docs/wtfpython
docs/wtfpython
1
0
Fork 0
mirror of https://github.com/satwikkansal/wtfpython synced 2024-11-12 22:48:53 +01:00
Code Releases Activity

Fix images source in notebook

Browse Source
This commit is contained in:
Vadim Nifadev 2024-10-15 17:42:15 +03:00
parent c3e7cc9bed
commit 6702c78868
1 changed files with 3 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
irrelevant/wtf.ipynb vendored
View File

@ -355,7 +355,7 @@
" * All length 0 and length 1 strings are interned.\n",
" * Strings are interned at compile time (`'wtf'` will be interned but `''.join(['w', 't', 'f'])` will not be interned)\n",
" * Strings that are not composed of ASCII letters, digits or underscores, are not interned. This explains why `'wtf!'` was not interned due to `!`. CPython implementation of this rule can be found [here](https://github.com/python/cpython/blob/3.6/Objects/codeobject.c#L19)\n",
" ![String interning process](https://raw.githubusercontent.com/nifadyev/wtfpython/refs/heads/feature/%2374/add-dark-theme-and-alt-support-for-images/images/string-intern/string_interning.svg)\n",
"<img src=\"https://raw.githubusercontent.com/satwikkansal/wtfpython/refs/heads/master/images/string-intern/string_interning.svg\" alt=\"Shows a string interning process.\" style=\"display=block; margin:auto\">\n",
"+ When `a` and `b` are set to `\"wtf!\"` in the same line, the Python interpreter creates a new object, then references the second variable at the same time. If you do it on separate lines, it doesn't \"know\" that there's already `\"wtf!\"` as an object (because `\"wtf!\"` is not implicitly interned as per the facts mentioned above). It's a compile-time optimization. This optimization doesn't apply to 3.7.x versions of CPython (check this [issue](https://github.com/satwikkansal/wtfpython/issues/100) for more discussion).\n",
"+ A compile unit in an interactive environment like IPython consists of a single statement, whereas it consists of the entire module in case of modules. `a, b = \"wtf!\", \"wtf!\"` is single statement, whereas `a = \"wtf!\"; b = \"wtf!\"` are two statements in a single line. This explains why the identities are different in `a = \"wtf!\"; b = \"wtf!\"`, and also explain why they are same when invoked in `some_file.py`\n",
"+ The abrupt change in the output of the fourth snippet is due to a [peephole optimization](https://en.wikipedia.org/wiki/Peephole_optimization) technique known as Constant folding. This means the expression `'a'*20` is replaced by `'aaaaaaaaaaaaaaaaaaaa'` during compilation to save a few clock cycles during runtime. Constant folding only occurs for strings having a length of less than 21. (Why? Imagine the size of `.pyc` file generated as a result of the expression `'a'*10**10`). [Here's](https://github.com/python/cpython/blob/3.6/Python/peephole.c#L288) the implementation source for the same.\n",
@ -2947,11 +2947,11 @@
"\n",
"When we initialize `row` variable, this visualization explains what happens in the memory\n",
"\n",
"<img src=\"https://github.com/satwikkansal/wtfpython/blob/master/images/tic-tac-toe/after_row_initialized.svg\" alt=\"Shows a memory segment after row is initialized..\" style=\"display=block; margin:auto\">\n",
"<img src=\"https://raw.githubusercontent.com/satwikkansal/wtfpython/refs/heads/master/images/tic-tac-toe/after_row_initialized.svg\" alt=\"Shows a memory segment after row is initialized.\" style=\"display=block; margin:auto\">\n",
"\n",
"And when the `board` is initialized by multiplying the `row`, this is what happens inside the memory (each of the elements `board[0]`, `board[1]` and `board[2]` is a reference to the same list referred by `row`)\n",
"\n",
"<img src=\"https://github.com/satwikkansal/wtfpython/blob/master/images/tic-tac-toe/after_board_initialized.svg\" alt=\"Shows a memory segment after board is initialized..\" style=\"display=block; margin:auto\">\n",
"<img src=\"https://raw.githubusercontent.com/satwikkansal/wtfpython/refs/heads/master/images/tic-tac-toe/after_board_initialized.svg\" alt=\"Shows a memory segment after board is initialized.\" style=\"display=block; margin:auto\">\n",
"\n",
"We can avoid this scenario here by not using `row` variable to generate `board`. (Asked in [this](https://github.com/satwikkansal/wtfpython/issues/68) issue).\n",
"\n"