Python object overhead?

Gabriel Genellina gagsl-py2 at yahoo.com.ar
Fri Mar 23 23:21:09 CET 2007


En Fri, 23 Mar 2007 18:11:35 -0300, Matt Garman <matthew.garman at gmail.com>  
escribió:

> Example 2: read lines into objects:
> # begin readobjects.py
> import sys, time
> class FileRecord:
>     def __init__(self, line):
>         self.line = line
> records = list()
> file = open(sys.argv[1])
> while True:
>     line = file.readline()
>     if len(line) == 0: break # EOF
>     rec = FileRecord(line)
>     records.append(rec)
> file.close()
> print "data read; sleeping 20 seconds..."
> time.sleep(20) # gives time to check top
> # end readobjects.py

Your file record requires at least two objects in addition to the line  
itself: the FileRecord instance and the dictionary instance (__dict__)  
used to hold its attributes.
You can use a new style class with __slots__ to omit that dictionary:

class FileRecord(object):
     __slots__ = ['line']
     def __init__(self, line):
         self.line = line

or defer instance creation:

class FileRecords(list):
     # store here all the lines, maybe using readlines()
     def __getitem__(self, index):
         return FileRecord(list.__getitem__(self, index))

-- 
Gabriel Genellina




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