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How to delete migration files in Rails 3
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I usually:
Perform a rake db:migrate VERSION=XXX on all environments, to the version before the one I want to delete.
Delete the migration file manually.
If there are pending migrations (i.e., the migration I removed was not the...
Remove duplicate entries using a Bash script [duplicate]
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Perl one-liner similar to @kev's awk solution:
perl -ne 'print if ! $a{$_}++' input
This variation removes trailing whitespace before comparing:
perl -lne 's/\s*$//; print if ! $a{$_}++' input
This variation edits the file in-place:
perl -i -ne 'print if ! $a{$_}++' input
This variation e...
How to create a date object from string in javascript [duplicate]
...return a JS Date object, with a robust selection of methods available from __proto__. Demo in jsFiddle
– KyleMit
Apr 11 '17 at 19:19
4
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How to do scanf for single char in C [duplicate]
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The %c conversion specifier won't automatically skip any leading whitespace, so if there's a stray newline in the input stream (from a previous entry, for example) the scanf call will consume it immediately.
One way around the problem is to put a blank space before t...
How to sort with a lambda?
...nclude <iostream>
#include <sstream>
struct Foo
{
Foo() : _i(0) {};
int _i;
friend std::ostream& operator<<(std::ostream& os, const Foo& f)
{
os << f._i;
return os;
};
};
typedef std::vector<Foo> VectorT;
std::string ...
Copy file or directories recursively in Python
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I suggest you first call shutil.copytree, and if an exception is thrown, then retry with shutil.copy.
import shutil, errno
def copyanything(src, dst):
try:
shutil.copytree(src, dst)
except OSError as exc: # python >2.5
...
ArrayBuffer to base64 encoded string
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I like the simplicity of this approach, but all that string concatenation can be costly. It looks like building an array of the characters and join()ing them at the end is significantly faster on Firefox, IE, and Safari (but quite a lot slower on Chrome): jsperf.com/to...
How to reference a .css file on a razor view?
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@Marc It's rendered on a place, where you call RenderSection (surprisingly :), not at the end of the header.
– David Ferenczy Rogožan
Mar 26 '15 at 22:13
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ORA-30926: unable to get a stable set of rows in the source tables
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This is usually caused by duplicates in the query specified in USING clause. This probably means that TABLE_A is a parent table and the same ROWID is returned several times.
You could quickly solve the problem by using a DISTINCT in yo...
Passing functions with arguments to another function in Python?
... y):
return x+y
# declare partial function
def addPartial(x):
def _wrapper(y):
return add(x, y)
return _wrapper
# run example
def main():
f = addPartial(3)
result = runOp(f, 1) # is 4
Use partial from functools
This is almost identical to lambda shown above. Then why...