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PHP Fatal error: Using $this when not in object context
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@Sarfraz No offense, but it is still wrong. You can call an instance method with ::. It is against E_STRICT, but it does work as long as the method body does not reference the instance scope, e.g. uses $this. Also, self::foo will not point to $this->foo. It references a clas...
Add column with constant value to pandas dataframe [duplicate]
...ods to gain some intuition for alignment works with objects that have partially, totally, and not-aligned-all aligned indices. For example here's how DataFrame.align() works with partially aligned indices:
In [7]: from pandas import DataFrame
In [8]: from numpy.random import randint
In [9]: df = ...
Direct casting vs 'as' operator?
... tend to almost never use 2 since if something is not the right type, I usually expect an exception to occur. I have only seen a need for this return-null type of functionality with badly designed libraries which use error codes (e.g. return null = error, instead of using exceptions).
3 is not a ca...
Align image in center and middle within div
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416
body {
margin: 0;
}
#over img {
margin-left: auto;
margin-right: auto;
disp...
What does “coalgebra” mean in the context of programming?
...coalgebras" several times in functional programming and PLT circles, especially when the discussion is about objects, comonads, lenses, and such. Googling this term gives pages that give mathematical description of these structures which is pretty much incomprehensible to me. Can anyone please expla...
bool to int conversion
...ol.h header file. true and false are also macro defined in stdbool.h.
§7.16 from C99 says,
The macro bool expands to _Bool.
[..] true which expands to the integer constant 1, false
which expands to the integer constant 0,[..]
...
Difference between case object and object
...of serialization
a prettier default implementation of toString, and
the small amount of functionality that they get from automatically inheriting from scala.Product.
Pattern matching, equals and hashCode don't matter much for singletons (unless you do something really degenerate), so you're pre...
如何查看Oracle用户的SQL执行历史记录？ - 数据库(内核) - 清泛网 - 专注C/...
...e用户的SQL执行历史记录？select * from v$sqlarea t order by t LAST_ACTIVE_TIME desc注意 ：执行此语句等等一些相关的语句 必须具有DBA 的权限 虽然
select * from v$sqlarea t order by t.LAST_ACTIVE_TIME desc
注意 ：执行此语句等等一些相关的语句 必...
How do PHP sessions work? (not “how are they used?”)
...al MARTIN
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5
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PostgreSQL create table if not exists
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CREATE TABLE myschema.mytable (i integer);
END IF;
END
$func$;
Call:
SELECT create_mytable(); -- call as many times as you want.
Notes:
The columns schemaname and tablename in pg_tables are case-sensitive. If you double-quote identifiers in the CREATE TABLE statement, you need ...