Why doesn't the value of x change to 6 in the above example? I'm I "redefining" self in the value() method to no longer reflect what is self in the instance?
If you read up on the Python Data Model, you will see that numbers (actually all numerics) are implemented as an immutable (aka. not-changeable) type. This would mean that you could never (using Python numerics) implement something such that 2+2=5 (for all extremely large values of 2 )
Quote:
Originally Posted by Narnie
How does the value of x become incremented internally? What magic is happening behind the scenes?
No magic really. What is happening (even with your shorthand) is a replacement operator. The right side is evaluated, and then the left side is re-pointed to the new value (so the old value is essentially lost). You have to watch out when you use this though, because the immutable/mutable types each act differently... Read this for more info...
Quote:
Originally Posted by Narnie
Say I want to do what is verboten in Python. Make in C-like incrementor like this.
It depends on how far you are willing to go to get a "proper solution". If you want to use the "++" or "--" in-line in Python, be prepared to write the extension in C/C++ and to recompile Python just for you. You would basically be writing "object.__iplusplus__" (or something pretty close) - Again reference the Data Model to give you an idea where to look in the Python Source.
Either way you head, I applaud you for not jumping ship at the whitespace-strictness.
If you read up on the Python Data Model, you will see that numbers (actually all numerics) are implemented as an immutable (aka. not-changeable) type. This would mean that you could never (using Python numerics) implement something such that 2+2=5 (for all extremely large values of 2 )
No magic really. What is happening (even with your shorthand) is a replacement operator. The right side is evaluated, and then the left side is re-pointed to the new value (so the old value is essentially lost). You have to watch out when you use this though, because the immutable/mutable types each act differently... Read this for more info...
It depends on how far you are willing to go to get a "proper solution". If you want to use the "++" or "--" in-line in Python, be prepared to write the extension in C/C++ and to recompile Python just for you. You would basically be writing "object.__iplusplus__" (or something pretty close) - Again reference the Data Model to give you an idea where to look in the Python Source.
Either way you head, I applaud you for not jumping ship at the whitespace-strictness.
Thanks. I thought it likely had to do with the fact the int, str, etc are immutable, but lists, dictionaries are mutable. This clarifies that thinking.
As far as the last comment, HAHA!!! I'm just beginning to wrap my head around Python. No way do I want to write a C/C++ extension! BECAUSE I COULDN'T, hehe. Actually being able to right x++ or ++x to increment isn't important to me.
I have since learned about __call__ and __repr__ methods. I would nave loved to be able to make an int-like variable be assigned where I could just go x=5. Then when I needed to go x.incAfter (for x++) or x.incBefore (for ++x). I think I have realized that isn't possible.
What I have (with some help from others) figured out is:
then it works the way I envisioned:
Works ok for me and was a great teaching tool/exercise.
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Server version: Apache/2.4.12 (Unix)
Server built: May 25 2015 04:58:27
:/#:/# /usr/IBMAHS/bin/apachectl -M
Loaded Modules:
core_module (static)
so_module (static)
http_module (static)
mpm_worker_module (static)
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"/home/xyz/public_html/index.php"
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abc
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3G_CENTRAL;INDONESIA_(M)_TELKOMSEL;SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL
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Im not able to understand, what exactly it is doing :confused:
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Lokesha (4 Replies)