Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>It seems to me you want to solve the wrong problem with the wrong tool. <em>If</em> all subclasses <em>define</em> (can't really say inherit) your static method, you will still be unable to call it painlessly (To call the static method on a class not known at compile time would be via reflection or byte code manipulation).</p> <p>And if the idea is to have a set of behaviors, why not just use instances that all implement the same interface? An instance with no specific state is cheap in terms of memory and construction time, and if there is no state you can always share one instance (flyweight pattern) for all callers.</p> <p>If you just need to couple metadata with classes, you can build/use any metadata facility you like, the most basic (by hand) implementation is to use a Map where the class object is the key. If that suits your problem depends on your problem, which you don't really describe in detail.</p> <p>EDIT: (Structural) Metadata would associate data with <em>classes</em> (thats only one flavor, but probably the more common one). Annotations can be used as very simple metadata facility (annotate the class with a parameter). There are countless other ways (and goals to achieve) to do it, on the complex side are frameworks that provide basically every bit of information designed into an UML model for access at runtime.</p> <p>But what you describe (processors and parameters in database) is what I christened "set of behaviors". And the argument "parameters need to be loaded once <em>per class</em>" is moot, it completely ignores the idioms that can be used to solve this without needing anything 'static'. Namely, the flyweight pattern (for having only once instance) and lazy initialization (for doing work only once). Combine with factory as needed.</p>
    singulars
    1. This table or related slice is empty.
    1. POJava - Alternatives to forcing subclass to have a static method
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USDurandal
    1. USDurandal
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COCould you describe your final paragraph in more detail. I have added more detail to the question. I want to avoid having the metadata held centrally,
      singulars
      1. PO
      1. USNick Long
    2. CO@NickLong You seem to be firmly set on the 'static' approach. You need to adjust your set of mind. Having an instance of a class opens up all the advantages of inheritance and polymorphism. Shed the thought that such a funtcion holder instance is wasted - those ~16 bytes per instance will not make your application a memory eating behemoth.
      singulars
      1. PO
      1. USDurandal
    3. COYour example of data processors + parameters *calls* for a dataprocessor *factory* that spews out initialized instances. Also mind you, *static* is *worse* than keeping anything *centrally* (the latter could at least be altered at runtime, when the need arises). Static means automatically *compile time dependency* (to avoid that you *have* to go dynamic, at least part of the way. Might as well go all the way then).
      singulars
      1. PO
      1. USDurandal
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload