Smalltalk superclass vs metaclass? -

-

I'm new to OOP, but with a "procedural" background.

I am currently trying to take my head around the OOP through the "Smalltalk: Receiving Message" GO Smalltak and Lovejoy.

I am confused as Met's Metals and Metacas class, I can see the legacy flow of Superclass I Superclass -> Class -> Subclass; But I do not know how / where fits in metaclass. TIA ...

Description in an excellent free online book, Chapter 13 (Classes and Metcalaces). Things mentioned in this chapter are common for all small-scale applications.


Comments

Post a Comment

Popular posts from this blog

objective c - iPhone and it's wireless area -

-
Is this a way to find other iPhones in the category of wireless areas? So I give an example. I'm staying at the airport somewhere I have an iPhone too. I and the other iPhone owners are playing the same game. Is there any way to warn me and the other player that we are close to each other? Does this work even if we are not on the same wireless network, or there is no wireless? And if there is any way to do this, can you give me some starting point? Like a link where I can learn something like this or maybe this is probably the name of this process, because I do not know how to search about this topic in Google. Thanks in advance! Can be completed with peer-to-peer discovery and connectivity you are describing Game Kit Framework Originally I thought it works only through Bluetooth, but after watching it immediately, it seems that WiFi is also supported. Hope it helps!
Read more

unix - Listing all shared memory segments used by a process on AIX5.3+ -

-
I would like to find all the shared memory segments used by a given process I am particularly interested in detecting shmid That's why I can use it in call (shmctl). On Solaris I will just read / proc / $ PID / map to find that information (field pr_shmid) The content of that file is defined by struct prmap_t in the sys / procfs format. Ax also has a / proc / $ PID / map file. Any project is a primate, but unfortunately it has been projected in pr_shmid field. Any ideas how can I get it on AIX5.3 +? I do not particularly know about AX, but I think that ipcs command is quite standard where SysV IPC is supported, so I want to get the ipcs -m command to give the appropriate code; If you can not find a better method, then there may be an option to parse its output.
Read more

tsql - Correct sql/hql query (aggregate in where clause) -

-
I want to query the query as below but the question is wrong but describes my intentions. select name, date time, data from record, date time = maximum (date time) Update: OK The description of the query intentions is not very good. My bad I want to select the latest record for each person. i like Mickey's answer and quosnoye (and upyoyed miki), but if your needs are similar to me , You should keep in mind some limitations. First and foremost, this works only when you are looking for the latest record or latest record for the same name. If you want the latest record for each person in a set (a record for each person but the latest record for each), then the above solutions are small. Second, and less importantly, if you work with a large dataset, then it can be slow for a long time. So, what's around the work? Whatever I do is to add a small field to mark the "latest" in the table. Then, when I store a record (which is done in the stored procedu...
Read more