qtconsole Out value prints before the print statements that precede it #780

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jdmarch opened this Issue Sep 11, 2011 · 1 comment

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@jdmarch

In [1]: def ff():
...: print '(computing)'
...: return 123

In [2]: ff()
Out[2]: 123(computing)

This does not occur in standard ipython.
Only tested on OSX.

@minrk minrk added a commit to minrk/ipython that referenced this issue Sep 12, 2011
@minrk minrk flush stdout/stderr on displayhook
This helps stream output arrive before pyout.

closes gh-780
b0f5b76
@minrk
IPython member

I see the same thing. I swear we keep fixing this, and it keeps coming back.

It's not necessarily incorrect that the 123 is coming before the printed message, because when print text actually gets drawn is controlled by sys.stdout.flush, so unless you are calling flush yourself, such things are not technically reliable (though they tend to be consistent within a given environment). What is definitely incorrect is that stdout content should never show up on the same line as pyout.

If we add sys.stdout.flush() to the zmq.displayhook prior to send, then it will behave as you are expecting, so we should probably do that (see PR #782).

@minrk minrk added a commit that closed this issue Sep 12, 2011
@minrk minrk flush stdout/stderr on displayhook
This helps stream output arrive before pyout.

closes gh-780
a677855
@minrk minrk closed this in a677855 Sep 12, 2011
@mattvonrocketstein mattvonrocketstein pushed a commit to mattvonrocketstein/ipython that referenced this issue Nov 3, 2014
@minrk minrk flush stdout/stderr on displayhook
This helps stream output arrive before pyout.

closes gh-780
6900594
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