大约有 46,000 项符合查询结果（耗时：0.0867秒） [XML]
What is the proper way to check if a string is empty in Perl?
... situation where you haven't already guarded against undef, then the catch-all for "non-empty" that won't warn is if (defined $str and length $str).
share
|
improve this answer
|
...
What is javax.inject.Named annotation supposed to be used for?
...
So @Named really is @Qualifier, so why is @Qualifier required to be so generic, is the idea to allow someone using javax.inject to define stereotypes like @Repository,@Service,@Controller that are marked up as @Qualifier?
...
How to delete from select in MySQL?
...n result sets. So you need to use IN, not = in your WHERE clause.
Additionally, as shown in this answer you cannot modify the same table from a subquery within the same query. However, you can either SELECT then DELETE in separate queries, or nest another subquery and alias the inner subquery resul...
How to correctly close a feature branch in Mercurial?
...heads anymore. The only thing that could possibly annoy you is that technically the revision graph will still have one more revision without childen.
Update 2: Since Mercurial 1.8 bookmarks have become a core feature of Mercurial. Bookmarks are more convenient for branching than named branches. See...
How do I prevent angular-ui modal from closing?
...
Is there any way to set these dynamically -- say if the popup is in the middle of an operation that shouldn't be interrupted?
– RonLugge
Nov 28 '15 at 1:04
...
Python argparse command line flags without arguments
...a look at http://docs.python.org/dev/library/argparse.html#action (specifically store_true and store_false)
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('-w', action='store_true')
where action='store_true' implies default=False.
Conversely, you could haveaction='store_...
How can I use Bash syntax in Makefile targets?
...r GNU Make. Each target can have its own variable assignments, like this:
all: a b
a:
@echo "a is $$0"
b: SHELL:=/bin/bash # HERE: this is setting the shell for b only
b:
@echo "b is $$0"
That'll print:
a is /bin/sh
b is /bin/bash
See "Target-specific Variable Values" in the docume...
When and why would you seal a class?
... features, so that the original object cannot be "impersonated".
More generally, I recently exchanged with a person at Microsoft, who told me they tried to limit the inheritance to the places where it really made full sense, because it becomes expensive performance-wise if left untreated. The sealed...
How to undo a git merge with conflicts
...nges from before the merge, although it cannot always do so reliably. Generally you shouldn't merge with uncommitted changes anyway.
Prior to version 1.7.4:
git reset --merge
This is older syntax but does the same as the above.
Prior to version 1.6.2:
git reset --hard
which removes all uncom...
How to create a template function within a class? (C++)
... Not exactly true. The definition can be in a cpp file, as long as it is called once for each unique template parameter n-uplet from a non-template function/method after it has been defined.
– Benoît
Jun 9 '09 at 21:13
...