struct.unpack() on a stream

[Ulrich Eckhardt]

Hi!

I have a socket from which I would like to parse some data, how would I do
that? Of course, I can manually read data from the socket until unpack()
stops complaining about a lack of data, but that sounds rather inelegant.

Any better suggestions?

Uli

 

[Gabriel Genellina]

En Fri, 27 Feb 2009 09:29:16 -0200, Ulrich Eckhardt

I have a socket from which I would like to parse some data, how would I
do
that? Of course, I can manually read data from the socket until unpack()
stops complaining about a lack of data, but that sounds rather inelegant.

Any better suggestions?

Read until you get the required bytes; use the size attribute.

 

[MRAB]

En Fri, 27 Feb 2009 09:29:16 -0200, Ulrich Eckhardt


Read until you get the required bytes; use the size attribute.

The struct module has a function called "calcsize", eg:
2

That will tell you how many bytes to read.

 

[Gabriel Genellina]

The struct module has a function called "calcsize", eg:

2

That will tell you how many bytes to read.

The struct module defines also a Struct class; instead of using the module
functions, it's more efficient to create a Struct instance and call its
methods when one is going to use the same format more than once:

py> s = struct.Struct("<H")
py> s.size
2
py> s.unpack("\x40\x00")
(64,)

That's the size attribute I was talking about - too tersely perhaps.