Newbie: Capture output of compile_dir

[Bengt Richter]

On Mon, 15 Jul 2002 14:04:28 -0700 (PDT), Becky Hehn <chicken7373 at yahoo.com> wrote:

>In-Reply-To: <Pine.LNX.4.44L.0207152109490.1508-100000 at ods.pp.ru>
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>
>Thanks for the response.  I tried the code you gave
>me, but it didn't quite work like I wanted.  I created
>a syntax error in my python file (left out a quotation
>mark) and tried the code.  Below is the information
>from my interpreter session:
>
Idle or console window?
>
>>>> import sys
>>>> from cStringIO import StringIO
>>>> from compileall import compile_dir
>>>> path='/home/hehn/test'
>>>> orig_so = sys.stdout
>>>> sys.stdout = captured = StringIO()
At this point the interactive loop is echoing your keystrokes,
so presumably it has a a private reference to the old sys.stdout
for that purpose, but if you typed
    print 'hello'
the output would go to the StringIO() instance.

>>>> compile_dir(path,force=1)
Still echoing, but the next 3 lines probably went to sys.stderr

>File "/home/hehn/test/me.py", line 2
>Write('status)
>Syntax Error:  invalid token

>>>> sys.stdout = orig_so
Now old stdout should be active again
>>>> output = captured.getvalue()
>>>> output
>'Listing /home/hehn/test . . . Compiling
>/home/hehn/test/me.py'
>
>
>If an the prompt I just type the compile command, I
>get all the output at once(see below).  I would like
>the output variable to contain all this feedback from
>the compile_dir command.  Not just the initial two
>lines.  Any thoughts on what I did wrong?  Thank you
>in advance.
>

 Python 2.2 (#28, Dec 21 2001, 12:21:22) [MSC 32 bit (Intel)] on win32
 Type "help", "copyright", "credits" or "license" for more information.
 >>> import sys
 >>> from cStringIO import StringIO
 >>> orig_so = sys.stdout
 >>> orig_se = sys.stderr
 >>> sys.stdout = so = StringIO()
 >>> sys.stderr = se = StringIO()
 >>> print '-- firt line --'
 >>> 1/0
 >>> print '-- 2nd  line --'
 >>> print '-- 3nd  line but without eol --',
 >>> sys.stdout = orig_so
 >>> sys.stderr = orig_se
 >>> so.getvalue()
 '-- firt line --\n-- 2nd  line --\n-- 3nd  line but without eol --\n'
 >>> se.getvalue()
 'Traceback (most recent call last):\n  File "<stdin>", line 1, in ?\nZeroDivisionError: in
 teger division or modulo by zero\n'

Hm, I didn't expect a '\n' on that 3rd line. StringIO doesn't seem to define
softspace, so I wonder how you can capture an accurate copy of what would go to stdout
using print without that....

A quick experiment:
 >>> class X:
 ...     def __init__(self):
 ...         self.s = []
 ...         self.softspace=0
 ...     def write(self,x): self.s.append(x)
 ...
 >>> sox=X()
 >>> sys.stdout = sox
 >>> print 'hello',
 >>> print 'hello',
 >>> sys.stdout = orig_so
 >>> sox.s
 ['hello', '\n', 'hello', '\n']

 >>> print 'hello',;print 'hello'
 hello hello
 >>> sox=X()
 >>> sys.stdout = sox
 >>> print 'hello',;print 'hello'
 >>> print 'hello',;print 'hello'
 >>> sys.stdout = orig_so
 >>> sox.s
 ['hello', ' ', 'hello', '\n', 'hello', ' ', 'hello', '\n']

 >>> sox=X()
 >>> sys.stdout = sox
 >>> print 'hello',;sys.stdout.softspace=0;print 'hello'
 >>> print 'hello',;print 'hello'
 >>> sys.stdout = orig_so
 >>> sox.s
 ['hello', 'hello', '\n', 'hello', ' ', 'hello', '\n']

Nope, seems to be looking at original sys.stdout.softspace
irrespective of redirection. And I'm still not sure that
third line is right. Why should the interactive echo to the next
line make a difference to softspace when stdout is re-directed?
Or is that what does it? It seems like a bug someplace...

BTW, running python with the -u switch might be something to try also,
to get a better handle on the sequencing of outputs to stdout and stderr.

Regards,
Bengt Richter