docs/wtfpython
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Update explanation: Strings can be tricky sometimes

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Related to https://github.com/satwikkansal/wtfpython/issues/67
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Satwik Kansal 2018-02-25 23:30:28 +05:30
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README.md vendored
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@ -203,6 +203,8 @@ Makes sense, right?
* Strings that are not composed of ASCII letters, digits or underscores, are not interned. This explains why `'wtf!'` was not interned due to `!`. * Strings that are not composed of ASCII letters, digits or underscores, are not interned. This explains why `'wtf!'` was not interned due to `!`.
<img src="/images/string-intern/string_intern.png" alt=""> <img src="/images/string-intern/string_intern.png" alt="">
+ 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 compiler optimization and specifically applies to the interactive environment. + 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 compiler optimization and specifically applies to the interactive environment.
+ Constant folding is a technique for [peephole optimization](https://en.wikipedia.org/wiki/Peephole_optimization) in Python. This means the expression `'a'*20` is replaced by `'aaaaaaaaaaaaaaaaaaaa'` during compilation to reduce few clock cycles during runtime. But since the python bytecode generated after compilation is stored in `.pyc` files, the strings greater than length of 20 are discarded for peephole optimization (Why? Imagine the size of `.pyc` file generated as a result of the expression `'a'*10**10`)
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