[Pmw-general] Follow up on memory leak in Pmw.Blt.Graph()

[Ike H. <ha...@nh...>]

Hi all,

A few weeks ago I posted asking if anyone else saw the memory leak I saw in
Pmw.Blt.Graph().   After doing a bit more playing with sample code, and some
method hunting, I found that the memory leak actually exists in
Pmw.Blt.Vector and is a known bug in BLT.  (apparently patches are comming)
But, there is a way aound this.

Generally, according to sample code on the Pmw website, Vectors are to be
treated *almost* the same as lists (at least that is my impression) so that
if you have a line with a vector (or 2 vectors) defining the points on the
line, one can just modify the values, or append values on the end or remove
them or whatever, the same as on would for a python list.  However, doing
any of these is the cause of the memory leak.  There is an alternative,
which is a bit more CPU intensive, but if one is graphing lots of data (as I
was when I discovered this) the memory problem goes away.  the trick is to
list-ify the vector by using the command list(vector) and making
modifications to the data in the list object you create, then using
Pmw.Blt.Vector.set(list) to 'set' the vector to the data in the list.

Example:

Old way:

vector=Pmw.Blt.Vector()
#creation
for i in range(10):
    vector.append(i)   #just putting incremental numbers in the
vector...doing this alot causes mem probs

#updating
for i in range(len(vector)):
    vector[i]=i+1  #this method of updating also causes problems


New way:

vector=Pmw.Blt.Vector()
#creation
a=[]
for i in range(10):
    a.append(i)
vector.set(a)

#updating
a=list(vector)
for i in range(len(a)):
    a[i]=a+1
vector.set(a)

and voilia, memory leak problem goes away.