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Ruby ampersand colon shortcut [duplicate]
.... The colon in this case is for the symbol. So, there's & and there's :foo.
The & calls to_proc on the object, and passes it as a block to the method. In Rails, to_proc is implemented on Symbol, so that these two calls are equivalent:
something {|i| i.foo }
something(&:foo)
Also, to_pro...
Run jar file in command prompt [duplicate]
...f you dont have an entry point defined in your manifest invoking java -jar foo.jar will not work.
Use this command if you dont have a manifest or to run a different main class than the one specified in the manifest:
java -cp foo.jar full.package.name.ClassName
See also instructions on how to cre...
Automatically creating directories with file output [duplicate]
...nction does this. Try the following:
import os
import errno
filename = "/foo/bar/baz.txt"
if not os.path.exists(os.path.dirname(filename)):
try:
os.makedirs(os.path.dirname(filename))
except OSError as exc: # Guard against race condition
if exc.errno != errno.EEXIST:
...
Get filename from file pointer [duplicate]
...
You can get the path via fp.name. Example:
>>> f = open('foo/bar.txt')
>>> f.name
'foo/bar.txt'
You might need os.path.basename if you want only the file name:
>>> import os
>>> f = open('foo/bar.txt')
>>> os.path.basename(f.name)
'bar.txt'
...
What do {curly braces} around javascript variable name mean [duplicate]
...e able to use this pattern to assign multiple variables at once:
{x, y} = foo;
Is the equivalent to:
x = foo.x;
y = foo.y;
This can also be used for arrays. For example, you could easily swap two values without using a temporary variable:
var a = 1;
var b = 3;
[a, b] = [b, a];
Browser s...
背包：将代码块复制并粘贴到不同的屏幕和项目 · App Inventor 2 中文网
...在粘贴的块中重命名为 X2。
同样，如果你尝试粘贴过程 foo 的过程定义，并且工作区已包含 foo 的定义，则粘贴的过程将被重命名为 foo2。
可以将代码块粘贴到任何项目或屏幕中吗？
是的。 但是，在某些情况下，将背包中的...
What is object slicing?
...uestions/274626#274636 for an example of how slicing occurs during method calls (which underscores the danger a little better than the plain assignment example).
– Blair Conrad
Nov 8 '08 at 13:53
...
Why does an NSInteger variable have to be cast to long when used as a format argument?
...ending on the platform, the compiler recommends
to add a cast to long generally.
Update: Since iOS 7 supports 64-bit now as well, you can get the same warning when compiling
for iOS.
share
|
improv...
When to wrap quotes around a shell variable?
... quote it if it can either be empty or contain spaces (or any whitespace really) or special characters (wildcards). Not quoting strings with spaces often leads to the shell breaking apart a single argument into many.
$? doesn't need quotes since it's a numeric value. Whether $URL needs it depends o...
Linux command to list all available commands and aliases
Is there a Linux command that will list all available commands and aliases for this terminal session?
20 Answers
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