473,219 Members | 2,091 Online
Bytes | Software Development & Data Engineering Community
Post Job

Home Posts Topics Members FAQ

Join Bytes to post your question to a community of 473,219 software developers and data experts.

pep 3116 behaviour on non-blocking reads

In the RawIOBase class I read the following:

..read(n: int) -bytes

Read up to n bytes from the object and return them. Fewer than n
bytes may be returned if the operating system call returns fewer
than n bytes. If 0 bytes are returned, this indicates end of file.
If the object is in non-blocking mode and no bytes are available,
the call returns None.
I would like the developers to reconsider and return 0 bytes when no
bytes are available and let None indicate end of file.

The reason is that this can lead to clearer code that will work
independant of the blocking mode of the stream.

Consider a consumer that just has to treat each byte. Then with
the current choice the code will look something like the following
(assuming pep 315 is implemented)
| do:
| buf = stream.read(nr)
| while buf != "":
| if buf is not None:
| for b in buf:
| treat(b)
If what the method returns follows my proposal, the code to do the same
would look something like the following:
| do:
| buf = stream.read(nr)
| while buf is not None:
| for b in buff:
| treat(b)
The advantage with my propsal is that in a lot of cases an empty buffer
can be treated just the same as a non-empty one and that is reflected
in the return values of my proposal.
Antoon Pardon
Aug 9 '07 #1
1 1082
Antoon Pardon wrote:
I would like the developers to reconsider and return 0 bytes when no
bytes are available and let None indicate end of file.
That would be a major departure from the way IO has
always been handled before in Python, which follows
the Unix model.

Also, only code that deals with non-blocking streams
will ever get None, and such code is relatively rare,
so most code won't have to worry about the None case.

Even when dealing with a non-blocking stream, usually
there will be some other way (such as select) used to
determine when there is something to be read from a
stream, and it won't be read otherwise. In that case,
the code *still* won't ever see a None.

So I think the PEP has it right.

Aug 10 '07 #2

This thread has been closed and replies have been disabled. Please start a new discussion.

Similar topics

by: marbac | last post by:
Hi, i heard a lot about "undefined behaviour" in this and other newsgroups dealing with c/c++. Is there a list where all cases with undefined behaviour in C++ are listed? regards marbac
by: JKop | last post by:
Would you classify the following code as "Undefined Behaviour" or as "Non- portable"? signed main() { signed char chedder = 130; } Relevant information:
by: Mark Stijnman | last post by:
A while ago I posted a question about how to get operator behave differently for reading and writing. I basically wanted to make a vector that can be queried about whether it is modified recently...
by: DeltaOne | last post by:
#include<stdio.h> typedef struct test{ int i; int j; }test; main(){ test var; var.i=10; var.j=20;
by: grid | last post by:
Hi, A collegue of mine is of the opinion that the behaviour of the following program is defined,but I am a little apprehensive. #include<stdio.h> #include<string.h> int main() { char *c;
by: Carlo Capelli | last post by:
I found a change in the following code, that behaved correctly in VC++ 6. #include <strstream> using namespace std; void main() { char x; ostrstream(x, 100) << "pippo" << "pluto" << ends;...
by: | last post by:
I have earlier used an HttpModule that did URL rewrites on the BeginRequest event. Now I am trying to use the same module in a different application on a new and upgraded machine (winxp sp2). ...
by: temper3243 | last post by:
Hi, Many people have used this code in my project. It works because b is using the extra memory for other 4 variables.I access obj max. well here are a few questions 1) Where does it fail. I...
by: sachingoel82 | last post by:
Hi All, I find following C++ behaviour regarding temporary objects quite contradictory. Consider this: class A { ... public:
by: Sheth Raxit | last post by:
Machine 1 : bash-3.00$ uname -a SunOS <hostname5.10 Generic_118822-30 sun4u sparc SUNW,Sun-Fire-280R bash-3.00$ gcc -v Reading specs from /usr/local/lib/gcc-lib/sparc-sun-solaris2.8/2.95.3/...
by: isladogs | last post by:
The next online meeting of the Access Europe User Group will be on Wednesday 6 Dec 2023 starting at 18:00 UK time (6PM UTC) and finishing at about 19:15 (7.15PM). In this month's session, Mike...
by: isladogs | last post by:
The next Access Europe meeting will be on Wednesday 3 Jan 2024 starting at 18:00 UK time (6PM UTC) and finishing at about 19:15 (7.15PM). For other local times, please check World Time Buddy In...
by: mar23 | last post by:
Here's the situation. I have a form called frmDiceInventory with subform called subfrmDice. The subform's control source is linked to a query called qryDiceInventory. I've been trying to pick up the...
by: abbasky | last post by:
### Vandf component communication method one: data sharing ​ Vandf components can achieve data exchange through data sharing, state sharing, events, and other methods. Vandf's data exchange method...
by: isladogs | last post by:
The next Access Europe meeting will be on Wednesday 7 Feb 2024 starting at 18:00 UK time (6PM UTC) and finishing at about 19:30 (7.30PM). In this month's session, the creator of the excellent VBE...
by: fareedcanada | last post by:
Hello I am trying to split number on their count. suppose i have 121314151617 (12cnt) then number should be split like 12,13,14,15,16,17 and if 11314151617 (11cnt) then should be split like...
by: egorbl4 | last post by:
Скачал я git, хотел начать настройку, а там вылезло вот это Что это? Что мне с этим делать? ...
by: davi5007 | last post by:
Hi, Basically, I am trying to automate a field named TraceabilityNo into a web page from an access form. I've got the serial held in the variable strSearchString. How can I get this into the...
by: MeoLessi9 | last post by:
I have VirtualBox installed on Windows 11 and now I would like to install Kali on a virtual machine. However, on the official website, I see two options: "Installer images" and "Virtual machines"....

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.