Re: ['a', 'b'][True] results 'b' But how?
kath wrote: Hi, Can any one please tell me how is the following code is working? ['a','b'] is a list of string Yes. and [True] is list of boolean value. No. It's the subscription operator applied to the list of strings. a = ['a', 'b'] a[True] may be clearer. How is it making effect? int(True) 1 int(False) 0 isinstance(True, int) True bool.__bases__ (type 'int',) code Python24 ['a','b] [True] 'b' ['a','b'] [False] 'a' ['a','b']['some_string' == r'some_string'] 'b' ['a','b']['some_string' == r'somestring'] 'a' code -- rbh -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie question: how to get started?
ed wrote: I should also mention that I know C/C++, Perl, Javascript, the basics of mySQL, and HTML/CSS. If anyone has tried to enter python from these angles, I'd be grateful to hear from you. What's C/C++? Well, I knew C, C++, Perl, Java, SQL, and HTML before learning Python. And some more languages. If you really know all these languages, Python should be a no-brainer, and a practical language in use. -- rbh -- http://mail.python.org/mailman/listinfo/python-list
Re: Re printing on same line.
Jerry Hill wrote: On 6/15/07, HMS Surprise [EMAIL PROTECTED] wrote: I want to print a count down timer on the same line. I tried print '\r', timeLeft, which just appends to the same line. Sounds to me like whatever you're printing to doesn't do what you expect when it encounters a carriage return (\r). Is your program running in a terminal? Both the windows cmd.exe shell and bash under linux seem to do the right thing when encountering a '\r'. Actually, bash has nothing to do with how the terminal handles \r. The job of the shell (bash, ksh, csh, sh ...) is to execute your script when you type its name. Outputting a \r might or might not move the cursor to the beginning of the line. It's completely system specific, and even on the same OS, it depends on the capabilities of the actual terminal the programs run on, and on some terminal emulators it might depend on configuration settings. If you need to explore the capabilities of the terminal, curses will be a good place to start. -- rbh -- http://mail.python.org/mailman/listinfo/python-list
Re: Is there any way to catch expections when call python method in C++
Allen wrote:
I use try catch, but cannot catch the execeptions of execution python
method.
PYCALL_API void PyCall(const char * pszModule, const char * pszFunc,
void * pArg)
{
if (pszModule == NULL || pszFunc == NULL)
{
return;
}
Py_Initialize();
PyObject * pModule = NULL;
PyObject * pFunc = NULL;
try {
pModule = PyImport_ImportModule(pszModule);
pFunc = PyObject_GetAttrString(pModule, pszFunc);
PyEval_CallObject(pFunc, (PyObject*)pArg);
} catch (...) {
fprintf(stderr, Error: call python method failed);
}
Py_Finalize();
}
Can I catch it from C++?
No. CPython is written in C, not C++, and C has no concept of exceptions.
Exceptions in Python is usually indicated by return value in the
interpreter, and has no mapping to the C++ exception model. You should
never let C++ exceptions propagate into the python functions either.
PyImport_ImportModule will return NULL if an exception occured, and so will
also PyObject_GetAttrString and PyEval_CallObject do.
--
rbh
--
http://mail.python.org/mailman/listinfo/python-list
Re: stdout/err and C extentions
hg wrote:
Hi,
I have the following
* C extention - redir.c
#include Python.h
PyObject * test_redir_test(PyObject *self) {
fprintf(stdout, Hello from an extention!\n);
Py_INCREF(Py_None);
return Py_None;
}
[...]
*** python test script: test.py:
import sys
class My_Stdout:
def write(self, p_string):
l_file = open('res.txt','a')
l_file.write(p_string)
l_file.close
sys.stdout = My_Stdout()
print 'toto'
import test_redir
test_redir.test()
Question:
print 'toto' does go to res.txt while Hello from an extention!\n goes
to the console.
Any clue ?
There is no portable way to change the location of stdout during execution
of a program. If you want to print with whatever is sys.stdout from an
extension module, you should call sys.stdout's write method dynamically
from C.
--
Robert Bauck Hamar
--
http://mail.python.org/mailman/listinfo/python-list
Re: stdout/err and C extentions
hg wrote:
Robert Bauck Hamar wrote:
hg wrote:
Hi,
I have the following
* C extention - redir.c
#include Python.h
PyObject * test_redir_test(PyObject *self) {
fprintf(stdout, Hello from an extention!\n);
Py_INCREF(Py_None);
return Py_None;
}
[...]
*** python test script: test.py:
import sys
class My_Stdout:
def write(self, p_string):
l_file = open('res.txt','a')
l_file.write(p_string)
l_file.close
sys.stdout = My_Stdout()
print 'toto'
import test_redir
test_redir.test()
Question:
print 'toto' does go to res.txt while Hello from an extention!\n
goes to the console.
Any clue ?
There is no portable way to change the location of stdout during
execution of a program. If you want to print with whatever is sys.stdout
from an extension module, you should call sys.stdout's write method
dynamically from C.
Robert, thanks,
I understand that sys.stdout and stdout of an extention are two different
entities ... correct ?
Yes. Python's sys.stdout and C's stdout are both objects wrapping the call
os.write(1, string) in Python and write(1, string, strlen(string)) in
C, or some other function on platforms using other mechanisms for output.
In that way sys.stdout in Python and stdout in C will be portable to many
more systems.
--
Robert Bauck Hamar
--
http://mail.python.org/mailman/listinfo/python-list
Re: newb: Join two string variables
johnny wrote: Please don't top post. Arrange your answer so that your comments follow what you comment. In my code, I have the following: p = posixpath.basename(e).strip make this: p = posixpath.basename(e).strip() filename = download_dir+p I am getting the following error: filename = download_dir+p TypeError: cannot concatenate 'str' and 'builtin_function_or_method' objects Which is correct. Because you forgot to _call_ strip, you just stored (a reference to) strip itself in p, and not its return value. (rest of message deleted, because I don't comment on it.) -- Robert Bauck Hamar Der er to regler for suksess: 1. Fortell aldri alt du vet. - Roger H. Lincoln -- http://mail.python.org/mailman/listinfo/python-list
