大约有 7,000 项符合查询结果（耗时：0.0214秒） [XML]
How to get a variable value if variable name is stored as string?
...
X=foo
Y=X
eval "Z=\$$Y"
sets Z to "foo"
Take care using eval since this may allow accidential excution of code through values in ${Y}. This may cause harm through code injection.
For example
Y="\`touch /tmp/eval-is-evil\`"...
Best way to load module/class from lib folder in Rails 3?
...So in case you try to put into lib/my_stuff/bar.rb something like:
module Foo
class Bar
end
end
It will not be loaded automagically. Then again if you rename the parent dir to foo thus hosting your module at path: lib/foo/bar.rb. It will be there for you. Another option is to name the file yo...
How to split a string in shell and get the last field
...
You can use string operators:
$ foo=1:2:3:4:5
$ echo ${foo##*:}
5
This trims everything from the front until a ':', greedily.
${foo <-- from variable foo
## <-- greedy front trim
* <-- matches anything
: <-- until the last ':'
...
Python argparse ignore unrecognised arguments
...
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--foo')
args, unknown = parser.parse_known_args(['--foo', 'BAR', 'spam'])
print(args)
# Namespace(foo='BAR')
print(unknown)
# ['spam']
share
...
Accessing dict keys like an attribute?
I find it more convenient to access dict keys as obj.foo instead of obj['foo'] , so I wrote this snippet:
27 Answers
...
Pandas: Setting no. of max rows
...hon.display import display
import numpy as np
import pandas as pd
n = 100
foo = pd.DataFrame(index=range(n))
foo['floats'] = np.random.randn(n)
with pd.option_context("display.max_rows", foo.shape[0]):
display(foo)
pandas.option_context is available since pandas 0.13.1 (pandas 0.13.1 release...
How to create a custom attribute in C#
...d, property, ...) with this attribute:
[MyCustomAttribute(SomeProperty = "foo bar")]
public class Foo
{
}
and finally you would use reflection to fetch it:
var customAttributes = (MyCustomAttribute[])typeof(Foo).GetCustomAttributes(typeof(MyCustomAttribute), true);
if (customAttributes.Length &...
Why are Python's 'private' methods not actually private?
... prevent deliberate access from outside.
For example:
>>> class Foo(object):
... def __init__(self):
... self.__baz = 42
... def foo(self):
... print self.__baz
...
>>> class Bar(Foo):
... def __init__(self):
... super(Bar, self).__init__(...
Error handling in Bash
...rror ${LINENO}' ERR
...then, whenever you create a temporary file:
temp_foo="$(mktemp -t foobar.XXXXXX)"
tempfiles+=( "$temp_foo" )
and $temp_foo will be deleted on exit, and the current line number will be printed. (set -e will likewise give you exit-on-error behavior, though it comes with ser...
How to do multiple arguments to map function where one remains the same in python?
...): \\ return '.'.join([x,y,z]) and then: list(map(f, list('abc'), repeat('foo'), list('defgh'))) returns ['a.foo.d', 'b.foo.e', 'c.foo.f'].
– Pierre D
May 13 '16 at 21:23
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