HN does not use markdown code block formatting so this is hard to read. Formatting code blocks is simple, two blank spaces before any line to make it a code block and no need for extra newlines (unlike between paragraphs):
double deposit(double amount)
in (amount > 0, "Deposit amount must be positive")
out (result; result == balance)
{
balance += amount;
return balance;
}
I'm not asking about the syntax, I'm asking about the logic where a value can be equal to itself plus another value when the pre-condition is that it must be > 0.
Looks like its a typo :(
The correct way to go about this would be to return the new balance and capture the return value in the first part of the out postcondition like:
```D double deposit(double amount) in (amount > 0, "Deposit amount must be positive") out (result; result == balance) { balance += amount; return balance; } ```
My mistake!
https://dlang.org/spec/function.html#postconditions
HN does not use markdown code block formatting so this is hard to read. Formatting code blocks is simple, two blank spaces before any line to make it a code block and no need for extra newlines (unlike between paragraphs):
I've never used D, but it appears to be valid syntax. https://dlang.org/spec/function.html#postconditions
I'm not asking about the syntax, I'm asking about the logic where a value can be equal to itself plus another value when the pre-condition is that it must be > 0.
The syntax is correct but I made a logical error since balance is being compared to itself (as opposed to the new balance at the end).