[Python-Dev] spurious print and faulty return values: Is this a bug...?

2001年1月20日 15:35:56 -0800

... or am I missing something?
With Python 2.0 on Windows 2000, when playing with sys.exit() and sys.argv()
I get some unexpected results.
First here is a simple case that shows what I expect. I run "caller_good.py"
which call "callee_good.py" and prints its return value. "callee_good.py"
returns 42 so "42" is printed:
 ----------------- caller_good.py --------------------
 import os
 retval = os.system("python callee_good.py")
 print "caller: the retval is", retval
 -----------------------------------------------------
 ----------------- callee_good.py --------------------
 import sys
 sys.exit(42)
 -----------------------------------------------------
 D:\trentm\tmp>python caller_good.py
 caller: the retval is 42
Now here is what I didn't expect. I changed "caller_bad.py" to pass, as an
argument, the value that "callee_bad.py" should return.
 ----------------- caller_bad.py ---------------------
 import os
 retval = os.system("python callee_bad.py 42")
 print "caller: the retval is", retval
 -----------------------------------------------------
 ----------------- callee_bad.py ---------------------
 import sys
 firstarg = sys.argv[1]
 print "callee_bad: firstarg is", firstarg
 sys.exit(firstarg)
 -----------------------------------------------------
 D:\trentm\tmp>python caller_bad.py
 callee_bad: firstarg is 42
 42 # <---- where did *this* print come from?
 caller: the retval is 1 # <---- and this retval is incorrect
Any ideas? I have not tried to track this down yet nor have I tried the
latest Python-CVS state.
Trent
-- 
Trent Mick
TrentM@ActiveState.com