<div dir="ltr">Hi all,<div><br></div><div>Some questions as to the interactions between all three of these (attributes, arrays, and lists) and some discussion as to the desired functionality of each.</div><div><br></div><div>I've included (in raw text) some code at the end that demonstrates some of my concerns.</div><div><br></div><div>First: Is it possible for individual elements of an array to maintain their individual attributes while in an array? (Parts 1/2 below)</div><div>Current practice is to set any individual attributes to the attributes of the array variable and, when individual elements are returned, return the elements with all attributes from the array, even if the attributes have been changed or others added.</div><div><br></div><div>Secondly, I know Lists are relatively new additions to NCL, but I'd also like to question how variables are handled when the lists are being created. (Parts 3/4 below)</div><div>It seems that there is not a functional way to create a list without having a unique variable for each member (e.g. Part 3). This is a nice workaround to my question above, as each member keeps its own attributes as well.</div><div>However, in order to use these lists in a more practical sense, the addition of a variable via a loop does *not* work well, although I believe it is working as designed. When a variable is added to a list, the original variable must be maintained in memory and any changes to that variable outside of the list will be reflected inside the list as well. This makes sense, as the variable is simply a member of the list - the list is simply an organizational structure for pre-existing variables. In order to do this in a loop, one would need to have a unique name for each variable to be added to the list OR disassociated the variable that is being added to the list from its reference variable outside the list. The unique_string function, while useful for attribute names, does not work for variable names, e.g.</div><div><br></div><div>varname = unique_string("")</div><div>$varname$ = ....data to put in list...</div><div><br></div><div>As a result, lists are essentially useless without a unique, hand-made variable for each member, something that is simply not practical in many situations.</div><div><br></div><div>The biggest red flag I've seen, however, is when trying to add only the value of the variable, via (/.../), to the list. This would be a potential alternative to creating individual variables and allowing for subsequent alterations to the variable in order to add attributes, for example. The subsequently created list, when popped with ListPop, instantly seg faults.</div><div><br></div><div>As I write this email, I realize that my Java training from many years ago comes to mind, especially the ArrayList functionality. I'm not 100% sure that's what I've tried to describe in this email, but it might be a start, where "objects" (any variable with attributes) can be stored (like lists) but with the index functionality of arrays as well. It still doesn't get around the "unique name" issue, however. Thanks for reading...I'm sure these are lofty goals to see any of this in the future, but the apparent desire to add lists tells me there is some motivation for this type of data structure even if the current utility of Lists seems unintentionally low.</div><div><br></div><div><br></div><div>Kyle</div><div><br></div><div>test code (on 64-bit RHEL, 6.2.1):</div><div><div>begin</div><div><br></div><div> a = True</div><div> a@thing = 1</div><div> a@thing2 = 2</div><div> b = True</div><div> b@thing = 10</div><div> b@thing3 = 20</div><div> c = True</div><div> c@thing = 100</div><div> c@thing2 = 200</div><div><br></div><div> ;Part 1</div><div> arraylist = new(3,typeof(a))</div><div> arraylist(0) = a</div><div> arraylist(1) = b</div><div> arraylist(2) = c</div><div> print(arraylist(0)) ;expecting value/atts of a</div><div> k = arraylist(0)</div><div> print(k@thing) ; keeps atts of arraylist, which are those of c</div><div> delete(k)</div><div> print("###############################")</div><div> ;Part 2</div><div> arraylist2 = (/a,b,c/)</div><div> print(arraylist(0))</div><div> k = arraylist(0)</div><div> print(k@thing) ; does same as first example.</div><div><br></div><div> print("###############################")</div><div> ;Part 3</div><div> thelist = NewList("fifo")</div><div> ListPush(thelist,a)</div><div> ListPush(thelist,b)</div><div> ListPush(thelist,c)</div><div> print(thelist) ; keeps values AND attributes</div><div><br></div><div> print("###############################")</div><div> ;Part 4</div><div> looplist = NewList("fifo")</div><div> looplist2 = NewList("fifo")</div><div> do i=0,2</div><div> thevar = i</div><div> thevar@att1 = i*12.0</div><div> ListPush(looplist,thevar)</div><div> ListPush(looplist2,(/thevar/))</div><div> end do</div><div> print(looplist)</div><div> y=ListPop(looplist)</div><div> print("First var from list, should be 0 with att of 0:")</div><div> print(y)</div><div> print("###############################")</div><div> print(looplist2)</div><div> print("###############################")</div><div> x=ListPop(looplist2) ; SEG FAULT here.</div><div> print(x)</div><div><br></div><div>end</div></div><div><div><div class="gmail_signature"><div dir="ltr">----------------------------------------<div>Kyle S. Griffin</div><div>Department of Atmospheric and Oceanic Sciences</div><div>University of Wisconsin - Madison</div><div>Room 1421</div><div>1225 W Dayton St, Madison, WI 53706</div><div>Email: <a href="mailto:ksgriffin2@wisc.edu" target="_blank">ksgriffin2@wisc.edu</a></div></div></div></div>
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