Forum OpenACS Development: Re: category map object

3: Re: category map object (response to 2)
Posted by Iuri Sampaio on

The problem is very basic, however a bit tricky: How to manipulate the name of the vars, in order to get them dynamically set. The category's ad_form elements have their names as cat_0356, cat_098 ...

That means 0356 is the category id and $cat_0356 is also a variable that contains the category of the child.

I am trying to deal with something like $cat_${category_id} but i get the following error bellow.

For example in the loop:

foreach {category_id category_name} [videos::get_categories -package_id $package_id] {
set tmp "$cat_${category_id}"
ns_log Notice "$tmp"


why doesn't $cat_${category_id} become $cat_0356 and moreover it does not write the value held in $cat_0356?

[04/Jun/2010:10:16:15][4386.3056024464][-default:0-] Error: POST
referred by "";
can't read "cat_": no such variable
while executing
"set tmp "$cat_${category_id}""
("foreach" body line 2)
invoked from within
"foreach {category_id category_name} [videos::get_categories -package_id $package_id] {
set tmp "$cat_${category_id}"
ns_log Notice "$temp"

("uplevel" body line 9)
invoked from within
"uplevel #$level $on_submit"
(procedure "ad_form" line 620)
invoked from within
"ad_form -extend -name video -form {
} -new_request {
set creator [videos::get_user_name -user_id [ad_conn user_id]]
set read_term 0
} -edit_re..."
("uplevel" body line 80)
invoked from within
"uplevel {
ad_page_contract {
This is a form to upload video

4: Re: category map object (response to 3)
Posted by Dave Bauer on
You want to review how Tcl works

The answer is simple, there are many examples around the toolkit of dynamic variable names.

[set cat_${category_id}] will return the value of the variable you are looking for.

$cat_${category_id} is parsed as $cat_ $category_id since the parser does not do to passes.

NOTE that the index of an array is evaluated betfore the variable reference so $cat($category_id) will work where $cat_${category_id} will not.

5: Re: category map object (response to 4)
Posted by Iuri Sampaio on
Thanks dave,

i tried to "read the manual" but it ended up i was just browsing the whole site looking for examples because i didn't know how do precisely call the problem i had in order to focus my research.

best wishes