad practice (although I do not agree 
that it should be disallowed).  In this respect there is nothing special 
about XQuery.

I fail to see why you would consider using a let statement within a for 
statement to be confusing, nor do I see a better alternative.  This is 
just like

for (int i = 0; i < n; ++i) {
     Object object = a[i];
     // Use object
}

in Java, which is an extremely common way of programming in many languages.

Regards,
Bas de Bakker


Amitabh Ojha wrote:
> Dear Sir,
> 
> It has been a very useful exchange of  messages/ replies from experts on 
> this theme. However, no discussion has taken place as yet on  one point 
> which I had flagged earlier.  I elaborate it here. 
> 
> It is evident now  that  it is a bad practice to have two let 
> statements, one after the other, define a variable  with the same name,  
> as  is  cited  in the following example  (even if it is not illegal as 
> per XQuery Specs)
> 
> let $x := ……
> let $x := ……
> 
> Following from this, will it be correct to assume that  the appearance 
> of a let statement after a for statement be also treated as equally 
> undesirable and error-prone programming technique in XQuery (because in 
> course of  iteration,  a let statement is then forced to rebind  the 
> same variable name say  $x several times, probably forcing it to bind to 
> a new value each time).  I cite two examples here. In case of  my:foo () 
> the result is same as one would expect in Java i.e  1, 2, 3, 4, 5. But 
> in case of  my:bar () we get 101, 102, 103, 104, 105 – this is not what 
> a Java programmer will expect (although in XQuery context one knows why 
> it is so).
> 
> declare function my:foo ()
> {
> for $i in (1 to 5)
> let $x := $i
> return $x
> };
> 
> declare function my:bar ()
> {
> let $x := 100
> for $i in (1 to 5)
> let $x :=  $x  +  $i
> return $x
> };
> 
> Regards.
> 
> Amitabh Ojha


PURCHASE STYLUS STUDIO ONLINE TODAY!

Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced!

Buy Stylus Studio Now

Download The World's Best XML IDE!

Accelerate XML development with our award-winning XML IDE - Download a free trial today!

Don't miss another message! Subscribe to this list today.
Email
First Name
Last Name
Company
Subscribe in XML format
RSS 2.0
Atom 0.3
Site Map | Privacy Policy | Terms of Use | Trademarks
Free Stylus Studio XML Training:
W3C Member
Stylus Studio® and DataDirect XQuery ™are products from DataDirect Technologies, is a registered trademark of Progress Software Corporation, in the U.S. and other countries. © 2004-2013 All Rights Reserved.