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Makefile经典教程（入门必备） - C/C++ - 清泛网移动版 - 专注C/C++及内核技术
...定义的值。如：
foo = $(bar)
bar = $(ugh)
ugh = Huh?
all:
echo $(foo)
我们执行“make all”将会打出变量$(foo)的值是“Huh?”（ $(foo)的值是$(bar)，$(bar)的值是$(ugh)，$(ugh)的值是“Huh?”）可见，变量是可以使用后面的变量来...
Property getters and setters
...g to backup the computed property. Try this:
class Point {
private var _x: Int = 0 // _x -> backingX
var x: Int {
set { _x = 2 * newValue }
get { return _x / 2 }
}
}
Specifically, in the Swift REPL:
15> var pt = Point()
pt: Point = {
_x = 0
}
16> pt.x = 10...
Pretty Printing a pandas dataframe
...
I've just found a great tool for that need, it is called tabulate.
It prints tabular data and works with DataFrame.
from tabulate import tabulate
import pandas as pd
df = pd.DataFrame({'col_two' : [0.0001, 1e-005 , 1e-006, 1e-007],
'column_3' : ['ABCD', ...
Substitute multiple whitespace with single whitespace in Python [duplicate]
...ce characters that are combined.
To match unicode whitespace:
import re
_RE_COMBINE_WHITESPACE = re.compile(r"\s+")
my_str = _RE_COMBINE_WHITESPACE.sub(" ", my_str).strip()
To match ASCII whitespace only:
import re
_RE_COMBINE_WHITESPACE = re.compile(r"(?a:\s+)")
_RE_STRIP_WHITESPACE = re.co...
Unique fields that allow nulls in Django
...pty string by providing your own customized model form for Foo with a clean_bar method that turns the empty string into None:
class FooForm(forms.ModelForm):
class Meta:
model = Foo
def clean_bar(self):
return self.cleaned_data['bar'] or None
class FooAdmin(admin.ModelAdmin...
How to send a simple string between two programs using pipes?
I tried searching on the net, but there are hardly any resources. A small example would suffice.
7 Answers
...
How to write a multidimensional array to a text file?
...is specified by the comments kwarg). (This looks more verbose than it actually is...)
import numpy as np
# Generate some test data
data = np.arange(200).reshape((4,5,10))
# Write the array to disk
with open('test.txt', 'w') as outfile:
# I'm writing a header here just for the sake of readabil...
django : using select_related and get_object_or_404 together
Is there any way of using get_object_or_404 and select_related together or any other way to achieve the result of using these two together(except from putting it in try/except)??
...
MySQL “incorrect string value” error when save unicode string in Django
...8mb4 uses 33% more space than utf-8 you'll need to make these fields 33% smaller.
In this case, change the max_length from 255 to 191.
Alternatively you can edit your MySQL configuration to remove this restriction but not without some django hackery
UPDATE: I just ran into this issue again and ...
What is the difference between Normalize.css and Reset CSS?
I know what CSS Reset is, but recently I heard about this new thing called Normalize.css
9 Answers
...