Let's Learn Python #17 - Type Class Creation, Metaclass

This week, I cover how to create classes using the Type method and the Metaclass.

Please leave me a comment or question below! Like and Subscribe to show your support! :D

=========================================

Music by Juto: Link Coming Soon!

=========================================
--- SUPER TUTORIAL LIST!!! ---

PLAYLISTS

=========================================

[Anchor_Rainbow]

cls refers to the class we are passing in, i believe.

I'm glad to hear you are using other sources as well! Always a good practice!

[BradleyCarls]

I love these tutorials, they are helping me a lot. I do however wish that you would show some more "real world" applications for some of these things instead of just creating and printing out simple words. Other than that LOVE THESE :)

[MarkAlterBridge]

Ever since #14 I've started getting confused and disheartened in learning through these videos.

I felt like I understood clearly the reasoning behind everything you were typing up until this point - I was able to apply it to my own programs!

From lesson #15 you have started suddenly pulling these __***___ phrases out of nowhere (unless I overlooked you explaining it) and using things like 'super' and I think that's where I've gotten lost.

I no longer can see how I can apply these myself. I've continued on by just listening to #15-17 in the hopes that it all tied together and I would see the connection but I'm more confused by each ep.

Is it a case of powering through? because #24 with UI creation sounds brilliant but everything from #15-23 sounds daunting.

I'm just curious if any other absolute beginners are in the same boat as myself?

EDIT: ...and apologies that it's such a negative comment - from #1-14 you have been an incredible teacher!

[Anchor_Rainbow]

I'm glad I could help you, it's all you though! Keep up the great work! :)

[rnelert]

In 4:55 you say that those two ways of creating x are the same, but their results are actually quite different.
The first one creates x as an instance variable (x resides in the __dict__ of an instance).
The second one creates x as a class variable (x resides in the __dict__ of the class).

[WhatsRagePlaying]

These are REALLY helping me. you should get tons of more views. thank you tons :D

[omgdd]

Just wanted to point out that `MyClass` is not quite equivalent to `TypeClass` (@ 5:27). In `MyClass`, x is an instance variable (only exists in an object once the class is instantiated), while for TypeClass x is a class attribute (available on the class without instantiation).

[zowlambda]

Thank you!! This is so helpful for my programming class this semester!

[notia]

I'm a bit confused as to what Super in Singleton is calling... What is it calling exactly?
also the first arguement of super is Singleton as MyClass is of type Singleton right?

[hjyssg]

Thank you very much.  BUtI am a little bit confused here.
So the metaclass is the weird to inherit from  other class?

[ActorReneGarcia]

Hi. I'm getting the same error that a few others that are commenting here are getting:
File "C:/Python34/Python Testing/SingletonMetaClassExample.py", line 13, in <module>
    print(m.x)
AttributeError: 'MyClass' object has no attribute 'x'

Do you know why, or what I need to do differently to keep this error from happening?

[workflowinmind]

Hello great channel. Can you make a video about using it with pyqt5 ? Like i want to implement the same construct to different qt type objects :)!
Thanks

[daixtr]

i'm using linux python 2.7.5. When i used type() to create TypeClass as I followed your video, and then created 'printHam()' and stitch this function into the dictionary. I then instantiated an object of TypeClass and invoke obj.printHam(), I got the "ham" string printed.... but an additional None followed after the print... and i did not see that showing in your video.. any ideas here? thanks

[gurueng]

sir can you explain what does this mean
t.printham()
TypeError: printham() takes 0 positional arguments but 1 was given

[Makumazaan]

Is there a way to make that “x” an instance variable instead of it being an attribute of a class within type() creation method?

[kirbyurner]

Passing {"x":5} to type creates x at the class level whereas assigning self.x in __init__ populates the instance __dict__ (vs. the __class__ dict). In other words, those two ways of creating a class were not parallel. Better if the original defined x = 5 at the class level.

[Zetzitsen]

Couldn't seem to get the metaclass example working in python 3.4.3 .
" AttributeError: 'MyClass' object has no attribute 'x' "

[jubinkuriakose]

I found that defining the class
class MyClass(object): ....
as class MyClass():.... has alltogether ddifferent efffect on calling type() on the instance variable. Why is that ?

[nehalkamal]

how the cls has an attribute _instances in cls._instances??

[DKyousai]

Whoa so instead of func-ception I'm getting a class-ception feel here (love your sense of humor). So if I got this right, instead of self we have cls and cls refers to the metaclass, which the Singleton class is? (I'm printing out the further reading material!) As a sidenote, I think its awesome how the "move over self (in this case cls) one step to the parens on the left" mnemonic/trick still works here.