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Catching error codes in a shell pipe
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If you really don't want the second command to proceed until the first is known to be successful, then you probably need to use temporary files. The simple version of that is:
tmp=${TMPDIR:-/tmp}/mine.$$
if ./a > $tmp.1
then
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What are metaclasses in Python?
...ass is an instance of a metaclass.
While in Python you can use arbitrary callables for metaclasses (like Jerub shows), the better approach is to make it an actual class itself. type is the usual metaclass in Python. type is itself a class, and it is its own type. You won't be able to recreate somet...
Hg: How to do a rebase like git's rebase
...er mq nor rebase are enabled by default in mercurial: because mercurial is all about indelible changesets. When I work in the manner you're describing, which is nearly daily, here's the pattern I take:
1. Start working on a new feature:
$ hg clone mainline-repo newfeature-123
do a few commits (M, ...
(![]+[])[+[]]… Explain why this works
... @rlemon, there's no int data type on the language, in fact all numbers are double-precision 64-bit format (IEEE 754 values), even though some operators work internally with Integer values (like the bitwise operators) the result is always a double. The 'i' comes in this example from u...
makefile execute another target
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Actually you are right: it runs another instance of make.
A possible solution would be:
.PHONY : clearscr fresh clean all
all :
compile executable
clean :
rm -f *.o $(EXEC)
fresh : clean clearscr all
clearscr:
cle...
Print string to text file
...t_file.close()
If you use a context manager, the file is closed automatically for you
with open("Output.txt", "w") as text_file:
text_file.write("Purchase Amount: %s" % TotalAmount)
If you're using Python2.6 or higher, it's preferred to use str.format()
with open("Output.txt", "w") as text...
What does the restrict keyword mean in C++?
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A restrict-qualified pointer (or reference)...
! ...is basically a
promise to the compiler that for the
scope of the pointer, the target of the pointer will only
be accessed through that pointer (and pointers copied
from it).
In C++ compilers that support it i...
How can I get the source code of a Python function?
Suppose I have a Python function as defined below:
12 Answers
12
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List comprehension vs map
...ing map() over list comprehension or vice versa? Is either of them generally more efficient or considered generally more pythonic than the other?
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How to remove newlines from beginning and end of a string?
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String.replaceAll("[\n\r]", "");
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