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joetesta's avatar
joetesta
Roku Guru
13 years ago

help debugging Invalid value for left-side of expression

Hello,

I'm trying to set up custom search history as described by RokuJoel here: viewtopic.php?f=34&t=49729&p=339297&hilit=roSearchHistory#p339297

However after the history is set, I'm seeing an error and my app is crashing:
Invalid value for left-side of expression. (runtime error &he4) in ...g:/source/appSearchScreen.brs(337)

337:       m.titlehistorylist[j]=histemp[i]


Apparently the roku doesn't like that I'm trying to set m.titlehistorylist with an index (even when j = 0), but I'm not sure why or what's different that prevented this problem in the example. As a workaround, I'm using 
m.titlehistorylist=histemp
but I presume this is reversing the desired order...

Can anyone give me a clue what's going wrong, why does the example work (or does it?) but this doesn't?
tyvmia
Roku Developer Program
  • RokuJoel's avatar
    RokuJoel
    Binge Watcher
    13 years ago
    What are the values of histemp and m.titlehistorylist?

    in the second example it appears you are assigning the whole histemp array to m.titlehistorylist which is essentially making m.titlehistorylist a pointer to histemp, if histemp is an array.

    - Joel
  • joetesta's avatar
    joetesta
    Roku Guru
    13 years ago
    Hi RokuJoel,
    i and j are both 0, histemp[0] should be the first (& only, in this case) stored value in the registry. m.titlehistorylist should be unassigned. Here's the function that's failing:

    function loadsearchHistory() 
      if not checkreg("history","search_title_hist") then
        ?"no title search history in the registry"
        createregsection("history","search_title_hist", "")
        m.titlehistorylist=""
      else
        ?"found title search history, loading"
        histemp=box(readreg("history","search_title_hist").tokenize(","))
        i=histemp.count()-1
        j=0
        while true
          if i=-1 or j > histemp.count() -1 
            exit while
          end if
          m.titlehistorylist[j]=histemp[i]
          'm.titlehistorylist=histemp
          i=i-1
          j=j+1
        end while
      end if
    end function


    And here's how I was putting the list in registry, based on viewtopic.php?f=34&t=49729&p=339297&hilit=roSearchHistory#p339297 and using the identical "arraytostring" function you posted there.
    function update_title_history(histlist As Object, querystring As String) As Dynamic
      flag=0
      ? "histlist = " Type(histlist)
      ? "querystring = " Type(querystring)

      if islist(histlist) = false
        ? "setting histlist[0] to " querystring
        histlist = CreateObject("roArray",1,1)
        histlist[0] = querystring
      else
        ? "looping over title history now"
        for i=0 to histlist.count()-1
          if querystring=histlist[i]
            flag=1
          end if
        next i

        if flag <> 1 then
          histlist.unshift(querystring)
          if histlist.count() > 9
            histlist.pop()
          end if
        end if
      end if

      m.titlehistorylist=histlist                                                                       
      writereg("history","search_title_hist",arraytostring(histlist))
      return histlist
    end function


    I noticed without this code that the list is reversing order each time the search screen is called, and then when there are more than 9 stored entries, it's keeping rather than discarding the oldest entries over newer ones.

    thanks a lot for any help,
    joe
  • joetesta's avatar
    joetesta
    Roku Guru
    13 years ago
    I could not figure out why that error happens, so I found a work-around. Now I am creating a temporary array to hold the reversed history and then I assign it to m.titlehistorylist after looping over the elements, like this:

    function loadsearchHistory() 
      if not checkreg("history","search_title_hist") then
        ?"no title search history in the registry"
        createregsection("history","search_title_hist", "")
        m.titlehistorylist=CreateObject("roArray", 1, true)
      else
        ?"found title search history, loading"
        histemp=box(readreg("history","search_title_hist").tokenize(","))
        temp1=CreateObject("roArray", 1, true)
        i=histemp.count()-1
        j=0
        while true
          if i=-1 or j > histemp.count() -1 
            exit while
          end if
          'm.titlehistorylist[j]=histemp[i]
          temp1[j]=histemp[i]
          i=i-1
          j=j+1
        end while
        m.titlehistorylist=temp1
      end if
    end function


    now it's working, although i still wish I understood why the error happens when trying to assign values to the m.titlehistorylist array...
  • joetesta's avatar
    joetesta
    Roku Guru
    13 years ago
    I figured out if I just declare 
    m.titlehistorylist =CreateObject("roArray", 1, true)
    before entering the loop, then it works as expected. I thought that 'm.titlehistorylist' was already array at this point in the app, but apparently not.