6 ms·

Oh it’s even worse than overflows. The order of operations of Solidity isn’t even the same as most languages, which will undoubtedly lead to issues at some poin

Oh it’s even worse than overflows. The order of operations of Solidity isn’t even the same as most languages, which will undoubtedly lead to issues at some point. https://twitter.com/esultanik/status/976186942625861632 https://twitter.com/esultanik/status/976186942625861632

realusername 9y ago
What a bad language design... I thought they mostly copied javascript but not even that one works in javascript so who knows what they thought when designing the operators.
Buge 9y ago
I fail to see the problem in that code. (1 | 0 < 1) evaluates to False in python as well.
- b6 9y ago
  There's a, what, 50 year tradition in C of boolean ORs evaluating left to right. I don't know truthiness rules in Python, but the REPL just told me 1 is not False. So we have something that is not False ORed with True. What is your thought process?
  - bhaak 9y ago
    The issue here is operator precedence. Is it evaluated liked (1 | (0 < 1)) or like ((1 | 0) < 1). C and Javascript have the former order, Java, Ruby, and Python have the latter order.
  - Buge 9y ago
    >ORs evaluating left to right There is only a single bitwise OR here, and no logical ORs. Whether they are evaluated left to right or right to left makes no difference in the execution of this expression. Swap it left and right: (1 > 0 | 1) And you'll see that C still gives you 1, and Python still gives you False. >we have something that is not False ORed with True No. We have (in the original Python equation) 1 ORed with 0. That results in 1. Then that resultant 1 is compared ('<') with 1. That comparison results in False . The difference between Python and C is that in Python '|' has higher precedence than '<', but in C '<' has higher precedence than '|'. Dennis Ritchie admits that this is a mistake in the C language[1]. Python (and Solidity) have corrected that mistake. The reason that '|' should have higher precedence than '<' is the same reason that '+' should have higher precedence than '<'. Namely, people want to do arithmetic calculations ('|' and '+') then compare the result of those calculations ('<' and '=='). There is essentially no situation where it is useful to have '<' have higher precedence than '|'. [1] https://stackoverflow.com/questions/4685072/operator-precedence-bitwise-lower-than https://stackoverflow.com/questions/4685072/operator-precede...
    - b6 9y ago
      Thanks for the explanation. I'm not familiar with Solidity and was assuming the intent was logical or.
bhaak 9y ago
There is quite a lot to criticize Solidity but this is quite a bad example. Operator precedence is often different between languages. And because some languages miss a boolean type, you can't deduce if 1 was because of the bitwise or operator or the less-than operator. Let's take a look at (2 | 0 < 1) instead. C and JavaScript result in 3. Ruby and Python return False. Java throws a compilation error: error: bad operand types for binary operator '|'. first type: int, second type: boolean Now which of these behaviours is the one that is the universal right one? (Hint: no one, you should always know the rules of the language you program in or if you don't, just throw in some parentheses to be on the safe side)

realusername 9y ago

What a bad language design... I thought they mostly copied javascript but not even that one works in javascript so who knows what they thought when designing the operators.

Buge 9y ago

I fail to see the problem in that code. (1 | 0 < 1) evaluates to False in python as well.

b6 9y ago
There's a, what, 50 year tradition in C of boolean ORs evaluating left to right. I don't know truthiness rules in Python, but the REPL just told me 1 is not False. So we have something that is not False ORed with True. What is your thought process?
- bhaak 9y ago
  The issue here is operator precedence. Is it evaluated liked (1 | (0 < 1)) or like ((1 | 0) < 1). C and Javascript have the former order, Java, Ruby, and Python have the latter order.
- Buge 9y ago
  >ORs evaluating left to right There is only a single bitwise OR here, and no logical ORs. Whether they are evaluated left to right or right to left makes no difference in the execution of this expression. Swap it left and right: (1 > 0 | 1) And you'll see that C still gives you 1, and Python still gives you False. >we have something that is not False ORed with True No. We have (in the original Python equation) 1 ORed with 0. That results in 1. Then that resultant 1 is compared ('<') with 1. That comparison results in False . The difference between Python and C is that in Python '|' has higher precedence than '<', but in C '<' has higher precedence than '|'. Dennis Ritchie admits that this is a mistake in the C language[1]. Python (and Solidity) have corrected that mistake. The reason that '|' should have higher precedence than '<' is the same reason that '+' should have higher precedence than '<'. Namely, people want to do arithmetic calculations ('|' and '+') then compare the result of those calculations ('<' and '=='). There is essentially no situation where it is useful to have '<' have higher precedence than '|'. [1] https://stackoverflow.com/questions/4685072/operator-precedence-bitwise-lower-than https://stackoverflow.com/questions/4685072/operator-precede...
  - b6 9y ago
    Thanks for the explanation. I'm not familiar with Solidity and was assuming the intent was logical or.

bhaak 9y ago

There is quite a lot to criticize Solidity but this is quite a bad example. Operator precedence is often different between languages. And because some languages miss a boolean type, you can't deduce if 1 was because of the bitwise or operator or the less-than operator. Let's take a look at (2 | 0 < 1) instead. C and JavaScript result in 3. Ruby and Python return False. Java throws a compilation error: error: bad operand types for binary operator '|'. first type: int, second type: boolean Now which of these behaviours is the one that is the universal right one? (Hint: no one, you should always know the rules of the language you program in or if you don't, just throw in some parentheses to be on the safe side)