[Patches] [ python-Patches-661719 ] allow py_compile to re-raise exceptions

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Patches item #661719, was opened at 2003-01-03 16:59
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Category: Library (Lib)
Group: Python 2.3
Status: Open
Resolution: None
Priority: 5
Submitted By: Gyro Funch (siva1311)
Assigned to: Nobody/Anonymous (nobody)
Summary: allow py_compile to re-raise exceptions

Initial Comment:
py_compile does not re-raise exceptions so that they
can be caught by the calling program. The following
example illustrates the problem:

-----begin bad_prog.py-----
print "hello
-----end   bad_prog.py-----


-----begin test_compile.py-----
from py_compile import compile

class CompileError(Exception): pass

fl = 'bad_prog.py'
try:
    compile(fl)
except Exception,msg:
    raise CompileError, '%s: %s' % (msg,fl)
-----end   test_compile.py-----

-----
[~]:python test_compile.py 
  File "bad_prog.py", line 1
    print "hello
               ^
SyntaxError: invalid token
-----
Note that CompileError is not raised.


The attached simple patch should take care of the
problem (and I hope not cause any bad side effects). 

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>Comment By: Gyro Funch (siva1311)
Date: 2003-01-06 14:48

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I have implemented a 'doraise' flag in py_compile.compile.
I think the patch should now be backwards-compatible.
However, I think that files that use py_compile in the
standard library (compileall.py and zipfile.py) should
perhaps use the new exception mechanism for clarity and as a
demonstration of how to use the exception.
What do you think?
I'm not sure if I've eliminated the 'few minor issues'. I
did  implement 'except Exception:' instead of a raw
'except:'. Is this what you meant.
Thanks for your comments.

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Comment By: Martin v. Löwis (loewis)
Date: 2003-01-06 13:27

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The patch looks fine so far, except for a few minor issues
(i.e. never to use bare except: clauses). You don't have to
implement a migration strategy: just elaborating it here
would be fine. To preserve compatibility, I could envision a
flag ('doraise' or some such), or a different entry point.
If you manage to provide full backwards compatibility, you
don't need to change any of the existing callers.

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Comment By: Gyro Funch (siva1311)
Date: 2003-01-06 13:15

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The following patch adds a 'PyCompileError' exception to
py_compile and adds the appropriate 'except' and 'raise'
clauses to py_compile.py, compileall.py, and zipfile.py (I
think that these are the only affected files in the standard
library).
The exception class messages were chosen to try to simulate
the current behavior in these files as closely as possible.

If this patch looks okay (or at least is in the right
direction), I'll begin to look at the documentation and
migration issues.


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Comment By: Gyro Funch (siva1311)
Date: 2003-01-04 15:20

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Thank you for the comments. 
I was trying to maintain some aspects of the current behavior and 
add the necessary exception raise. Clearly, this is not correct. 
I'll give this patch more thought and consider issues of 
documentation and migration as well. 

----------------------------------------------------------------------

Comment By: Martin v. Löwis (loewis)
Date: 2003-01-03 23:06

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This patch is wrong: Callers of py_compile.compile, such as
py_compile.main, now need to catch potential exceptions. As
this is an incompatible change, you need to provide
documentation, and ideally a migration strategy.

It is also unclear why you both print the exception and
raise it: If an exception is raise, it is normally the
responsibility of the caller to print the exception.

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Comment By: Gyro Funch (siva1311)
Date: 2003-01-03 21:20

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Sorry, the file should be attached now. I find the SourceForge 
web interface a little confusing.

-g

----------------------------------------------------------------------

Comment By: Gyro Funch (siva1311)
Date: 2003-01-03 21:07

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There's no uploaded file!  You have to check the
checkbox labeled "Check to Upload & Attach File"
when you upload a file.

Please try again.

(This is a SourceForge annoyance that we can do
nothing about. :-( )

----------------------------------------------------------------------

Comment By: Martin v. Löwis (loewis)
Date: 2003-01-03 20:43

Message:
Logged In: YES 
user_id=21627

There's no uploaded file!  You have to check the
checkbox labeled "Check to Upload & Attach File"
when you upload a file.

Please try again.

(This is a SourceForge annoyance that we can do
nothing about. :-( )

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